This book was suppo ed by p ojec LTI20004 "En i onmen al Resea ch and
De elopmen In o ma ion Cen e" unded by Minis y o Educa ion, You h and
Spo s o he Czech Republic, p og am INTER-EXCELLENCE, subp og am
INTER-INFORM.
III
Con en s
Abs ac .................................................................................................................... VII
1 In oduc ion o he P oblem ............................................................................... 1
1.1 His o y ......................................................................................................... 3
1.1.1 His o ical De elopmen o Wooden B idges ....................................... 3
1.1.2 B idges in An iqui y ............................................................................. 3
1.1.3 B idges in he Middle Ages .................................................................. 5
1.1.4 B idges in Renaissance ........................................................................ 5
1.1.5 Wooden B idges in Medie al China .................................................... 7
1.1.6 Swiss B idge School ............................................................................. 8
1.1.7 Wooden B idges in Ame ica ................................................................ 9
1.1.8 Wooden B idges a he Beginning o he Railway ............................... 9
1.2 Ma e ial .....................................................................................................12
1.2.1 Wood Cons uc ion ...........................................................................12
1.2.2 Submic oscopic Wood Cons uc ion .................................................12
1.2.3 Mic oscopic Wood Cons uc ion .......................................................13
1.2.4 Mac oscopic Wood Cons uc ion ......................................................16
1.2.5 Wood P ope ies ...............................................................................19
1.3 Wood in Numbe s .....................................................................................26
2 Resea ch Ques ion and Aims o he Wo k ........................................................29
3 Hypo hesis .........................................................................................................31
4 Me hodology and Me hod o O ganizing he Collec ion and Acquisi ion o
Expe imen al Da a .....................................................................................................33
4.1 Empi ical Me hods ....................................................................................34
4.1.1 Obse a ion Me hods ........................................................................34
4.1.2 Measu emen Me hods.....................................................................35
4.1.3 Expe imen al Me hods ......................................................................36
4.2 Theo e ical Me hods .................................................................................37
4.2.1 Theo e ical Me hods Based on he Logic o Thinking .......................37
4.2.2 Theo e ical Me hods Based on Analogy and Modeling ....................37

IV Con ens
5 Analysis o Selec ed B idge S uc u es in he Czech Republic...........................39
5.1 De ailed Analysis .......................................................................................40
5.1.1 ...................................................................................40
5.1.2 .................................................................................................47
5.1.3 ................................................................................................54
5.2 Analysis o Humidi y Condi ions ................................................................61
5.2.1 Leno a ................................................................................................63
5.2.2 ...........................................................................................64
5.2.3 Mod a a ............................................................................................65
5.2.4 Polka ..................................................................................................66
5.2.5 .......................................................................................67
5.2.6 no ice .......................................................................................69
5.2.7 ...............................................................................70
5.2.8 ................................................................................................71
5.2.9 bo .................................................................................................72
5.2.10 .......................................................................................73
5.2.11 ................................................................................74
5.2.12 ..........................................................................................75
5.2.13 ..........................................................................................76
5.2.14 -B no ....................................................................................76
5.2.15 ...............................................................................................78
5.2.16 ..........................................................................................78
5.2.17 ................................................................................................80
6 Possible Solu ions o Sho Li e .........................................................................81
6.1 Timbe -conc e e B idge Cons uc ions .....................................................83
6.1.1 Labo a o y Measu emen s ................................................................85
6.2 Composi e Ma e ials .................................................................................94
6.2.1 Labo a o y Measu emen s ................................................................95
6.2.2 IN-SITU .............................................................................................100
7 Discussion, conclusion .....................................................................................105
Con ens V
7.1 The Quali y o he Wood Used ................................................................107
7.2 En i onmen al Impac .............................................................................108
7.3 Design Solu ion ........................................................................................113
7.4 Closing Wo d ...........................................................................................114
8 Li e a u e .........................................................................................................115
VII
Abs ac
The i s pa o he monog aph con ains basic in o ma ion abou he his o ical
de elopmen o b idge cons uc ion no only om he en i onmen o Cen al
Eu ope. In he i s block, he basic ac s abou he ma e ial, i s p ope ies and
s uc u e a e also gi en.
The main pa o he monog aph includes he o iginal esul s o esea ch on eal
s uc u es and labo a o y samples in o de o con i m o e u e he hypo hesis o
his wo k. The esea ch esul s con ain se s o e alua ed da a mainly om b idge
cons uc ions om Cen al Eu ope. Regional a ge ing is delibe a e wi h ega d o
clima e and wood-des oying ac o s.
The monog aph b ings new app oaches o he solu ion o mode n wood-based
b idge s uc u es. I is mainly he design, de elopmen and es ing o wood-conc e e
load-bea ing sys em o b idges and insula ion sys em o b idge cons uc ion.
This wo k is based on his o ical s uc u al and ma e ial ac s abou wooden b idges
and oo b idges and on he ailu es o exis ing s uc u es, in o de o b ing a new
mode n solu ion o he de elopmen o he ield o wood-based b idge cons uc ion
no only o Cen al Eu ope.
6 Chap e 1
2022
a) b)
Fig. 1.6 b idge designs a) A. Palladio, b) Faus o Ve an io. [11]
I is clea om ig. 1.6 ha he Renaissance builde s had al eady hough h ough he
b idge cons uc ion sys ems ha a e s ill in use oday, bu hey did no ye ha e ou
cu en ma e ials and echnologies a ailable. The Palladian wooden co e ed b idge
om 1567 Pon e deli Alpini nea Bassano has been p ese ed o his day, ig. 1.7.
Acco ding o Leona do da Vinci's d awings, models o wooden b idges we e made,
ig. 1.8." [11]
Fig. 1.7 Pon e deli Alpini in Bassano (A. Palladio - 1567). [11]

In oduc ion o he P oblem 7
Analysis o Selec ed Li e Fac o s o Wooden B idges
Fig. 1.8 Leona do da Vinci b idge design models (a ound 1500). [11]
1.1.5 Wooden B idges in Medie al China
"A he end o he las cen u y, w i en eco ds and he emains o unique wooden
b idges we e disco e ed in China. These so-called "Rainbow B idges" only exis ed in
China 900 yea s ago [3]. These we e a ch b idges, in which he a ch was c ea ed in a
special way o " angled" s aigh logs, ig. 3.9. The b idges we e unco e ed, and
abou a hund ed o hem we e buil . In 1999, Ame ican and Chinese expe s, using
medie al echniques, managed o es o e he "Rainbow B idge" in Jinzh, ig. 1.9.
The e was also a co e ed a ian o hese b idges (Lounge B idge), o which
app oxima ely 400 we e buil . These b idges we e buil up o a span o 30 m. Figu e
1.10 shows an example o such a b idge. The Xidong B idge was buil in 1746, wi h a
leng h o 41.7 m, a wid h o 4.9 m, and a span o 25.7 m." [11]
a) b)
Fig. 1.9 a) diag am o he wooden suppo ing s uc u e, b) he econs uc ed
"Rainbow B idge" in Jinzh. [11]
8 Chap e 1
2022
Fig. 1.10 Xidong B idge in China om 1746. [11]
1.1.6 Swiss B idge School
"The cons uc ion o wooden b idges has a long and ich adi ion in Swi ze land. The
mos amous is p obably he co e ed wooden b idge o e he Rhine nea
Scha hausen ( ig. 1.11) buil by he ca pen e Hans Ul ich G ubenmann (1709-1783).
Wi h a span o 119 m wi h in e nal suppo , he b idge was buil in 1758 and was
des oyed by Napoleon's oops on Ap il 13, 1799. The builde wan ed o build he
b idge wi hou cen al suppo , bu he ci y councilo s we e o ced o inse he
pilla . A e comple ing he b idge, he emo ed he middle suppo and hus p o ed
his mas e y. B o he s Hans and Jean G ubenmann buil o he co e ed b idges, such
as he b idge a We ingen (1778) wi h a span o 110 m ( his b idge was also
des oyed in 1799) and he co e ed b idge a Reichenau ( ig. 1.12)." [11]
Fig. 1.11 B idge o e he Rhine a Scha hausen (1758-1799). [11]
Fig. 1.12 B idge o e he Rhine nea Reichenau. [11]
In oduc ion o he P oblem 9
Analysis o Selec ed Li e Fac o s o Wooden B idges
1.1.7 Wooden B idges in Ame ica
"Hund eds o wooden oad b idges, bu especially ail oad b idges, we e buil in
Ame ica du ing he 19 h cen u y. Ve y well known is he so-called "Colossus" ( ig.
1.13) - a wooden b idge o e he i e Schuykill wi h a la la ice a ch wi h a span o
104 m, wi h a c oss-sec ion consis ing o six beams wi h a c oss-sec ion o 150x300
mm. The b idge was buil in 1812 by Lewis We nwag, who emig a ed o he USA
om Reu lingen, Ge many. To da e, he e a e nea ly 500,000 b idges in he Uni ed
S a es, mos ly o smalle spans, o which 7% a e wooden and ano he mo e han 7%
ha e a leas a wooden b idge deck." [11]
Fig. 1.13 B idge in he USA om 1812. [11]
1.1.8 Wooden B idges a he Beginning o he Railway
"In he 19 h cen u y, he e was a apid de elopmen o ailways in Eu ope and on
he Ame ican con inen . This equi ed many b idges, which we e buil o s one, b ick,
bu in he beginning also o wood. S eel began o ex ude o he ma e ials a ailway
b idges a he end o he 19 h cen u y in connec ion wi h he de elopmen o i s
indus ial p oduc ion when i was signi ican ly imp o ed and educed in p ice.
An example o a success ul wooden s uc u e o a ailway iaduc can be he Po age
B idge ( ig. 1.14), which se ed ail anspo in he USA om 1852 o 1875. A la ice
gi de b idge 170 m long and 71 m high was suppo ed by a sys em o i e-s o ey
wooden suppo s based on s one pilla s." [11]
10 Chap e 1
2022
Fig. 1.14 Po age B idge ail oad iaduc in he USA. [11]
"The in o ma ion gi en in he p e ious chap e s is jus a e y b ie and incomple e lis
o he ich his o y and adi ions o wooden b idges, which da es back o he
beginnings o human his o y. A e he decline in he cons uc ion o wooden b idges
in he i s hal o he 20 h cen u y, caused by he ad en o mode n s eel and
conc e e s uc u es, a enaissance o wooden b idge s uc u es has been aking place
since he 1960s, especially in he a ea o oad b idges and oo b idges. This
de elopmen was made possible by de eloping new wood-based cons uc ion
ma e ials, new ypes o join s, and design p ocedu es, including mode n compu e
echnology and p oduc ion echnologies. Con empo a y wooden b idges and
oo b idges a e discussed in he ollowing chap e ." [11]
The e a e abou 20 his o ic co e ed b idge s uc u es in he Czech Republic. Many
o hese buildings ha e no been p ese ed, as hey we e eplaced by mo e mode n
s uc u es o des oyed by bombing du ing Wo ld Wa II and loods, such as wo
i e . P obably he oldes p ese ed b idge s uc u e
was buil in 1719. The suppo ing cons uc ion o he b idge
made o i wood is s ill o iginal.
I is a wo-pole beam b idge, he suppo ing elemen s o which a e la ge-diame e
ough-hewn beams. Fo his b idge in he 3 d cen u y, i was necessa y o epai
mainly he cladding o p o ec he suppo ing s uc u e om he wea he .
In oduc ion o he P oblem 11
Analysis o Selec ed Li e Fac o s o Wooden B idges
Fig. 1.15 H
buil -in 1721, he Rechle in Leno a om 1870, o he imbe ed co e ed b idge in
egion.
All o hese b idges ha e su i ed o cen u ies, and hei longe i y can inspi e
mode n wooden b idge cons uc ions. [11], [3]

