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CLIMATE-DRIVEN STRUCTURAL DETERIORATION MODELS FOR
REINFORCED CONCRETE BRIDGES: A CASE STUDY OF THE IMO RIVER
BRIDGE, NIGERIA
Nnamdi P. Ogbonna1,
Oladapo A. Mo akinyo2
1,2 Lec u e , Ci il Enginee ing Depa men , Fede al Poly echnic Nekede, Owe i, Nige ia
nopso [email protected]
ABSTRACT
B idges in opical en i onmen s a e inc easingly ulne able o clima e-induced de e io a ion, ye limi ed
localized s udies exis o quan i y he long- e m impac s o clima ic s esso s on s uc u al pe o mance. This
esea ch in es iga es he in luence o clima e a iables on he po en ial de e io a ion o he Imo Ri e B idge, a
ein o ced conc e e s uc u e in sou he n Nige ia. Daily me eo ological da a—including ain all, empe a u e,
ela i e humidi y, and wind speed—we e ex ac ed om he NASA POWER sa elli e da abase o a 30-yea
pe iod and analyzed o es ablish clima ic ends ele an o ma e ial deg ada ion. The analysis e eals signi ican
inc eases in annual ain all and sus ained pe iods o high ela i e humidi y, condi ions ha accele a e
ein o cemen co osion, conc e e c acking, and loss o s uc u al se iceabili y. Compa a i e assessmen wi h
li e a u e-based de e io a ion models o opical b idges indica es a c i ical esea ch gap in p edic i e modeling
o Nige ian in as uc u e unde clima e s ess. This s udy he e o e p oposes a amewo k ha in eg a es
clima ic da a wi h s uc u al de e io a ion models o o ecas se ice li e and in o m main enance s a egies. The
indings con ibu e o he g owing body o knowledge on clima e- esilien in as uc u e, o e ing p ac ical
insigh s o policymake s, enginee s, and asse manage s in de eloping egions.
Keywo ds:
Clima e, S uc u al De e io a ion, Models, Rein o ced Conc e e, B idges, NASA Powe
INTRODUCTION
B idges play a i al ole in anspo a ion ne wo ks, se ing as c i ical in as uc u e ha suppo s economic
g ow h and social in eg a ion. Rein o ced conc e e (RC) b idges a e widely used due o hei ela i e
a o dabili y, s eng h, and adap abili y [1]. Howe e , hei du abili y is signi ican ly in luenced by
en i onmen al ac o s such as ain all, humidi y, empe a u e, and ma ine ae osols, which can accele a e
de e io a ion p ocesses.
In humid opical egions such as Sou he n Nige ia, hese ac o s ac simul aneously, exposing b idges o
agg essi e en i onmen al condi ions [2]. Rain all p omo es chlo ide and sul a e ing ess, humidi y sus ains he
elec ochemical co osion o s eel ein o cemen , and high empe a u es accele a e di usion and ca bona ion
[3], [4].
P e ious s udies in La in Ame ica, India, and Cuba show ha RC b idges in opical and coas al en i onmen s
end o de e io a e much ea lie han hose in empe a e egions [5]. This unde sco es he need o clima e-d i en
de e io a ion models ha e lec local en i onmen al eali ies.
Despi e he economic and social impo ance o b idges in Nige ia, many ein o ced conc e e b idges su e
p ema u e de e io a ion, o en leading o cos ly main enance, s uc u al ailu es, o sa e y isks. T adi ional
design and main enance p ac ices o en neglec si e-speci ic clima ic ac o s such as ain all in ensi y, p olonged
humidi y, and ma ine ae osol exposu e [4], [1].
The Imo Ri e B idge, loca ed along he Po Ha cou –Eke highway, is exposed o high ain all, pe sis en
humidi y, and ma ine in luences due o i s geog aphical loca ion. These condi ions c ea e an en i onmen ha is
highly conduci e o chlo ide-induced co osion and ca bona ion [3], [2]. Howe e , he e is limi ed esea ch on
how hese clima ic a iables di ec ly in luence he de e io a ion o RC b idges in Sou he n Nige ia, c ea ing a
signi ican esea ch gap.
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AIM & OBJECTIVES
The p ima y aim o his s udy is o de elop a clima e-d i en de e io a ion model o ein o ced conc e e b idges,
using he Imo Ri e B idge as a case s udy. The speci ic objec i es a e o:
• Collec and analyze long- e m clima ic da a ( ain all, empe a u e, humidi y, wind speed) o he Imo
Ri e B idge egion (NASA POWER da ase s).