12 Chap e 1
2022
1.2 Ma e ial
1.2.1 Wood Cons uc ion
"The ana omical s uc u e o wood la gely de e mines i s echnical p ope ies, and
i s knowledge is he e o e essen ial in moni o ing he beha iou o wooden elemen s.
This issue can be ound in mo e de ail, o example, in he publica ions: [1] o [8]. The
wood s uc u e can be obse ed and desc ibed om he pe spec i e o mac oscopic,
mic oscopic and submic oscopic poin o iew." [11]
1.2.2 Submic oscopic Wood Cons uc ion
"Submic oscopic s uc u e deals wi h he chemical composi ion o wood and
molecula s uc u e. The chemical composi ion o wood is p ac ically he same o all
ees species: 49.5% ca bon, 44.2% oxygen, 6.1% hyd ogen, and 0.2% ni ogen.
Chemical elemen s hen o m se e al complex o ganic compounds:
cellulose (40-50% o weigh );
hemicellulose (20-30% o weigh );
lignin (25-30% o weigh );
ex ac s (0-10% o weigh ).
Cellulose (C6H10O5) n is a polysaccha ide whose chain mac omolecules consis o
glucose uni s ha a e linked by 1-4 -glycosidic bonds. The cellulose mac omolecule
is linea , homogeneous (elemen a y ib il, mic o ib il). F ee spaces be ween
mic o ib ils (so-called in e micella spaces) can hold small molecules (e.g., wa e ),
which causes he wood o swell. The a e age deg ee o polyme iza ion o cellulose
o a e age wood is gi en o 1000 o mo e. Cellulose is a ela i ely less eac i e
componen o wood. Cellulose has high ensile s eng h, compa able o o dina y
s eel. The modulus o elas ici y along he cellulose chains eaches up o 130 GPa; he
modulus o elas ici y pe pendicula o he ibe axis is app oxima ely 30 GPa.
Hemicellulose is also a polysaccha ide wi h a sho e chain o he e ogeneous linea
mac omolecules. The a e age deg ee o polyme iza ion o hemicellulose is 150-250.
They a e mo e o en ep esen ed in deciduous wood han coni e s. They a e di ided
in o hexosans (C6H10O5) n, which occu mainly in coni e s, and pen osans (C5H8O5)
n, which p edomina e in deciduous ees. Hemicellulose o ms he link be ween
cellulose and lignin. Hemicellulose and cellulose o m a polysaccha ide componen o
he wood mass, which is collec i ely called holocellulose.
Lignin is a mac omolecula subs ance o a oma ic iso opic na u e wi h a modulus o
elas ici y o only a ound 2000 MPa. I s mac omolecules a e la ge, h ee-dimensional,
and highly eac i e. Lignin is he cause o he elas ic-plas ic p ope ies o wood.
In oduc ion o he P oblem 13
Analysis o Selec ed Li e Fac o s o Wooden B idges
Hemicellulose and lignin signi ican ly a ec he comp essi e s eng h o wood ibe s.
Reducing he con en o hemicellulose and lignin in he wood leads o a educ ion in
he s eng h o he wood.
Ex ac subs ances, which a e accompanying subs ances ha can be sepa a ed by
ex ac ion, a e no di ec ly pa s o he wood s uc u e. Common ex ac subs ances
a e ola ile acids, essen ial oils, alcohols, dyes, mine al compounds, e c. Howe e ,
hey signi ican ly a ec he physical p ope ies o he wood. They inc ease he densi y
o he wood and educe he le el o equilib ium mois u e o he wood. The con en o
ola ile ex ac s inc eases he du abili y o wood. The mos c ucial ex ac an is
esin." [11]
1.2.3 Mic oscopic Wood Cons uc ion
s a e common o many di e en ee species. The
cell wall skele on is o med by cellulose, which is joined in o la ge s uc u al uni s,
so-called elemen a y ib ils. These a e g ouped in o so-called ib ous mic o ib ils.
Each mic o ib il con ains app oxima ely 100 o 2000 cellulose chains, as well as
hemicellulose and lignin. Figu e. 1.16 shows he s uc u e o he cell wall o he wood
ibe schema ically. The e is a laye o he so-called middle lamella (ML) be ween he
indi idual cells, which connec s he cells o he issue. I consis s p edominan ly o
lignin and pec in and con ains almos no cellulose. The cellulose mic o ib ils o m an
i egula la ice in he p ima y wall (P). The hickness o his p ima y wall is
app oxima ely 5% o he o al cell wall hickness. The seconda y wall in no mal wood
I consis s o lamellae o mic o ib ils o med by cellulose chains. The lamellae a e
helically de lec ed o he le and clockwise om he longi udinal axis o he cell by
abou 50 o 700. The hickness o laye S1 is app oxima e wice he hickness o he
p ima y wall. A subs an ial pa o he seconda y wall (85% o he hickness) consis s
o a laye S2 wi
clockwise lamellae wi h minimal de ia ion om he longi udinal axis o he ibe (10-
300). The inne laye S3 is simila o laye S1. The mic o ib ils o his laye a e also
helically de lec ed in he opposi e di ec ion by 60 o 900.
14 Chap e 1
2022
Fig. 1.16 Schema ic s uc u e o he cell wall. [11]
When obse ing wood unde a mic oscope (a a magni ica ion o a leas 20 imes),
i can be e i ied ha he wood consis s o cells o a ious shapes and sizes, wi h
o he speci ic ea u es in isible o he naked eye. The basic cell ypes a e ascula
cells, acheids, lib i o m ibe s, and pa enchymal cells. Depending on hei size and
s o age me hod, hei unc ion is di e en in li ing wood and s ill o ming and in
inanima e wood, which is al eady dead. Howe e , i should be bo ne in mind ha he
indi idual cell ypes do no occu in isola ion. They o m mo e o less homogeneous
g oups issues cha ac e ized by he same o ien a ion and speci ic a angemen o
cells. Figu e 1.17 shows he basic cell ypes.
The ascula cells a e ela i ely b oad, cylind ical cells. They a e pe o a ed a he
ends o allow con ac wi h adjacen ascula cells. Con ac wi h he cells su ounding
he ascula cells on hei longi udinal sides is p o ided by hinning o he cell walls -
do s and colons. In some ypes o wood, he e is a helical ein o cemen on he inne
su ace; in o he species, he e a e memb anes in he ascula cells ( ulles) closing
he cell ca i y o he ascula cell. Vascula cells occu only in deciduous ees.
The basic building block o coni e s is 95% o he s em olume o long homogeneous
cells - acheids. Howe e , hey also occu in deciduous ees. These a e elonga ed
cells - ubes o squa e c oss-sec ion wi h ounded co ne s 2 o 5 mm long and 10 o
a e o ien ed pa allel o he longi udinal axis o he unk. Du ing he ansi ion om
sp ing wood o he summe wall, he cells hicken; while he diame e o he cells
dec eases, he leng h o he cells inc eases. This c ea es a di e en densi y o sp ing
In oduc ion o he P oblem 15
Analysis o Selec ed Li e Fac o s o Wooden B idges
and summe wood in a a io o app oxima ely 1: 3. Howe e , adially o ien ed
acheids (so-called acheid ays) also occu in he wood s uc u e, in e up ing
longi udinal acheids a ce ain in e als and ensu ing adial dis ibu ion o
nu ien s. T acheid beams a e sho e han longi udinal acheids, measu ing only
abou 0.1 o 0.2 mm in leng h. T acheids a e adap ed o conduc wa e and nu ien s.
The exchange o subs ances ( hus also mois u e) be ween he cells occu s by hinning
in he cell walls - do s. In coni e ous wood, he p edominan ype is he colon. Tulles
a e no o med in acheids; helical ein o cemen s on he inne su ace o he walls
ha e only hose ypes o wood ha con ain hem in he ascula cells.
Fig. 1.17 basic ypes o wood cells: a) wide ascula link wi h pe o a ions, b)
na ow ascula link wi h pe o a ions and helical ein o cemen , c) na ow ascula
link wi h ladde pe o a ions, d) acheid, e) acheid wi h helical ein o cemen , )
wood pa enchymal cells, g), h) ay pa enchymal cells - ho izon al and up igh , i)
lib i o m ibe , j) ib ous acheid, k) la ice pe o a ion o he ascula cell. [11]
Lib i o m ibe s a e long and hin, mos ly ela i ely hick-walled, spindle-shaped cells.
Simple ine hinning - sli colons - a e isible on hei walls. The leng h o hese cells
is a iable wi hin he annual ing; he sho es a e in sp ingwood, he longes a e in
summe wood. They occu only in deciduous ees.
Pa enchymal cells ha e a di e en cha ac e om all p e iously desc ibed cell ypes.
They a e cubic, e en elonga ed o e en i egula , p isma ic in shape, ela i ely hin-
walled wi h a wide cell ca i y. The walls con ain a la ge numbe o simple hinning -
do s. They a e adap ed o conduc and s o e nu ien s. Thei leng h is abou 0.1-0.2
mm, and hei hickness is abou 0.01-0.05 mm.
In addi ion o basic cell ypes, ansien cell ypes (e.g., ib ous acheids, ib ous
pa enchymal cells, e c.) also occu in some deciduous woods.
22 Chap e 1
2022
wood species
mois u e de o ma ion coe icien
pe pendicula o he ibe s
pa allel o he ibe s
angen ially
adially
coni e s
0,32
0,16
0,01
deciduous ees
0,40
0,20
0,01
plywood
0,30
chipboa d
0,45
-
0,70
Tab. 1.1 A e age alues o he mois u e de o ma ion coe icien when he mois u e
con en o wood changes by 1%. [11]
Fig. 1.22 De o ma ion o c oss-sec ions cu om di e en log pa s a e d ying. [11]
The mos impo an p ope ies also include he mal conduc i i y and longi udinal
he mal expansion. The wood i sel has low he mal conduc i i y. The he mal
conduc i i y o wood is low due o i s low bulk densi y and po osi y. Howe e , i is
di e en in he di ec ion o he ibe s and pe pendicula o he ibe s (i is
app oxima ely hal ) he he mal conduc i i y o wood inc eases wi h inc easing
bulk densi y and inc easing humidi y.
The mal elonga ion is lowe han o me als and conc e e. Fo sp uce wood, i is 6x10-
6 K-1 along he ibe s and 34x10-6 K-1 pe pendicula o he ibe s; o oak wood, i is
4x10-6 K-1 along he ibe s and 28x10-6 K-1 pe pendicula o he ibe s.
D y wood is a e y good insula o . The speci ic elec ical esis ance o wood is
smalles in he di ec ion pa allel o he ibe s. I is app oxima ely doubled
pe pendicula o he ibe s. The elec ical esis ance o wood is in e sely p opo ional
o empe a u e and humidi y. The elec ical esis ance o wood is he mos sensi i e
o changes in humidi y. This ac is used in elec ical esis ance hyg ome e s.

In oduc ion o he P oblem 23
Analysis o Selec ed Li e Fac o s o Wooden B idges
The c i ical pa ame e s o he design o s uc u es a e mainly he mechanical
p ope ies o wood (especially lexibili y, s eng h) exp ess i s abili y o wi hs and
ex e nal loads. I is necessa y o dis inguish be ween he p ope ies o pe ec wood
(i.e., basically wood mass) and s uc u al wood. The p ope ies o pe ec wood show
conside able dispe sion, which is exace ba ed by g ow h i egula i ies, dimensions,
humidi y, empe a u e, na u e o he load (s a ic, dynamic, impac ), du a ion o load
e ec s, nega i e en i onmen al in luences. The wood p ope ies show a conside able
a iance be ween indi idual ees o he same species o wood bu also wi hin he
c oss-sec ion o he unk, bo h in c oss-sec ion and along he leng h o he unk. The
wood shows e y di e en p ope ies wi h a signi ican a iance e en wi hin he
annual ing he di e ences a e be ween sp ing and summe wood.
Due o i s aniso opy, wood shows di e en mechanical p ope ies in he di ec ion o
he ee main axis (longi udinal - pa allel o he ibe s, pe pendicula o he ibe s - in
he adial and angen ial di ec ion o he annual ings - see ig. 1.23). No mal and
angen ial s esses in he di ec ions o he main axes a e shown in ig. 1.23. Fo wood,
he s eng hs a e de e mined in:
bending ( m);
ension pa allel o he ibe s ( , 0) and pe pendicula o he ibe s ( , 90);
p essu e pa allel o he ibe s ( c, 0) and pe pendicula o he ibe s ( c, 90);
shea ( ) and o sion ( o ).
Fo wood, h ee di e en moduli o elas ici y E (EL, ER, ET), h ee moduli o elas ici y
in shea G (GLR, GLT, GRT), and six Poisson's ac o s o a e in oduced (LR, LT, RL,
RT, TL, TR). O hese 12 elas ic cons an s, 9 a e independen o each o he . Only
cons an s o di ec ions along and pe pendicula o he ibe s will su ice in he
p ac ical assessmen o he elas ici y and s eng h o wooden elemen s o s uc u al
dimensions. The di e ences in he adial and angen ial di ec ion o he annual ings
a e smalle o de s o magni ude and usually neglec ed.
When designing elemen s o wooden s uc u es, he mos impo an a e he s eng h
and de o ma ion cha ac e is ics o ma e ials.
24 Chap e 1
2022
Fig. 1.23 O ien a ion o s ess in wooden c oss-sec ion. [11]
The p ope ies o pe ec wood a e essen ially he p ope ies o he wood mass
because hei s eng h and de o ma ion cha ac e is ics a e de e mined on small
samples (e.g., o he lexu al s eng h es , he sample dimensions a e: 20/20/300
mm), which do no con ain na u al wood impe ec ions. In con as , s uc u al wood
(dimensions o eal s uc u al elemen s) has hese impe ec ions (kno s, ibe
de lec ion, c acks) a ising du ing he wood's g ow h and subsequen p ocessing o
he ex en ha hey occu in common ma e ials p oduced by manu ac u e s o wood
ma e ials. Un il ela i ely ecen ly, he ma e ial cha ac e is ics o wood we e
de e mined on small, pe ec samples, and he esul s we e hen con e ed o
s uc u al wood o eal dimensions. Eu ocodes (EC5) in oduces me hods o
de e mining he ma e ial cha ac e is ics o s uc u al elemen s.
Fig. 1.24 schema ically shows a wo king diag am o pe ec wood s essed in pa allel
wi h he ibe s - i.e., he dependence be ween ensile/comp essi e s ess and ela i e
de o ma ion. I is clea om he diag am ha he de o ma ion line o he ension
uns almos linea ly un il he b i le ailu e. Signi ican nonlinea beha io be o e
ailu e occu s a p essu e. A dashed line ma ks he ac ual cou se o he wo king
diag am; a solid line ma ks he idealized cou se o p ac ical calcula ions.
Mois u e signi ican ly a ec s he mechanical p ope ies o wood; as he mois u e
con en o he wood inc eases, he s eng h and s i ness o he wood dec ease. A e
eaching he ibe sa u a ion poin , he e is p ac ically no u he dec ease.
In oduc ion o he P oblem 25
Analysis o Selec ed Li e Fac o s o Wooden B idges
G aph 1.2 Wo king diag am o wood o ensile s ess ( ) and comp essi e s ess
( c) pa allel o he ibe s. [11]
The e ec o mois u e on he mechanical p ope ies o pe ec wood is gi en in ab.
1.2. S eng h and de o ma ion cha ac e is ics a e de e mined o wood mois u e o
12%. In p ac ice, a linea ela ionship be ween mechanical p ope ies and mois u e
con en can be conside ed o wood mois u e in he ange o 8-20%.
mechanical p ope ies change o s eng h [%]
p essu e in he di ec ion o he ibe s
6
p essu e pe pendicula o he ibe s
5
bend
4
ension in he di ec ion o he ibe s
2,5
pull
pe pendicula o he ibe s
2
shea pe pendicula o he ibe s
2,5
impac oughness
0,5
modulus o elas ici y in he di ec ion o he ibe s
1,5
Tab. 1.2 Change in he mechanical p ope ies o pe ec wood wi h a change in
humidi y o 1%. [11]
Fu he in o ma ion on he s uc u e o wood and i s p ope ies can be ound in he
li e a y sou ces [3], [5], [8], [9], [11], [17], [20], [24], [26] [36], [38], [45].
26 Chap e 1
2022
1.3 Wood in Numbe s
As a sou ce o wood be o e ag icul u e (8,000 yea s ago), o es s co e ed almos hal
o he land. Acco ding o he "Food and Ag icul u e O ganiza ion", he a ea o o es s
in 2011 was abou 31% o he land, which is abou 41 million km2. The la ges
pe cen age o he wo ld's o es s can be ound in he Russian Fede a ion, B azil,
Canada, he USA, and China.
cha ac e is ics
wo ld
EU
woodiness
[%
]
31
37,6
change in a o es a ion since 2000
-
1,2
2,8
Tab. 1.3 Fo es y and a o es a ion in he wo ld and he EU. [11]
In he Czech Republic, he o es co e unde Ma ia The esa was abou 14%, and in
2014 abou 34% and is s ill g owing. Finland leads in he EU o es y anking wi h
abou 73%. The Czech Republic is in 11 h place. The lowes a o es a ion in he
Ne he lands and I eland is abou 11%. The o al supply o wood in he Czech Republic
in 2016 was es ima ed a app oxima ely 696 million m3, and he a e age supply pe
1 ha o o es land is 265 m3. [44]
G aph 1.3 Species di e si y o o es s in he Czech Republic in 2016. [44]
The o al species composi ion o o es s in he Czech Republic in 2016 is shown in
G aph No. 1, whe e he dominan species is No way sp uce, which also o ms he
dominan mined aw ma e ial. Among deciduous ees, beech and oak ha e he
la ges ep esen a ion.
No way
sp uce pine
o he
b oadlea
es
beech oak La ch bi ch o he
coni e s
%50,5 16,4 8,5 8,3 7,2 3,8 2,3 0,3
0
10
20
30
40
50
60
In oduc ion o he P oblem 27
Analysis o Selec ed Li e Fac o s o Wooden B idges
G aph 1.4 Species change o o es wa ehouses in he Czech Republic. [9]
Sp uce monocul u es a e g adually declining due o he long- e m sus ainable heal h
o he o es . The inc ease in wood ma e ial in he Czech Republic in 2016 was
app oxima ely 17.9 million m3, and ex ac ion his yea was app oxima ely 15 million
m3. In he long un, logging does no each annual inc emen s. In 2018, mining was
inc eased due o he ba k bee le calami y. [44]
2010 2013 2014 2015 2016
coni e ous 73,9 72,9 72,5 72,3 72,1
b oadlea 25,1 25,9 26,3 26,5 26,7
0
10
20
30
40
50
60
70
80

29
2 Resea ch Ques ion and Aims o he Wo k
The main scien i ic ques ion is o de e mine he eason why cu en wooden b idge
s uc u es, despi e mode n ma e ials, echnologies, and expe ience, in many cases
do no each e en 10 yea s o li e.
quali y o he ee species used;
en i onmen al impac ;
cons uc ional solu ions.
31
3 Hypo hesis
Based on his o ical expe ience, i can be said ha wooden b idge s uc u es a e e y
du able, and hei se ice li e in he Czech Republic exceeds 300 yea s. The e a e s ill
much olde his o ic wooden b idge s uc u es ab oad, bu wood is a local aw
ma e ial wi h i s speci ics. The e o e i is necessa y o ocus on buildings made o
local ma e ials. In he EU, we can ind mode n wooden b idges olde han 25 yea s,
such
Eu opean and Scandina ian coun ies (Tynse in No way, he Reno B idge in No way,
he C es B idge in F ance and o he s).
Fig. en b idge.
The e o e, i can be assumed ha mode n b idge s uc u es, hanks o he
expe ience and mode n ma e ials such as glued lamina ed imbe , will ha e highe
du abili y han his o ical b idges ha ha e su i ed o cen u ies.

39
5 Analysis o Selec ed B idge S uc u es in he Czech
Republic
To de e mine he main causes o ailu es and insu icien se ice li e o some mode n
wooden b idge s uc u es, a de ailed analysis o exis ing b idge s uc u es in he
Czech Republic is c ucial, as wood is a local aw ma e ial wi h speci ic p ope ies o
indi idual a eas. [41] o [43]
40 Chap e 5
2022
5.1 De ailed Analysis
Based on inspec ions o abou 40 mode n wooden s uc u es in he Czech Republic,
h ee we e selec ed o de ailed analysis in o de o e eal he c i ical causes o
ailu es o hese s uc u es.
5.1.1
Wi h wooden b idges and oo b idges, including his o ic buildings, we o en come
ac oss one o he mos dange ous wood-des oying ungi om he Gloephyllum
amily. This a acks coni e ous and deciduous wood in Cen al Eu ope. De ec ing an
a ack is di icul , especially in he i s phase. A s anda d diagnos ic me hod used in
p ac ice is he so-called acous ic pe cussion me hod, which has been used since
ancien imes. Because i is a e y agg essi e and apidly sp eading species o wood-
des oying ungi, i s ea ly de ec ion is c ucial o he possibili y o emedia ion and
p e en ion o se ious ailu es o acciden s. To de e mine he occu ence o his
dange ous species o ungus, i is cu en ly possible o use many diagnos ic me hods
h ough acous ic, cul u e, and DNA es s.
c ossing he Vl a a Ri e .
Because i is a building in a p o ec ed a ea, he wood and design we e chosen as a
i h he his o ical cen e (see ig. 5.1).
Fig B idge.
I is a wo-span con inuous b idge wi h an uppe deck. The bea ings a e sliding s eel
angen ial. The e a e no b idge closu es on he b idge-building. The load-bea ing
s eel s uc u e is made o - Fal us" elemen s. The
g a ing s uc u e consis s o six main I-shaped welded beams. Rolled L-shaped
p o iles ensu e ho izon al ein o cemen . The b idge deck is made o sp uce
c ossbeams (p isms) o hickness 160 mm and a heigh o 140 mm; he b idges a e
oak wi h a hickness o . 0.05 m. The c ossba s a e o med by h ee elemen s o
Analysis o Selec ed B idge S uc u es in he Czech Republic 41
Analysis o Selec ed Li e Fac o s o Wooden B idges
di e en leng hs, as can be seen in ig. 5.2. The longes elemen s, wi h hei
can ile e , o m a suppo o he ailing cons uc ion. Medium-leng h c ossbeams
also ha e a s a ic diag am o a con inuous beam wi h o e hanging ends. The sho es
c ossbeams a e s o ed as con inuous beams. The b idges a e placed obliquely o e
he c ossba s, as can be seen in ig. 5.2.
Fig. 5.2 Scheme o dis ibu ion o wooden elemen s o c ossbeams and b idges.
The wooden s uc u e was p o ec ed wi h imp egna ing agen KORASIT CK. I is a
luid based on ch omium and coppe compounds. The compound is a wa e -soluble
sal . The imp egna ing agen ac s agains ungi and wood-des oying insec s.
Imp egna ion was applied using acuum-p essu e echnology.
Fou yea s a e commissioning, ungi o he genus Gloeophyllum appea ed on some
c ossbeams. These indings indica ed an ad anced s age in he a ack on he b idge
s uc u e.
Fig. 5.3 In es a ion by wood-des oying ungus.
42 Chap e 5
2022
The occu ence o wood-des oying ungi equi es, abo e all, sui able condi ions o
g ow h. These include he humidi y, empe a u e, and pH o he wood. In pa icula ,
he imp egna ion p e en s he wood om s icking o and being a acked by wood-
des oying ungi and hus pe ec ly p o ec s he su ace un il i s compac ness is
comp omised. C acks c ea ed only a e imp egna ion can be a way o be a acked
by wood-des oying ungi, including ungi o he genus Gloeophyllum. On he
g ew only om
c acks in he wood mass. This a ack was caused by he imp egna ion o we wood,
hanks o which he su ace o he elemen s was pe ec ly p o ec ed a he ime, bu
a e he non-d ied wood was inco po a ed in o he s uc u e, i d ied quickly in he
summe , which caused conside able d ying c acks. C acks occu ed mainly on he
sunli uppe c ossbeams side. Thanks o which wa e and di go in o he co e o he
c oss-sec ion and c ea ed ideal condi ions o a achmen and g ow h o
Gloeophyllum ungi.
Fig. 5.4 Me hod o iola ion.
In he case o an a ack o he imp egna ed elemen by Gloeophyllum ungi, which
a e ins alla ion con ains d ying c acks, he unp o ec ed co e is a acked, and he
in e nal mass o he c oss-sec ion is des oyed. Due o he imp egna ion o he
pe ime e o he elemen s, no indica ions o in es a ion by his ungus a e isible
un il he ui ing body appea s. In mos cases, he in e nal s uc u e o he wood is
i e e sibly damaged. Ea ly iden i ica ion o ungal in es a ions om he
Gloeophyllum amily is c ucial o he s uc u e's li e.
These wood-des oying ungi (Gloeophyllum spp.) A ack bo h coni e ous and
deciduous ees. They need a empe a u e ange o 5 -
60% o g ow h. This is a e y dange ous sponge, especially o building s uc u es.
The dange is mainly associa ed wi h he des uc ion o he wood mass, which
usually p og esses ou wa ds om he co e o he c oss-sec ion.
Gloeophyllum sepia ium - c ea es in he semici cula o ci cula solid ui ing bodies,
g own la e ally o in he middle. The ui ing bodies a e oughly b is ly on he
su ace, oche us ed o da k b own, and o en o m s ips. The pulp o he ui ing
Analysis o Selec ed B idge S uc u es in he Czech Republic 43
Analysis o Selec ed Li e Fac o s o Wooden B idges
body is also us y b own. I g ows on ences, ailings, and b idge s uc u es. In
houses, i is mos o en in window sills. In ec ed wood appea s o be heal hy, bu
inside i is damaged. Damage o he wood can be iden i ied by apping. The ui ing
bodies g ow om c acks and issu es. Du ing p olonged d ough , he mycelium d ies
and dies. The spo es a e cylind ical, smoo h, colo less, size 4
Gloeophyllum abie inum (Bull.: F .) P. Ka s .) has simila p ope ies. In con as o
he disc beam, which is coa sely hai y on he su ace o he ui ing bodies, he
smalle ui ing bodies o he Gloeophyllum abie inum ha e a da ke colo and a
smoo h su ace. The pulp o he o a y is ligh . The spo es a e smoo h, cylind ically
ellipsoidal, size 10- - Gloeophyllum abeum (Pe s.: F .) Mu il.) I di e s
om ungi o he genus Gloeophyllum because he d ape does no o m lea es bu
la ge po es. The ui ing bodies a e da k b own bu ini ially esemble small buns and
spill o e he subs a e, mos o en along c acks. The spo es a e cylind ical in size 7-
-
Diagnos ics
Th ee diagnos ic me hods a e mos o en used, which di e in e iciency, e idence,
and e iciency. The me hods a e chosen mainly acco ding o economic and ime
equi emen s.
acous ic pe cussion
This me hod is one o he oldes and mos o en used in cons uc ion p ac ice. This
is mainly due o he minimal demands on echnology and speed o iden i ica ion. The
me hod consis s o apping he moni o ed elemen wi h a malle and moni o ing he
hollowness o he elemen using human hea ing. Se e al ac o s can a ec his
me hod, such as he bounda y condi ions o he elemen , i s humidi y, and deg ee
o damage. Fo b idge cons uc ion, whe e he e a e a la ge numbe o he same
elemen s in e ms o bo h s o age and mois u e, his me hod can be e ec i e.
acous ic ul asonic
Acous ic me hods can also include ul asonic diagnos ic me hods ha can de ec
ca i ies in wood. These me hods canno be used on some s uc u es mainly due o
access o he moni o ed elemen s.
cul i a ion
In mic obiology, cul i a ion means he a ge ed main enance o mul iplica ion o
mic oo ganisms in i o. Bac e ia a e mos o en cul u ed on g ow h media, while
i uses a e cul u ed in cell cul u es o emb yos. Ce ain speci ic ac o s necessa y o
he g ow h o mic oo ganisms o cell cul u e main enance a e necessa y o
cul i a ion. The main ac o s a e empe a u e and ca bon dioxide ension. [10]