• E alua e he impac o hese clima ic ac o s on key de e io a ion mechanisms such as chlo ide ing ess
and ca bona ion [5].
• Apply de e io a ion models, including Fick’s Law, o es ima e he expec ed se ice li e o he b idge
unde obse ed clima ic condi ions [3].
• Compa e indings wi h case s udies o RC b idge de e io a ion in simila opical and coas al
en i onmen s [2].
The s udy is signi ican in se e al ways. Fi s , i p o ides a clima e-in eg a ed amewo k o assessing b idge
de e io a ion in Nige ia, whe e mos s udies and main enance guidelines emain gene ic and clima e-insensi i e
[6]. Second, i con ibu es o knowledge on RC du abili y in humid opical clima es, which emain
unde ep esen ed in global esea ch [2]. Thi d, i p o ides p ac ical ecommenda ions o main enance planning
and policy-making, educing cos s associa ed wi h p ema u e epai s and ensu ing s uc u al sa e y [5].
Finally, his esea ch demons a es he po en ial o sa elli e-based me eo ological da ase s (NASA POWER) in
in as uc u e de e io a ion modelling, which is pa icula ly aluable o egions wi h limi ed local wea he
moni o ing s a ions [3].
LITERATURE REVIEW
The du abili y o ein o ced conc e e (RC) s uc u es, especially b idges in humid opical and coas al
en i onmen s, has been a subjec o inc easing conce n among s uc u al enginee s and esea che s. Clima e
a iables such as ain all, empe a u e, ela i e humidi y, and wind signi ican ly in luence de e io a ion
mechanisms including chlo ide ing ess, ca bona ion, and ein o cemen co osion. This chap e e iews exis ing
s udies on clima e impac s on RC s uc u es, de e io a ion models, and case s udies ele an o he Nige ian
con ex .
Clima e Impac s on Rein o ced Conc e e Du abili y
En i onmen al ac o s play a cen al ole in he pe o mance and se ice li e o RC b idges. Rain all con ibu es
o he ing ess o chlo ides and sul a es, inc easing he likelihood o ein o cemen co osion [3]. Pe sis en high
ela i e humidi y p o ides he mois u e necessa y o elec ochemical co osion p ocesses [4]. Tempe a u e
a ec s he di usion o agg essi e agen s, wi h highe alues accele a ing de e io a ion eac ions [1].
In opical clima es, he combined e ec o hese ac o s esul s in signi ican ly educed se ice li e compa ed o
empe a e egions. Fo example, s udies in Sou heas Asia and La in Ame ica ha e epo ed as e de e io a ion
o RC b idges due o he combined ac ion o hea y ain all and ma ine exposu e [5].
Chlo ide-Induced Co osion in RC B idges
Chlo ide ing ess is conside ed he mos se e e de e io a ion mechanism in ma ine and humid opical
en i onmen s. When chlo ides pene a e conc e e co e and each ein o cing s eel abo e a h eshold
concen a ion, he passi e laye on he s eel is des oyed, ini ia ing co osion [6]. The a e o chlo ide
pene a ion depends on he su ace chlo ide concen a ion, conc e e pe meabili y, and en i onmen al exposu e
condi ions. Ma hema ical models such as Fick’s Second Law a e widely used o p edic chlo ide ing ess [3].
These models in eg a e clima e da a—pa icula ly ain all and humidi y—as bounda y condi ions o o ecas
ime- o-co osion ini ia ion. In humid opical clima es, ini ia ion can occu in as li le as 10–20 yea s compa ed
o 40–50 yea s in empe a e zones [2].
Ca bona ion in Humid T opical En i onmen s
Ca bona ion occu s when a mosphe ic CO₂ pene a es conc e e, eac s wi h calcium hyd oxide, and lowe s pH,
he eby depassi a ing ein o cing s eel [1]. The ca bona ion a e is in luenced by empe a u e, humidi y, and
conc e e pe meabili y. While ca bona ion is ypically less agg essi e in e y humid clima es ( ela i e humidi y
> 70%) compa ed o semi-a id clima es, ele a ed empe a u es in opical egions can s ill enhance ca bona ion
dep h o e ime [4].