44 Chap e 5
2022
Fig. 5.5 Cul u e dish wi h AGAR.
I is possible o use AGAR ype cul u e medium o cul i a ion. Wood samples a e
aken om he s uc u e, C). A e
abou 5 days, i is al eady possible o de e mine whe he he s uc u e is in es ed
wi h a wood-des oying ungus. This is a labo a o y me hod.
DNA
Deoxy ibonucleic acid, commonly e e ed o as DNA, is a nucleic acid ha ca ies he
gene ic in o ma ion o all o ganisms excep some non-cellula ones. [4], [10]
This me hod enables as and accu a e bu cos ly de e mina ion o he species o
wood-des oying ungus. Fo hese pu poses, i is necessa y o ake a sui able sample
o he wood mass. This is a labo a o y me hod.
The diagnos ics aimed o de e mine he ex en o damage o he wooden c ossbeams
me hod was he acous ic pe cussion me hod, which quickly de ec ed damaged
elemen s. The second me hod was he cul i a ion me hod, which aimed o con i m
he pe cussion me hod and de e mine he exac ex en o he in es a ion. Bo h
me hods we e applied o all o e hanging c ossbeams ha we e endange ed by
unning wa e and di . On each wo-beam console, 4 sea s we e moni o ed. The i s
ield was ma ked as sec ion ABCD and sec ion KLIJ, acco ding o ig. 5.2. The second
ield was designa ed as he EFGH sec ion and he OPMN sec ion. In o al, i was a se
o 212 elemen s.
The acous ic pe cussion me hod was applied using a malle , which c ea ed an impac
on he moni o ed elemen . A p o essional echnician e alua ed he subsequen
acous ic eac ion. The acous ic sound was always compa ed wi h he esponse o he
su ounding c ossba s o mo e op imal de e mina ion o esul s. The esul was he
de e mina ion o damaged elemen s, which is indica ed in ig. 5.5.
Analysis o Selec ed B idge S uc u es in he Czech Republic 45
Analysis o Selec ed Li e Fac o s o Wooden B idges
a) acous ic me hod b) cul i a ion me hod
damaged wood in es ed wood heal hy wood
Fig. 5.6 G aphical ep esen a ion o he esul o diagnos ic me hods a) acous ic
me hod b) cul i a ion me hod [10]
The abo e g aphic ep esen a ion ig. 6.6a) shows ha abou 46% o he moni o ed
elemen s we e decla ed damaged by he acous ic pe cussion me hod. The
occu ence o he beam de e mined he p obable cause o he damage.
Cul i a ion was chosen as a con ol me hod. Samples we e aken om all moni o ed
elemen s wi h a co e d ill and sepa a ed o subsequen labo a o y e alua ion o he
occu ence o he beam.
F om he abo e g aphic ep esen a ion, ig. 6.6b) i ollows ha he cul i a ion
me hod e ealed beam in es a ion in abou 83% o he moni o ed elemen s.
Bo h me hods we e applied o he same elemen s bu wi h di e en esul s.
De e mina ion o damage o he elemen s by he acous ic hamme me hod showed
ha app oxima ely 46% o he moni o ed wooden c ossbeams a e damaged. The
emaining app oxima ely 54% showed no signs o damage. The con ol cul u e
me hod was hen con i med in abou 41% o damaged elemen s iden i ied by he
i s me hod o in es a ion wi h a wood-des oying ungus. In addi ion, i expanded
he ange o a acks on he moni o ed elemen s by abou 37%. The emaining 17%
was decla ed heal hy wood. These connec ions a e indica ed in g aph 5.1.
A B C D E F G H I J K L M N O P
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
A B C D E F G H I J K L M N O P
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
46 Chap e 5
2022
G aph 5.1 G aphical ep esen a ion o he ex en o damage and in es a ion o
wood. [15]
Damaged elemen s diagnosed by he acous ic pe cussion me hod e ealed
app oxima ely 6% o damaged s uc u al elemen s ha we e no con i med by he
con ol cul u e me hod. This di e ence can be conside ed as an e o , which could
be caused by se e al ac o s in he diagnosis, including he ex en and size o c acks,
he s uc u e o he wood, he in luence o he en i onmen , noise, and mo e. These
elemen s we e decla ed undamaged because hey did no p o e he p esence o a
wood-des oying ungus by he cul i a ion me hod. The abo e e o could also be
he e o o he cul u e me hod, whe e he mos likely cause appea s o be an
inapp op ia e sampling poin . Howe e , his ac o is e y unlikely, as sampling has
always been ca ied ou in such a way as o cap u e possible damage, bu o cou se,
i canno be uled ou .
F om he poin o iew o economic compa ison o bo h me hods, he acous ic
pe cussion me hod is mo e a o able, in a a io o 1: 5. The cul i a ion me hod's
economic complexi y consis s mainly o sampling, subsequen so ing, p epa a ion
o labo a o y diagnos ics, cul i a ion i sel , and e alua ion. The so-called DNA es
is he mos sophis ica ed and economically mos demanding me hod o de ec ing a
wood-des oying ungus.
Wood-des oying ungi om he amily o beams a e one o he bigges isks,
especially o wooden b idges and oo b idges. I s dange is mainly in he di icul y
o de ec ion by o dina y isual inspec ion. This sponge mainly a acks he co e o he
c oss-sec ion, which is no as p o ec ed by imp egna ion as he en elope o a
wooden s uc u al elemen . A e he a ack, he in e nal s uc u e o he wood mass
o he c oss-sec ional co e is e y o en des oyed, and only he imp egna ed
Analysis o Selec ed B idge S uc u es in he Czech Republic 47
Analysis o Selec ed Li e Fac o s o Wooden B idges
en elope emains undamaged. In es a ion wi h his wood-des oying ungus was
moni o ed on abou 10 s uc u es o b idges and oo b idges in he Czech Republic.
On he moni o ed s
he damage o wooden elemen s. Fo his pu pose, he acous ic apping me hod was
used, which is a common diagnos ic me hod o de e mining he damage o
elemen s due o wood-des oying ungi om he beam amily. Labo a o y cul i a ion
was chosen as he con ol me hod. The esul s show ha he classical acous ic
me hod by apping is e y accu a e in e ms o wood damage by wood-des oying
ungi om he beam amily. Howe e , as demons a ed by he cul i a ion me hod,
he ex en o he in es a ion is much la ge , mainly due o he di e en s ages o
beam g ow h in he indi idual elemen s.
The esea ch p o ed he e ec i eness and e iciency o he acous ic pe cussion
me hod. Ne e heless, i is app op ia e o ca y ou a cul i a ion me hod o ensu e
he cause o he damage. [2], [4], [10], [14], [15], [16], [18], [26] o [33], [37]
5.1.2 V
An essen ial pa o any design o a wooden b idge s uc u e is he choice o such an
a angemen o elemen s ha hey do no cause he in ake o ainwa e in o he
load-bea ing wooden o o he componen s. O he wise, he e is an acu e h ea ,
especially om so o .
Fig.
suppo ing s uc u e o he oo b idge is a double wooden gi de made o glued
beams wi h an in e media e b idge deck. The oo b idge is made o a sys em o
simple beams moun ed on pilla s and suppo s on s eel bea ings wi h a Te lon
su ace. The oo b idge consis s o 5 ields, while he i s and i h ields a e made
o wo uni o m ci cula a ches wi h a adius o 23 me e s, ields 2, 3, and 4 a e
54 Chap e 5
2022
Fig. 5.18 Leakage poin due o sla ed be els.
Fig. 5.19 Demons a ion o a sui able and unsui able solu ion. [11]
5.1.3
Wood can also be used o ligh en he s uc u e, making i possible o inc ease he
esul ing load-bea ing capaci y o he b idge s uc u e. This solu ion mainly b ings an
inc ease in le el, which a ec s subsequen communica ions.
. [12], [40]

Analysis o Selec ed B idge S uc u es in he Czech Republic 55
Analysis o Selec ed Li e Fac o s o Wooden B idges
The in es iga ed b idge is designed as a e ical b idge wi h one span. The suppo ing
s uc u e consis s o wo main s eel la ice gi de s. The b idge deck consis s o a s eel
c ossbeams sys em, LLD side membe s, and b idges. The c oss membe s a e made
o wo U280 p o iles welded a he join s o he main beams a axial dis ances o
2720 mm.
Longi udinals made o LLD GL24h wi h a ec angula c oss-sec ion wi h a wid h o
180 mm and a heigh o 360 mm a e placed on c ossba s a axial dis ances o 400
mm and 500 mm. The head o he longi udinal membe s is modi ied by a no ch 180
mm high. B idges made o g own oak d ied wood D30 a e placed on he longi udinal
membe s. The connec ion o he side membe s is made using coun e sunk sc ews.
A he same ime, he b idges o m a mo ing oad.
The subs uc u e consis s o wo conc e e abu men s wi h sloping dila ed wings.
B idge bea ings a e placed on s one s o age blocks loosely moun ed on s o age sills.
The subs uc u e does no a ec he load capaci y o b idges. [12], [40]
Fig. 5.21 Schema ic sec ion o he main b idge s uc u e. [12], [40]
Du ing a isual inspec ion o he b idge, s uc u al de ec s we e ound ha could
signi ican ly a ec i s load-bea ing capaci y o u he use. Longi udinal c acks we e
ound on he glued lamina ed imbe side membe s in he a ea o he no ch in he
place whe e he wooden side membe s we e placed on he s eel c ossbeams. These
c acks a e a ypical phenomenon when exceeding he shea capaci y o wood. In his
case, he phenomenon is exace ba ed by no ch, whe e shea s eng h dec eases
depending on he geome y o he no ch. The o ma ion o such c acks is ypical o
his ea men . [12], [40]
Diagnos ics
The ocus o he diagnos ics was mainly on he p ima y ailu e, which was he ailu e
o wooden elemen s by pulling pe pendicula o he ibe s due o shea , see ig. 5.22.
56 Chap e 5
2022
Fig. 5.22 Pho o documen a ion o he c ack in he longi udinal membe .
Based on he o iginal s a ic calcula ion, an assump ion was disco e ed ha could
was an e en dis ibu ion o
he load om he oad sec ion o he side membe s. The oad pa was o med by
oak ans e sely placed p isms D30, 120/160, which we e sc ewed di ec ly o he
longi udinal membe s.
P io o he diagnos ics i sel , a calcula ion o he FEM aid was pe o med, he subjec
o which was o de e mine he load dis ibu ion om he ehicle h ough he b idge
deck sec ion o he side membe s. The FEM model is based on he eal dimensions
and ma e ials o he damaged s uc u e. [12], [40]
40]
Analysis o Selec ed B idge S uc u es in he Czech Republic 57
Analysis o Selec ed Li e Fac o s o Wooden B idges
The sol ed longi udinal membe s we e selec ed based on he pe o med load es
indica ed on he diag am (see ig. 5.24).
Fig. 5.24 Scheme o dis ibu ion o senso s on moni o ed beams [12], [40]
Fig. 5.25 Placemen o s ing s ain gauges on he longi udinal membe . [12], [40]
A o al o 4 s ing s ain gauges we e used, wi h he ollowing dis ibu ion: he i s
senso eco ded he s ess di ec ly a he poin o p esumed ailu e by pulling
pe pendicula o he ibe s due o shea s ess. The o he 3 senso s we e loca ed on
58 Chap e 5
2022
he unde side in he middle o he spans. The layou and designa ion o he senso s
a e shown in ig. 5.25.
A loading ehicle acco ding o he design o he FEM model was used o he load.
The load dis ibu ion du ing he es was acco ding o he diag am in ig. 5.26.
Fig. 5.26 Schema ic load dis ibu ion du ing load es . [12], [40]
A e e alua ing he load es , see. [12], [40] he esul s we e compa ed wi h he
FEM model o de e mine he load dis ibu ion o indi idual longi udinal membe s.
Analysis o Selec ed B idge S uc u es in he Czech Republic 59
Analysis o Selec ed Li e Fac o s o Wooden B idges
Cha . 5.2 Pe cen age dis ibu ion o he load on he moni o ed elemen s.
The di e ences, which we e de e mined based on he FEM model and he IN-SITU
load es , a e in he o de o ens o pe cen . The cause o hese signi ican
di e ences may be he igidi y o he connec ion be ween he longi udinal membe s
and he b idge deck pa and he wood mass's inhomogenei y. Howe e , he damage
by so o was especially e ealed du ing he subsequen econs uc ion (see ig.
5.27).
Fig. 5.27 Damage o moni o ed beams. [12], [40]
The cause o he ailu e was hen e alua ed o so o , which o med unde he
insula ing oil. These ac s we e no known du ing he load es o du ing he
inspec ion o he s uc u e. The e was no indica ion o such a ailu e.
A B C
MKP 5,88 29,4 64,7
IN-SITU 3,4 17,9 78,7
0
10
20
30
40
50
60
70
80
90

60 Chap e 5
2022
Despi e he signi ican in luence o he ailu e o he beams by so o , i was p o ed
ha he load dis ibu ion on he longi udinal membe s om he b idge deck pa is
no uni o m. This p o ed he c ack, whe e he wood mass was b oken by pulling
pe pendicula o he ibe s due o shea o ces.
Analysis o Selec ed B idge S uc u es in he Czech Republic 61
Analysis o Selec ed Li e Fac o s o Wooden B idges
5.2 Analysis o Humidi y Condi ions
Wood mois u e is one o he decisi e ac o s in wooden elemen s' li e and
mechanical p ope ies. The e o e, 17 wooden b idge s uc u es, bo h mode n and
his o ical, we e moni o ed, o which su ace and in e nal humidi y depending on
empe a u e we e eco ded. The di e en humidi y a ios o he massi e load-
bea ing elemen s we e mainly moni o ed.
In e nal humidi y senso s, which a e p o ec ed as in ellec ual p ope y unde
numbe 32424, we e used o moni o ing. Fig. 5.28 shows a diag am o his senso ,
which uses he non-conduc i i y o he Te lon laye o de ec mois u e a he ip end
a a speci ic loca ion.
Fig. 5.28 Diag am o in e nal humidi y senso . [13]
Acco ding o he diag am, hese senso s we e placed in he suppo ing longi udinal
elemen s o he moni o ed s uc u es (see ig. 5.29).
Fig. 5.29 Scheme o measu ed poin s on moni o ed s uc u es.
In addi ion o he in e nal humidi y, su ace humidi y was also moni o ed in he
same place o de e mine he humidi y g adien . The ollowing equipmen was used
o his pu pose: "G eisinge GMH3810 wood mois u e me e ". [6], [13]
62 Chap e 5
2022
a) b)
Fig. 5.30a) BOSCH PTD1 b) G eisinge GMH3810.
Ano he moni o ed a iable was he ela i e humidi y o he ou side en i onmen
and empe a u e measu ed using: "BOSCH PTD 1 he mo-de ec o ". An addi ional
measu emen was ul asonic moni o ing o he p opaga ion speed o acous ic wa es
in he ma e ial. Wi h a pu pose o de e mine he es ima e o possible in e nal
damage and densi y o he ma e ial using: "Pulse ul asound TICO" using 54 kHz
p obes.
Fig. 5.31 Pulse ul asonic appa a us TICO. [12]
I is clea om he abo e diag am o ig. 299 loca ion o he p obes ha di ec pulsed
ul asonic measu emen was used. Rela ionships de ine he p opaga ion eloci ies
o he longi udinal and ans e se wa es.
(1)
(2)
Analysis o Selec ed B idge S uc u es in he Czech Republic 63
Analysis o Selec ed Li e Fac o s o Wooden B idges
In which: p longi udinal wa e p opaga ion eloci y (m.s-1),
s ans e se wa e p opaga ion speed (m.s-1),
0 bulk densi y o he ma e ial (kg.m-3),
Poisson's numbe (-),
Young's modulus o elas ici y (Pa).
I ollows om hese ela ions ha wa e speed p opaga ion does no depend on he
equency o he wa es bu only on he ma e ial pa ame e s o he en i onmen .
The e o e, he choice o sou ce equency du ing measu emen s does no a ec he
absolu e esul s bu only he "quali y" o he measu emen . The e is a loss o
ansmi ed ene gy (abso p ion) in a gi en en i onmen , which signi ican ly depends
on he equency o he wa es and humidi y, empe a u e, and o he pa ame e s
[19].
5.2.1 Leno a
I is a his o ic b idge whose load-bea ing s uc u e consis s o ough-hewn wooden
beams placed on a s one subs uc u e. The beam cons uc ion is wo-pole,
composed o simple beams. The uppe building is oo ed and clad along i s en i e
leng h, see ig. 5.32.
Fig. 5.32 Leno a b idge cons uc ion a e econs uc ion.
This building is loca ed on he ou ski s o he illage o Leno a a an al i ude o abou
755 m abo e sea le el and b idges he Wa m Vl a a in he Sou h Bohemian Region.
The s uc u e was buil in 1870, o which he subs uc u e and main suppo ing
beams ha e been p ese ed. The cladding and oo ing we e changed du ing se e al
econs uc ions.
70 Chap e 5
2022
Fig. 5.42 - ad anced delamina ion.
5.2.7
This suspension b idge b idges he E50 oad in he middle o he Buchlo hills. I s
load-bea ing s uc u e consis s o wo cu ed beams o glued lamina ed imbe
placed on he ein o ced conc e e subs uc u e. T ans e se ein o cemen is ealized
by he b idge deck pa (s eel c ossbeams and c oss-winding by ods - in e media e
b idge deck); see ig. 5.43.
The building lies a an al i ude o abou 546 m abo e sea le el and is loca ed in he
Sou h Mo a ian Region. The s uc u e was buil in 2011 and is made o sp uce wood.
The le uss a a dis ance o app ox. 1 m om he closing wall in he di ec ion o
he es s op was chosen as he moni o ing poin .