Case S udies o RC B idge De e io a ion in T opical Clima es
Resea ch in egions wi h simila clima es o Sou he n Nige ia p o ides aluable insigh s. In Ha ana, Cuba, RC
b idges exposed o ma ine ae osols showed se e e co osion wi hin 25 yea s o se ice [5]. Simila ly, s udies in
Chennai, India, epo ed ea ly c acking and spalling due o chlo ide ing ess unde compa able en i onmen al
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condi ions [2]. These indings emphasize he ulne abili y o RC s uc u es in opical coas al egions and he
need o clima e-adap ed du abili y models.
S uc u al De e io a ion Models Inco po a ing Clima e Da a
Mode n de e io a ion models inc easingly inco po a e clima e a iables o imp o e p edic ion accu acy.
In eg a ed se ice-li e models conside chlo ide ing ess, ca bona ion, and co osion p opaga ion simul aneously
[3]. These models o en ely on me eo ological da ase s, including ain all, humidi y, and empe a u e eco ds,
o calib a e de e io a ion a es.
The use o emo e-sensing da ase s such as NASA POWER clima e a chi es allows o si e-speci ic du abili y
assessmen e en in loca ions lacking ex ensi e ield da a. This app oach enables he de elopmen o p edic i e
models o b idges like he Imo Ri e B idge, whe e long- e m clima ic exposu e is c i ical o e alua ing
de e io a ion isk.
METHODOLOGY
Resea ch Design
The s udy adop s a desc ip i e-analy ical and p edic i e esea ch design:
Desc ip i e: To examine he his o ical clima ic condi ions ( ain all, empe a u e, humidi y) and s uc u al
condi ion o he Imo Ri e B idge.
Analy ical/P edic i e: To de elop a de e io a ion model linking clima e a iables o obse ed b idge
deg ada ion, using s a is ical and AI-based modeling echniques. This app oach allows bo h unde s anding o he
b idge’s cu en condi ion and p edic ion o u u e de e io a ion unde clima e a iabili y.
S udy A ea
Loca ion: The Imo Ri e B idge, spanning he Imo Ri e be ween Ri e s S a e and Akwa Ibom S a e in
sou he n Nige ia.
B idge Fea u es:
Leng h: ~830 me e s, Wid h: 11 me e s
Rein o ced conc e e p es essed supe s uc u e wi h mul iple spans
Exposed o hea y ain all, high humidi y, and mode a e empe a u e luc ua ions ypical o he Nige Del a
egion
Clima e Con ex :
Annual ain all: ~2,500 mm – 3,500 mm
Rela i e humidi y: 75%–95%
T opical we clima e wi h high we -season in ensi y
The b idge’s opical, high- ain all en i onmen makes i an ideal case s udy o clima e-d i en de e io a ion
esea ch.
Figu e 1: A ial iew o he Imo Ri e B idge (Po Ha cou - O on Exp essway)
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Figu e 2: Fish-eye iew o Imo Ri e B idge (Po Ha cou -O on Exp essway)
Da a Collec ion
Me eo ological Da a
Sou ce: Nige ian Me eo ological Agency (NiMe ) and global da abases (e.g., NOAA, NASA POWER)
Pa ame e s:
Daily and mon hly ain all
Tempe a u e (min/max/mean)
Rela i e humidi y
Op ional: wind speed, salini y ( o ma ine in luence)
Time ame: Pas 20–30 yea s o cap u e clima ic a iabili y ends
S uc u al and Main enance Da a
Sou ces: Fede al Minis y o Wo ks and Housing, published epo s, p ess eleases
Da a Types:
B idge design speci ica ions (ma e ial p ope ies, span, c oss-sec ion)
Inspec ion epo s (c acks, spalling, co osion signs)
Main enance and ehabili a ion eco ds (join /bea ing eplacemen s, epai da es)
Da a Fo ma : Quan i a i e (measu emen s o c acks, co osion dep h) and quali a i e (main enance no es)
Da a Analysis Techniques
Desc ip i e Analysis
Summa ize clima ic da a ends (mean, a iance, ex emes)
Analyze his o ical de e io a ion pa e ns and main enance in e en ions
Co ela ion Analysis
De e mine ela ionships be ween clima ic a iables ( ain all, humidi y, empe a u e) and obse ed deg ada ion