Analysis o Selec ed B idge S uc u es in he Czech Republic 71
Analysis o Selec ed Li e Fac o s o Wooden B idges
Ul.
su ace
Ul.
inne
Ul.
ai
Ul.
ai
e
mpe a u e
ul asonic
p opaga ion
speed
wid h
da
e
%
%
%
g.m
-
3
C
m.s
-
1
mm
23/7/
2018
15,3
19,9
55
12,67
25
-
220
20/11/
2018
16
15,7
44
1,807
-
2,1
1840
220
Tab. 5.8 Reco ded alues om diagnos ics.
- ad anced delamina ion.
Ad anced delamina ion is e iden in he cons uc ion o he main beams, see ig.
5.44, which co esponds o he age o he s uc u e.
5.2.8
This b idge s uc u e is loca ed nea he illage o Kuno ice. I s suppo ing s uc u e
consis s o wo s eel usses and c ossbeams. In o de o inc ease he load-bea ing
capaci y, a wooden b idge deck pa was designed du ing he econs uc ion, which
was made o longi udinal membe s made o glued lamina ed wood and b idges
made o oak wood (see ig. 5.45).
Fig. 5.45 b idge cons uc ion.
72 Chap e 5
2022
The building lies a an al i ude o abou 176 m abo e sea le el and b idges a ibu a y
o he Mo a ia
eno a ed in 2016.
The ex eme longi udinal sec ion a a dis ance o app ox. 1 m om he closing wall
in he di ec ion om he illage o Kuno ice was chosen as he place o obse a ion.
Ul.
su ace
Ul.
inne
Ul.
ai
Ul.
ai
e
mpe a u e
ul asonic
p opaga ion
speed
wid h
da
e
%
%
%
g.m
-
3
C
m.s
-
1
mm
23/7/
2018
16,6
21,1
55
13,63
26,3
-
250
20/11/
2018
16
19,9
54
2,496
-
0,6
1610
250
Tab. 5.9 Reco ded alues om diagnos ics.
The cons uc ion is in pe ec condi ion.
5.2.9
-bea ing s uc u e
consis s o wo cu ed beams o glued lamina ed imbe placed on he ein o ced
conc e e subs uc u e. T ans e se ein o cemen is ealized by he b idge deck pa
(s eel c ossbeams and c oss-winding by ods in e media e b idge deck); see ig.
5.46.
Fig. 5.46 idge cons uc ion.
The building lies a an al i ude o abou 299 m abo e sea le el and is loca ed in he
Mo a ian-Silesian egion. The s uc u e was buil in 2015 and is made o sp uce
wood.
The le uss a a dis ance o app ox. 1.5 m om he closing wall in he di ec ion o
Analysis o Selec ed B idge S uc u es in he Czech Republic 73
Analysis o Selec ed Li e Fac o s o Wooden B idges
Ul.
su ace
Ul.
inne
Ul.
ai
Ul. ai
e
mpe a u e
ul asonic
p opaga ion
speed
wid h
da
e
%
%
%
g.m
-
3
C
m.s
-
1
mm
4/
8
/
2018
13,6
20,1
58
13,69
27,5
1890
220
220
Tab. 5.10 Reco ded alues om diagnos ics.
The cons uc ion is in pe ec condi ion.
5.2.10
Thi
-bea ing s uc u e consis s o wo s aigh beams
o glued lamina ed imbe placed on he ein o ced conc e e subs uc u e.
T ans e se ein o cemen is ealized by he b idge deck pa (s eel c ossbeams and
c oss-winding by ods in e media e b idge deck); see ig. 5.47.
Fig. 5.47 .
The building lies a an al i ude o app oxima ely 495 m abo e sea le el and is loca ed
The le uss a a dis ance o app ox. 1 m om he closing wall in he di ec ion o
he E442 oad was chosen as he moni o ing poin .
Ul.
su ace
Ul.
inne
Ul.
ai
Ul. ai
e
mpe a u e
ul asonic
p opaga ion
speed
wid h
da
e
%
%
%
g.m
-
3
C
m.s
-
1
mm
4/8/
2018
15,6
42,5
61
15,54
26,8
-
-
-
Tab. 5.11 Reco ded alues om diagnos ics.
74 Chap e 5
2022
Fig. - biological damage.
Each suppo ing beam is composed o a pai o glued lamella usses, be ween
which i lows, and hanks o his, he e was an a ack by wood-des oying insec s,
see ig. 5.48.
5.2.11
-bea ing s uc u e consis s o
wo s aigh beams o glued lamina ed imbe placed on he ein o ced conc e e
subs uc u e. T ans e se ein o cemen is ealized by he b idge deck pa (s eel
c ossbeams and c oss-winding by ods - in e media e b idge deck) see ig. 5.49.
Fig. 5.49 b idge cons uc ion.
The building lies a an al i ude o abou 484 m abo e sea le el and is loca ed in he
The le uss a a dis ance o app ox. 1 m om he closing wall in he di ec ion o
The cons uc ion shows no signs o damage.
Analysis o Selec ed B idge S uc u es in he Czech Republic 75
Analysis o Selec ed Li e Fac o s o Wooden B idges
Ul.
su ace
Ul.
inne
Ul.
ai
Ul. ai
e
mpe a u e
ul asonic
p opaga ion
speed
wid h
da
e
%
%
%
g.m
-
3
C
m.s
-
1
mm
4/8/
2018
16,4
23,8
61
14,45
25,5
-
-
-
Tab. 5.12 Reco ded alues om diagnos ics.
5.2.12 1
This wood-conc e e beam oo b idge is loca ed on he ou ski s o he illage
wooden beams made o lamina ed wood and a conc e e slab ha can be d i en
di ec ly. The ho izon al s uc u e is placed on he ein o ced conc e e subs uc u e.
The b idge deck pa ealizes ans e se ein o cemen ( ein o ced conc e e slab);
see ig. 5.50.
Fig. 5.50 b idge cons uc ion.
The building lies a an al i ude o abou 338 m abo e sea le el and is loca ed in he
Cen al Bohemian Region. The s uc u e was buil in 2017 and is made o sp uce
wood.
The igh uss a a dis ance o app ox. 1.5 m om he closing wall in he di ec ion o
Ul.
su ace
Ul.
inne
Ul.
ai
Ul.
ai
e
mpe a u e
ul asonic
p opaga ion
speed
wid h
da
e
%
%
%
g.m
-
3
C
m.s
-
1
mm
6/8/
2018
11,3
18,5
74
20,69
28,5
1980
200
20/11/
2018
15,6
14,1
41
2,074
0,6
1870
200
Tab. 5.13 Reco ded alues om diagnos ics.

76 Chap e 5
2022
The cons uc ion shows no signs o damage.
5.2.13
This wood-conc e e beam oo b idge is loca ed on he ou ski s o he illage
o ing s uc u e consis s o
wooden beams made o lamina ed wood and a conc e e slab ha can be d i en
di ec ly. The ho izon al s uc u e is placed on he ein o ced conc e e subs uc u e.
The b idge deck pa ( ein o ced conc e e slab) ealizes ans e se ein o cemen
(see ig. 5.51).
Fig. 5.51 b idge cons uc ion.
The building lies a an al i ude o abou 338 m abo e sea le el and is loca ed in he
Cen al Bohemian Region. The s uc u e was buil in 2017 and is made o sp uce
wood.
The igh uss a a dis ance o app ox. 1.5 m om he closing wall in he di ec ion o
Ul.
su ace
Ul.
inne
Ul
.
ai
Ul.
ai
e
mpe a u e
ul asonic
p opaga ion
speed
wid h
da
e
%
%
%
g.m
-
3
C
m.s
-
1
mm
06/08/
2018
10,9
18,2
74
22,69
30,2
1920
200
20/11/
2018
14,3
14,4
54
2,435
-
0,9
1950
200
Tab. 5.14 Reco ded alues om diagnos ics.
The cons uc ion shows no signs o damage.
5.2.14 -B no
This a ched oo b idge is b idging he i e S i a a. I s suppo ing s uc u e consis s
o wo a ched beams o glued lamina ed imbe placed on he ein o ced conc e e
Analysis o Selec ed B idge S uc u es in he Czech Republic 77
Analysis o Selec ed Li e Fac o s o Wooden B idges
subs uc u e. T ans e se ein o cemen is ealized by he b idge deck pa (s eel
c ossbeams and c oss-winding by ods - in e media e b idge deck); see ig. 5.52.
Fig. 5.52 B no b idge cons uc ion.
The building lies a an al i ude o abou 272 m abo e sea le el and is loca ed in he
Sou h Mo a ian Region. The s uc u e was buil in 2012 and is made o sp uce wood.
The le uss a a dis ance o app ox. 1.3 m om he closing wall in he di ec ion o
he cen e o B no was chosen as he moni o ing poin .
Ul.
su ace
Ul.
inne
Ul.
ai
Ul.
ai
e
mpe a u e
ul asonic
p opaga ion
speed
wid h
da
e
%
%
%
g.m
-
3
C
m.s
-
1
mm
23/07/
2018
11,8
24,4
46
9,036
22,2
1530
280
20/11/
2018
15,5
21,5
48
2,377
0,3
1540
280
Tab. 5.15 Reco ded alues om diagnos ics.
-B no b idge cons uc ion - ad anced delamina ion.
78 Chap e 5
2022
Ad anced delamina ion is e iden in he cons uc ion o he main beams, see ig.
5.53, which co esponds o he age o he s uc u e.
5.2.15
I is a his o ic b idge whose load-bea ing s uc u e consis s o ough-hewn wooden
beams placed on a s one subs uc u e. The beam cons uc ion is wo-pole composed
o simple beams. The uppe building is oo ed and clad along i s en i e leng h, see
ig. 5.54.
Fig. 5.54 b idge cons uc ion.
m abo e sea le el and b idges he S a ka Ri e in he Sou h Mo a ian Region. The
s uc u e was buil in 1718. The cladding and oo ing we e changed du ing se e al
econs uc ions.
The o iginal wooden beam, which b idges he i s ield owa ds he cen e o he
illage and is loca ed on he middle beam o he ans e se span, was chosen o
obse a ion.
Ul.
su ace
Ul.
inne
Ul.
ai
Ul.
ai
e
mpe a u e
ul asonic
p opaga ion
speed
wid h
da
e
%
%
%
g.m
-
3
C
m.s
-
1
mm
20/08/
2018
16
22,6
50
8,648
20
1830
320
18/11/
2018
17,3
16,3
49
2,44
0,4
1770
320
Tab. 5.16 Reco ded alues om diagnos ics.
5.2.16
This beam oo b
o
glued lamina ed imbe placed on he ein o ced conc e e subs uc u e. T ans e se
Analysis o Selec ed B idge S uc u es in he Czech Republic 79
Analysis o Selec ed Li e Fac o s o Wooden B idges
ein o cemen is ealized by he b idge deck pa (s eel c ossbeams and c oss-
winding by ods - in e media e b idge deck); see ig. 5.55.
Fig. 5.55 b idge cons uc ion.
The building lies a an al i ude o abou 325 m abo e sea le el and is loca ed in he
Sou h Mo a ian Region. The cons uc ion was made o sp uce wood.
The le uss a a dis ance o app ox. 1 m om he closing wall in he di ec ion o
Ul.
su ace
Ul.
inne
Ul.
ai
Ul.
ai
e
mpe a u e
ul asonic
p opaga ion
speed
wid h
da
e
%
%
%
g.m
-
3
C
m.s
-
1
mm
27
/08/
2018
11,9
21,6
50
8,543
19,8
-
220
20/11/
2018
14,5
22,3
46
2,537
1,9
-
220
Tab. 5.17 Reco ded alues om diagnos ics.
Fig. 5.56 The b idge cons uc ion in ice delamina ion.
86 Chap e 6
2022
The pe o med expe imen is based on s a ic ic ion, which ensu es ope a ional
sa e y, signi ican ly highe load capaci y, and lowe de o ma ion han in he case o
kinema ic ic ion.
a) b)
Fig. 6.7 a) axonome y o he expe imen al sample, b) sec ion o he expe imen al
sample, (1 U-shaped wooden elemen , 2 T-shaped conc e e elemen ,
3 p es essing elemen s.
Fo he p oposed expe imen al elemen , see ig. 6.7 uses he connec ion o a T-
shaped conc e e p o ile and a U-shaped wooden elemen , which o ms a wood-
conc e e beam du ing he connec ion, while he wooden elemen s also o m a
hidden o mwo k. This solu ion makes i possible o in oduce ans e se
p es essing o ces a e he conc e e has ha dened, which ensu es he connec ion
be ween he elemen s by ic ion. The ic ion o ce can be a ied depending on he
applied p eload.
Po e loned as ene s we e used o allow con ollable p es essing. The ad an age o
his solu ion is he emo al o he lub ican , which can bind impu i ies and hus
signi ican ly change he esul ing alues o he applied p es essing o ces using a
o que w ench. I a lub ican is used, i o en loa s ou , and subsequen igh ening
no longe gua an ees he equi ed p es essing o ces. Po e loned means
gua an eeing cons an condi ions du ing p es essing and he possibili y o epea ed
p ocesses o e ime.

Possible Solu ions o Sho Li e 87
Analysis o Selec ed Li e Fac o s o Wooden B idges
Fig. 6.8 Te lona ed as ene s.
Be o e p es essing, es s we e pe o med o calib a e he as ene s co e ed wi h
Te lon. The same assembly ha was used in he wood-conc e e beam expe imen
was calib a ed. The assembly consis ed o a bol , wo la ge- o ma washe s, and
nu s.
Fig. 6.9 Measu ing se .
The measu ing se included a We a 7100 se ies o que w ench, an Ahlbo n Almemo
2690 con ol panel, and an FKA613 o ce senso . The aim was o pe o m se e al
successi e igh enings on a se ies o 3 assemblies so ha i was possible o compile
88 Chap e 6
2022
a calib a ion g aph o he dependence o he igh ening o que on he p es essing
o ce.
G aph 6.1 Dependence o he igh ening o que on he p es essing o ce.
G aph 6.1 shows ha he 1.0 and 2.0 se ies a e almos iden ical. The only di e ence
is he 3.0 se ies, which was assembled om elemen s p oduced in a di e en se ies.
G aph 6.2 Dependence o he igh ening o que on he p es essing o ce o s a es
1-4.
Possible Solu ions o Sho Li e 89
Analysis o Selec ed Li e Fac o s o Wooden B idges
G aph 6.2 desc ibes he dependence o he p es essing o ce on he igh ening
o que o he indi idual s a es. Condi ion 1 desc ibes he a e age alues
co esponding o he i s igh ening. Each addi ional condi ion co esponds o a
subsequen elease and e igh ening. The dec ease in p es essing o ce due o wea
o he ic ion su aces be ween he i s and second igh ening (s a e 1 and s a e 2)
co esponds o almos 30% (28.72%). Subsequen s eps di e minimally, always wi h
a dec ease in p es essing o ce o abou 1%.
Thanks o he pe o med calib a ion o he igh ening o que and p es essing o ce
o Te lon join s, i was subsequen ly possible o pe o m a co ec p es essing o
he expe imen .
The expe imen was se up based on p elimina y calcula ions and nume ical models
o be pe o med in a con olled labo a o y en i onmen . The moni o ed sample
om he KVH p o ile, s eng h class C24, consis ed o h ee wooden elemen s
measu ing 60x280 mm x 2 and one elemen 60x180 mm. A e assembly, hese
elemen s o m a U-shape and los o mwo k a he same ime (see ig. 6.8). C40 / 45
T-shaped conc e e mixe has boa d dimensions o 180x100mm and webs o
60x100mm. The conc e e ein o cemen was p o ided by a welded wi e mesh o
100x100 mm wi h a diame e o 6 mm o ensu e he ansmission o shea o ces
(see ig. 6.8).
Fig. 6.8 Rein o cemen o he expe imen al wood-conc e e sample.
To de e mine he esul ing dimensions and mass dis ibu ion o wood and conc e e,
he o ce sum condi ions o he balance o o ces in he c oss-sec ion we e used:
, (4)
whe e he alue o Fc1 co esponds o he comp essi e o ce in he conc e e
T-sec ion slab. Fc2 indica es he comp essi e o ce in he web sec ion o he conc e e
T sec ion. In he p o ile, can be a p essu e e ec on he U-p o ile wooden pa , which
is in oduced in he o mula by he alue Fw1. On he igh side, while neglec ing he
possibili y o ensile ac ion o he conc e e T-p o ile, only he d awn pa o he
90 Chap e 6
2022
wooden p o ile U emains, which is in oduced by he alue Fw2. When placed in he
o ce condi ion o equilib ium, we ge he o mula:
, (5)
whe e ck is he cha ac e is ic comp essi e s eng h o conc e e, be he elec i e
wid h, and hc he slab hickness. Fu he mo e, he o mula con ains b - web wid h
T c oss-sec ion, c0k - cha ac e is ic wood comp essi e s eng h, 0k - cha ac e is ic
wood comp essi e s eng h, h1 - he heigh o he middle wooden elemen , h - he
heigh o ex eme wooden p o iles U. The only unknown is he alue x, which
indica es he posi ion o he neu al axis o he idealized c oss-sec ion.
(6)
Op imal dimensions and ma e ials we e designed based on he idealized wood-
conc e e c oss-sec ion's de e mined neu al axis. A neu al axis is also an ideal place
o moun ing he ans e se p es essing o he p o ile.
Fig. 6.9 Fi ing he expe imen al wood-conc e e sample in o a es bench.
The elemen designed in his way was i ed wi h a ans e se p eload a he loca ion
o he assumed neu al axis. Based on he assump ion o elas ici y heo y, he
p es essing elemen s we e ins alled acco ding o he alues o longi udinal shea :
, (7)
whe e VEd is he design alue o he shea o ce, Sc is he s a ic momen o he a ea
o he p essed pa o he conc e e slab o he neu al axis o he idealized c oss-
sec ion, and I1 is he momen o ine ia o he idealized c oss-sec ion. Ano he
c i e ion o he placemen o p es essing elemen s was he size o he washe s and
he dis ibu ion o p es essing o ces in he wood-conc e e in e ace. The maximum
p es essing o ces a e always limi ed by he size o he base so ha he wood mass
Possible Solu ions o Sho Li e 91
Analysis o Selec ed Li e Fac o s o Wooden B idges
is no damaged by p essu e pe pendicula o he ibe s. When using la ge- o ma
hick-walled 60 HRC ha dened s eel washe s, he a e age p eload co esponded o
app ox. 17.5 kN wi h an a e age igh ening o que o app ox. 65 Nm. Acco ding o
he dis ibu ion o p es essing elemen s and he in oduc ion o p es essing, he
heo e ical ic ion o ce on he beam was de e mined o be app oxima ely 146 kN.
To ensu e he p ope unc ionali y o he s uc u e, he condi ion mus be me :
. (8)
The p ima y goal o he wood-conc e e beam expe imen using ic ional o ces was
p ima ily o de e mine he EIe alue, which depends on many ac o s, including he
p ope ies o conc e e and wood. The unknown ac o is mainly he a e o ic ion
sledding.
Fou -poin bending was used o s a ic loading o he expe imen al sample. This ype
o loading was used mainly due o he heo e ically cons an shea s ess in he i s
and las hi d o he span, which is sui able o es ing he coupling o which shea
is c ucial.
The loading was ealized using a hyd aulic de ice in s ep o ce inc emen s wi hou a
elie cycle. The indi idual s eps we e chosen a 20 kN un il ailu e. A each s ep, he
moni o ed alues we e ead, including de lec ion in he middle o he span, p essu e
in he suppo s, comp essi e o ce, and ension o he lowe and uppe ibe s (see
ig. 6.9).
G aph 6.3 Resul ing g aph o de o ma ion e sus load.
0
20
40
60
80
100
120
0 2 4 6 8 10 12 14 16

92 Chap e 6
2022
G aph 6.3 desc ibes he dependence o he de o ma ion in he middle o he beam
on he o al o ce o he hyd aulic comp ession pis ons du ing ou -poin bending.
This g aph desc ibes an almos ideal linea cu e e mina ed by slippage in he
ans e se p es essing ic ion join s a a o ce o 103 kN and de o ma ion o
15.01 mm. Du ing he slip, he sample did no b eak only in he ab up change om
s a ic o kinema ic.
G aph 6.4 Resul ing g aph o s i ness and o ce dependence.
An essen ial pa ame e is he elemen 's s i ness unde load, desc ibed in igu e 6.4.
The s i ness du ing he whole load is e y s able, wi h a maximum ange o 8.88%
and an a e age alue o a ound 6900 kN / m.
comp essi e o ce
sag
igidi y
-
conc e e
-
wood
[kN
]
[mm
]
[kN/m
]
[MPa
]
[MPa
]
0
0
0
0
0
23
3,51
6553
-
10,28
6,41
43
6,25
6880
-
18,33
12,10
63
8,76
7192
-
27,56
16,87
83
11,83
7016
-
36,94
21,87
103
15,01
6862
-
47,33
26,31
Tab. 6.1 Da a ob ained om he load es o an expe imen al wood-conc e e
sample.
Table 6.1 lis s all he alues ob ained and calcula ed in he s a ic load es o he
expe imen al wood-conc e e sample.
0
1000
2000
3000
4000
5000
6000
7000
8000
0 20 40 60 80 100 120
F[kN]
Possible Solu ions o Sho Li e 93
Analysis o Selec ed Li e Fac o s o Wooden B idges
Based on his pilo expe imen al es , basic in o ma ion and pa ame e s o s a ing
a se ies o es s we e ob ained. These a e mainly he alues needed o a mo e
accu a e design o o he expe imen al es s such as (EI) e .
Fig. 6.10 Idealized s ess diag am o wood-conc e e composi e elemen s.
Suppose we use an idealized assump ion abou he beha io o wood-conc e e
composi e elemen s. In ha case, i is possible o de e mine by back analysis, o
example, he alues o he modulus o slip Kse .
(9)
When changing he p eload, i is also possible o assume a change in he Kse slip
module. The deg ee o p es essing applied depends mainly on he p es essing
o ce, which can be a decisi e ac o compa ed o o he coupling means. [1], [7], [21]
o [23]
94 Chap e 6
2022
6.2 Composi e Ma e ials
The bes -known composi e in cons uc ion is ein o ced conc e e, which uses he
ensile s eng h o s eel in he d awn pa o he elemen , and conc e e is used o
ans e comp essi e o ces. Toge he , hese ma e ials wo k due o simila he mal
longi udinal expansion. Despi e s eel's high comp essi e and ensile s eng hs,
ein o ced conc e e elemen s a e mo e economically ad an ageous han i each
ma e ial we e used sepa a ely due o he connec ion wi h conc e e.
The same p inciple can be applied o inc ease he se ice li e o wooden elemen s
on b idge s uc u es. The basic ule is o p e en ainwa e om lowing in o he
wooden p o iles, which subsequen ly inc eases he humidi y and he possibili y o
a ack by biological pes s. The se ice li e can hus be educed by decades, as shown
by long- e m moni o ing o selec ed s uc u es (see chap. 5.1).
Among he adi ional ways o insula e wooden beams agains ainwa e is coa ing
insula ion (ca dboa d, oil) o pla ing. Insula ion is always applied only om he op
so ha he e can be an exchange o mois u e be ween he wood and he
en i onmen . These common insula ion sys ems can cause local ailu es, such as
insula ion ailu e. In some cases, mois u e can e apo a e om he wood elemen
di ec ly unde he insula ion, causing condensa ion o occu , which can cause an
inc ease in humidi y and subsequen ailu e.
a) b)
Fig. 6.11a) a ian wi h insula ing oil b) a ian wi h pla ing.
Faul unde insula ion is, in mos cases, e y p oblema ic o iden i y. Due o
condensa ion on he unde side o he insula ion, i lows in o he lowes place o
a ea.
Possible Solu ions o Sho Li e 95
Analysis o Selec ed Li e Fac o s o Wooden B idges
Fig. 6.12 Faul unde he insula ion on he side membe .
Fig. 6.12 shows a aul ha was caused by condensa ion unde he insula o and
subsequen biological a ack by so o . This damage occu ed a e only 3 yea s o
ope a ion. In addi ion o weakening he beam, he join s o he adjoining elemen s
we e also loosened.
A possible al e na i e ha could elimina e he exis ing condensa ion p oblem is a
composi e composed o a ca ie (wood) and a con ac insula o (polyu ea). The
main equi emen s o he insula o a e cohesi eness, su icien lexibili y, and wa e
igh ness.
Polyu ea ma e ial was chosen as he insula ing elemen . I is a highly lexible, wo-
componen polyme sys em ha can be used on ma e ials such as s eel, conc e e,
and wood. The applica ion is ca ied ou using special high-p essu e ho pumps. The
mixing componen s (amines and isocyana es) a io is 1: 1. The sys em is
cha ac e ized by i s as cu ing in he o de o se e al ens o seconds. The insula ion
has e y good mechanical pa ame e s (adhesion o he subs a e, ensile s eng h,
elonga ion). Ano he ad an age is he UV esis ance o he ma e ial.
A composi e composed o wood and polyu ea may be sui able o wooden b idges
and oo b idges. Thanks o his solu ion, condensa ion, and subsequen aul s should
be p e en ed. The main bene i would be o inc ease he se ice li e by decades.
The unce ain y o he op imal unc ion lies p ima ily in he ai igh sealing o he
wood su ace. The p e en ion o he possibili y o e apo a ion, and he ing ess o
mois u e, depending on he ex e nal en i onmen .
6.2.1 Labo a o y Measu emen s
Th ee ypes o expe imen al measu emen s we e pe o med wi hin he labo a o y
e i ica ion o he se assump ions.
102 Chap e 6
2022
The selec ed beam was chosen in he i s ield a he edge o he ans e se span.
This place was chosen because o he expec ed mos signi ican load o wea he and
humidi y. The measu emen was s a ed in No embe 2016 a e he beam was
ins alled in he s uc u e.
G aph 6.8 Cou se o humidi y condi ions on he moni o ed s uc u e.
When ins alling he senso s, he humidi y o he en i e selec ed beam was measu ed.
Because he beam was di ec ly exposed o hea y p ecipi a ion du ing anspo ,
ins alling he insula ion sys em on he d ie side was necessa y, whe e he humidi y
was a ound 14% du ing ins alla ion. On he opposi e side o he c oss-sec ion, a alue
o app ox. 46% was measu ed, see ig. 6.21.
Fig. 6.21 Reco ding o excessi e humidi y be o e ins alla ion o senso s (45.6%).
0
5
10
15
20
25
30
XI.16 I.17 III.17 V.17 VII.17 IX.17 XI.17 I.18 III.18 V.18 VII.18 IX.18 XI.18
XI.16 I.17 VIII.17 I.18 VII.18 XI.18
ex e nal 15,5 16,8 15,95 16,55 16,1 15,95
in e nal 13,9 15,8 26,15 24,05 21 19,65