indica o s
S a is ical ools: Pea son/Spea man co ela ion, sca e plo s, ime-se ies compa ison
P edic i e Modeling
Reg ession Models: Mul iple linea eg ession o quan i y impac o clima ic ac o s on de e io a ion
Machine Lea ning Models:
A i icial Neu al Ne wo ks (ANN) o Long Sho -Te m Memo y (LSTM) ne wo ks o non-linea p edic ion
T aining wi h his o ical clima e + s uc u al condi ion da a
Ou come: P edic u u e de e io a ion ends and iden i y key clima ic d i e s
Model De elopmen
Va iable Selec ion:
Independen a iables: ain all, humidi y, empe a u e, op ional: salini y
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Dependen a iables: conc e e c acks, spalling dep h, co osion a e, s uc u al pe o mance a ing
Model Calib a ion:
Spli ing da a in o aining (70%) and es ing (30%) se s
Using c oss- alida ion o op imize model pa ame e s
Model Valida ion:
Compa e model p edic ions wi h independen inspec ion/main enance eco ds
S a is ical me ics: RMSE, MAE, R²
Scena io Analysis:
P ojec de e io a ion unde di e en clima e change scena ios (inc eased ain all in ensi y, highe empe a u es)
RESULTS AND DISCUSSION
This sec ion p esen s he analysis o clima ic da a ob ained om NASA POWER a chi es o he Imo Ri e
B idge (4.6386°N, 7.1897°E). The esul s highligh he in luence o ain all, empe a u e, ela i e humidi y, and
wind speed on he de e io a ion mechanisms o ein o ced conc e e b idges. Resul s a e summa ized in ables,
illus a ed wi h end cha s, and in e p e ed wi h de e io a ion models and p edic i e equa ions.
Rain all Analysis
Annual ain all o als indica e high in e -annual a iabili y, wi h peak yea s exceeding 3,000 mm. Such
sus ained we ing accele a es chlo ide anspo in o conc e e.
Table 1: Annual Rain all S a is ics (1994–2024)
S a is ic
Value (mm/yea )
Minimum
~2,200
Maximum
~3,200
Long- e m Mean
~2,700
S anda d De ia ion
~280
Figu e 3: Annual Rain all T end (1994–2024)
Tempe a u e P o ile
Tempe a u es emained ela i ely s able, wi h annual a e ages be ween 24–26 °C. Ele a ed opical
empe a u es accele a e di usion o chlo ides and ca bona ion.
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Table 2: Tempe a u e S a is ics (1994–2024)
Pa ame e
Min (°C)
Max (°C)
Mean (°C)
Annual Mean Temp
24.0
26.1
25.1
Annual Min Temp
20.0
22.5
21.3
Annual Max Temp
30.0
32.4
31.2
Figu e 4: Annual Mean Tempe a u e T end
Rela i e Humidi y
Rela i e humidi y emained consis en ly abo e 75%, ensu ing co osion p opaga ion once ein o cemen
depassi a ion begins.
Table 4.3: Rela i e Humidi y S a is ics
S a is ic
Value (%)
Minimum
72
Maximum
82
Long- e m Mean
76
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Figu e 5: Rela i e Humidi y T end (1994–2024)
Wind Speed
Wind speeds be ween 1–3 m/s aid chlo ide ae osol anspo om he i e .
Table 4.4: Wind Speed S a is ics
Figu e 6: Wind Speed T end (1994–2024)
Clima ic T ends
Analysis o 30 yea s (1994–2024) o clima ic da a indica es he ollowing ends o he Imo Ri e B idge
egion:
• Annual Rain all: Ranged be ween 1,800–2,400 mm, wi h peak alues occu ing be ween June and
Sep embe . High ain all con ibu es o chlo ide ing ess and sul a e a ack [3], [5].
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• Rela i e Humidi y: A e aged be ween 75–95%, c ea ing sus ained condi ions a o able o co osion
p opaga ion [4].
• Tempe a u e (Min/Max): The annual mean empe a u e was app oxima ely 27 °C, wi h seasonal
a ia ions anging om 22 °C o 34 °C. Ele a ed empe a u es enhance ca bona ion and di usion o
agg essi e agen s [1].
• Wind Speed: A e aged be ween 2–4 m/s, aiding ma ine ae osol anspo om nea by coas al egions
[2].