Possible Solu ions o Sho Li e 103
Analysis o Selec ed Li e Fac o s o Wooden B idges
A e ins alling he beam on he s uc u e in he win e , when he ela i e humidi y
and empe a u e a e low, he in e nal humidi y emained a ound 16.5%, and he
su ace humidi y g adually dec eased. A he onse o high summe empe a u es,
he in e nal humidi y shi ed ou wa ds om he p o ile. A he same ime, he
mois u e hi he insula ion sys em, hanks o which he humidi y unde he insula ion
inc eased ab up ly. This mois u e does no a ec he cohesion o he composi e, bu
long- e m exposu e could lead o in es a ion by wood-des oying pes s. In he
ollowing pe iod, he c oss-sec ion d ied na u ally, which also posi i ely a ec ed he
in e nal humidi y unde he insula ion. Assuming ha he cu en end emains,
he e is a p esump ion o p o e he wood-polyu ea composi e's op imal unc ioning.
Suppose he long- e m unc ionali y o his sys em is p o en in p ac ice. In ha case,
i will be possible o con ibu e o be e p o ec ion and a signi ican inc ease in he
se ice li e o wooden b idge s uc u es.
105
7 Discussion, conclusion
This wo k ies o answe he undamen al ques ion o he low se ice li e o some
wooden b idge s uc u es in he Czech Republic. Despi e he exis ing heo e ical
o ien a ion p ocedu es, how o de e mine he se ice li e o wooden b idge
s uc u es, hese me hods a e only a quali ied es ima e. One o hese me hods is, o
example, he Fac o Me hod (ISO 15686-1), which is desc ibed in de ail in he
li e a u e. Based on his me hod, he se ice li e o an unco e ed s uc u e is a ound
40 yea s and o a oo ed s uc u e a ound 150 yea s [27].
The p obable cause o he low se ice li e o some cu en wooden b idge s uc u es
is non-compliance wi h one o mo e ules o he du abili y o hese s uc u es,
which a e known om he p ese ed his o ic s uc u es. These a e mainly:
selec ion o a sui able ma e ial (la ch o s uc u es, oak o he oad pa ) ;
;
ensu ing op imal humidi y (in e nal wo
I hese condi ions a e no ensu ed, he e may be a signi ican educ ion in se ice
li e, as wi h he s uc u es lis ed in chap. 5.1. I he basic ules o design, cons uc ion,
and adminis a ion a e no obse ed, he se ice li e is educed o abou 10 yea s.
These cons uc ions also include he cons uc ion o a oo b idge in he illage o
S unko ice, which was made o glued lamina ed imbe , which ensu ed he
condi ion o d yness o he buil -in ma e ial.
Fig. 7.1 Condi ion o he wooden oo b idge in he illage o S unko ice a e 8 yea s.
Howe e , wo o he condi ions we e no ensu ed, and he e o e, a e en yea s, his
s uc u e was eplaced by a s eel s uc u e. Du ing he cons uc ion o he s eel
s uc u e, he suppo ing s uc u e was no longe included in he soil, which was he
main cause o he des uc ion o he o iginal wooden oo b idge, and i s se ice li e
is es ima ed a decades.
106 Chap e 7
2022
The knowledge o he p o essional public in he ield o design and managemen o
s eel o conc e e s uc u es is p obably decisi e o e he las mo e han 100 yea s o
expe ience. Wooden b idges and oo b idges in he Czech Republic ha e a mode n
his o y o app oxima ely 20 yea s. I belie e ha his di e ence in he knowledge and
expe ience o he p o essional public is a decisi e ac o in he issue o he se ice
li e o wooden b idges and oo b idges in he Czech Republic.
The ollowing answe s o he undamen al ques ions aims o con ibu e o he design
and implemen a ion o imbe s uc u es ha will las o ens o hund eds o yea s,
as his o y shows ha imbe s uc u es can compe e success ully wi h conc e e o
s eel s uc u es in he long un.
Discussion, conclusion 107
Analysis o Selec ed Li e Fac o s o Wooden B idges
7.1 The Quali y o he Wood Used
Wooden b idge cons uc ions a e being buil all o e he wo ld. F om he a ailable
sou ces, i is clea [3], [11], [27] ha wooden b idge cons uc ions can las o
hund eds o yea s. Wood is a local aw ma e ial ha a ies mo e o less by egion.
This wo k was ocused mainly on he locali y o he Czech Republic, whe e i is
possible o ind hund eds o wooden b idge s uc u es and dozens o his o ic
buildings whose age is mo e han 100 yea s.
The quali y o wood can be moni o ed om many pe spec i es, including mechanical
p ope ies, du abili y, esis ance o biological pes s, and o he s, desc ibed in de ail
in he li e a u e [11], [27].
All moni o ed mode n b idge s uc u es in he Czech Republic a e made o sp uce
wood, see chap. 5.5. The p obable a gumen o his monopoly is he p ice and
a ailabili y o sp uce lumbe in a gi en locali y. Assuming he simila i y o he
ha dness p ope ies o sp uce wood in Cen al Eu ope, which can be e i ied in he
ield using he ul asonic me hod, i is possible o compa e wi h his o ic s uc u es,
whose du abili y is p o en by hei exis ence.
Mode n wooden b idge s uc u es whose age does no exceed 10 yea s we e
selec ed o moni o ing, see chap. 5.2. The e we e a o al o 8 moni o ed
cons uc ions wi h a maximum o 1980 ms-1 a he wood-conc e e oo b idge in
-1
(2012). The a e age alue o all moni o ed s uc u es is he speed o p opaga ion o
ul asonic wa es 1780 ms-1. I is necessa y o add ha hese cons uc ions ha e no
majo de ec s and a e a he beginning o hei li e. When compa ed o his o ic
buildings, whe e he a e age alue eaches 1840 ms-1, he quali y o he ma e ial
when compa ing he speed o p opaga ion o ul asonic wa es is o he de imen o
mode n buildings. This compa ison is inco ec due o he cons uc ion o his o ic
buildings hund eds o yea s ago om la ch wood, whose s eng h and du abili y a e
highe han ha o sp uce wood [1]. Based on he moni o ing o h ee his o ic b idge
s uc u es, i is clea ha o e ime he e is no signi ican dec ease in he densi y o
he ma e ial, so ha i has a signi ican e ec on he mechanical p ope ies.

108 Chap e 7
2022
7.2 En i onmen al Impac
As an o ganic, inhomogeneous, aniso opic and hyg oscopic ma e ial, wood is
in luenced by he ex e nal en i onmen . The mois u e con en o wood, which is
long- e m depending on he ex e nal en i onmen , is a signi ican in luence. The
mois u e con en o he wood a ec s he mechanical p ope ies and he se ice li e
o he s uc u e. The isk limi o wood mois u e is associa ed p ima ily wi h he
occu ence o biological pes s. This is he p ima y isk ega ding he longe i y o
wooden b idge s uc u es, which can cause se ious ailu es in a ela i ely sho
pe iod. The ins alla ion o und ied wood is haza dous, despi e mode n
imp egna ions, see chap. 5.1.1. Thanks o he gluing echnology, mode n
cons uc ions made o glued lamina ed wood ensu e ha he wooden elemen s a e
p e-d ied be o e being buil in o he s uc u e. The de elopmen o he ex e nal
en i onmen o he humidi y o glued lamina ed imbe s uc u es was moni o ed
on 14 mode n b idge s uc u es, which a e up o 10 yea s old, and h ee his o ical
s uc u es, see chap. 5.2. The ollowing g aphs always show he alues o su ace
mois u e measu ed on he su ace o he s uc u e and he in e nal humidi y, which
was moni o ed inside he p o ile see chap. 5.2.
G aph 7.1 Dependence o empe a u e on ma e ial humidi y in summe .
G aph 7.1 shows he ex e nal and in e nal humidi y o he moni o ed s uc u es a
di e en empe a u es in he summe , which b ings highe absolu e humidi y. I we
in e pola e he poin s wi h a linea unc ion, we dec ease humidi y wi h inc easing
empe a u e in bo h cases. Based on his g aph, i is possible o conside a sligh
d ying o he su ace and in e nal wood mass. In he case o mois u e abo e 30% o
he in e nal ma e ials, incipien de ec s we e ound in he s uc u e.
Discussion, conclusion 109
Analysis o Selec ed Li e Fac o s o Wooden B idges
G aph 7.2 Dependence o absolu e ambien humidi y on ma e ial humidi y in
summe .
G aph 7.2 shows he mois u e con en o he wood (su ace, indoo ) a he absolu e
humidi y o he en i onmen . The g aph shows ha he wood d ies ou e en wi h
inc easing absolu e humidi y. F om he abo e ac s, i can be said ha empe a u e
is a signi ican ac o in luencing he humidi y o wood in he summe .
G aph 7.3 Dependence o empe a u e on ma e ial humidi y in win e .
110 Chap e 7
2022
The dependence o ex e nal empe a u e and humidi y o wood is shown in g aph
7.3. He e i is clea ha as he empe a u e d ops, he humidi y also d ops. This is
he opposi e phenomenon as in he summe pe iod, whe e he humidi y o he wood
dec eased wi h inc easing empe a u e.
G aph 7.4 Dependence o absolu e humidi y on ma e ial humidi y in win e .
G aph 7.4 eco ds he wood mois u e alues o he espec i e absolu e ambien
humidi y. I is clea om he g aph ha wi h dec easing absolu e humidi y, he e is
also a dec ease in wood mois u e, whe e a sha p dec ease occu s in he humidi y o
he inne ma e ial. I is, he e o e, possible o claim ha , in addi ion o he
dec easing empe a u e, he absolu e en i onmen humidi y also a ec s he d ying
o wood.
Impo an g aph 7.5 shows he dependence o he wood mois u e g adien
(di e ence be ween summe and win e humidi y) and he absolu e ambien
humidi y g adien (di e ence be ween summe and win e g adien ). F om he
linea cu e co esponding o he ex e nal (su ace) humidi y, he inc ease in he
wood mois u e g adien in absolu e alue wi h he inc ease in he absolu e humidi y
g adien o he en i onmen is e iden . The g ea e he d op in absolu e humidi y o
he ex e nal en i onmen , he g ea e he inc ease in humidi y. While o indoo
humidi y, i is he opposi e. The g ea e he absolu e humidi y g adien , he g ea e
he mois u e loss inside he ma e ials.
Discussion, conclusion 111
Analysis o Selec ed Li e Fac o s o Wooden B idges
G aph 7.5 Dependence o he absolu e humidi y g adien on he wood mois u e
g adien .
The abo e da a also makes i possible o de e mine he di e ence be ween ou doo
and indoo humidi y in di e en seasons. This is an a e age di e ence o 8.88% o
he summe pe iod, while his di e ence in he win e pe iod is only 5%. This
condi ion is caused by an inc ease in su ace mois u e and a dec ease in in e nal
humidi y in win e .
G aph 7.6 Compa ison o alues om g aph 1.1 wi h eally measu ed da a in
summe .
118 Li e a u e
2022
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Li e a u e 119
Analysis o Selec ed Li e Fac o s o Wooden B idges
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