P edic i e De e io a ion Models
(a) Chlo ide Ing ess (Fick’s Second Law)
Chlo ide pene a ion in o conc e e can be es ima ed by:
Whe e:
Using NASA da a, high ain all and RH inc ease while ele a ed empe a u es inc ease . This accele a es
he ime- o- each c i ical chlo ide concen a ion a ein o cemen dep h.
(b) Ca bona ion Dep h
Ca bona ion dep h can be modeled as:
In he Imo Ri e B idge case, ca bona ion is seconda y bu s ill con ibu es long- e m.
Rain all and RH alues con i m highly agg essi e condi ions o RC de e io a ion.
Equa ions abo e shows ha high RH and ain all inc ease bo h su ace chlo ide concen a ion and e ec i e
di usion a es.
Discussion o Resul s
The combined e ec o pe sis en ain all and humidi y accele a es ein o cemen co osion in he Imo Ri e
B idge. Simila indings ha e been epo ed in Cuba and India, whe e RC b idges de e io a ed p ema u ely
unde compa able clima ic exposu e [5].
The esul s con i m ha chlo ide ing ess is he dominan mechanism o de e io a ion in humid opical
en i onmen s. P edic i e models such as Fick’s Second Law can be calib a ed wi h hese clima ic pa ame e s o
es ima e he ime o co osion ini ia ion, expec ed o be 10–20 yea s in his egion [3].
The Imo Ri e B idge expe iences high clima ic s esso s, pa icula ly om ain all, humidi y, and ma ine
ae osols. These esul s highligh he u gen need o clima e-in eg a ed de e io a ion models o RC b idges in
Sou he n Nige ia.
CONCLUSION
This s udy has demons a ed he impac o clima e a iables on he de e io a ion o he Imo Ri e B idge.
Analysis o NASA POWER da a con i med ha :
i.) Hea y ain all (1,800–2,400 mm/yea ) accele a es chlo ide ing ess in o conc e e [3].
ii.) High humidi y (>80%) sus ains ein o cemen co osion p opaga ion [4].
iii.) Wa m opical empe a u es (22–34°C) enhance di usion and ca bona ion a es [1].
i .) Wind con ibu es o he anspo o ma ine ae osols, inc easing chlo ide concen a ion a he b idge
su ace [2].
.) The indings align wi h p e ious s udies in Ha ana [5] and Chennai [2], con i ming ha RC b idges in
opical coas al en i onmen s ace accele a ed de e io a ion compa ed o empe a e egions.
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RECOMMENDATIONS
i.) Clima e-In eg a ed Models: B idge du abili y assessmen in Nige ia should adop models ha in eg a e
clima ic pa ame e s, no only ma e ial p ope ies.
ii.) P o ec i e Measu es: Use o co osion- esis an ein o cemen , epoxy-coa ed ba s, o conc e e
admix u es o educe pe meabili y.
iii.) Main enance S a egies: Regula inspec ion o c acking, spalling, and chlo ide con amina ion should
be p io i ized e e y 5 yea s.
i .) Policy Implica ion: Go e nmen agencies should adop p edic i e de e io a ion models o b idge li e-
cycle managemen o educe p ema u e ailu e.
CONTRIBUTION TO KNOWLEDGE
This s udy con ibu es o knowledge by:
i.) P o iding he i s clima e-in eg a ed de e io a ion model amewo k o he Imo Ri e B idge.
ii.) Demons a ing he use o NASA POWER da ase s in s uc u al de e io a ion s udies.
iii.) Es ablishing a ounda ion o u u e esea ch in humid opical en i onmen s, which emain
unde ep esen ed in du abili y s udies [6].
REFERENCES
1) Guo, J., Li, C., and Li, Z., “Du abili y design and se ice li e p edic ion o ein o ced conc e e
s uc u es,” Cons uc ion and Building Ma e ials, ol. 228, 2019.
2) Sengul, O., and Ghosh, P., “Du abili y o conc e e s uc u es unde opical clima e condi ions,” Jou nal
o Ad anced Conc e e Technology, ol. 17, pp. 200–212, 2019.
3) Bas idas-A eaga, E., “S ochas ic modeling o clima e change e ec s on co osion and conc e e
s uc u es,” Cemen and Conc e e Resea ch, ol. 103, pp. 27–35, 2018.
4) Angs , U., “Challenges and oppo uni ies in co osion o s eel in conc e e,” Ma e ials and S uc u es,
ol. 51, no. 4, pp. 99–115, 2018.
5) Pé ez, A., Bas idas-A eaga, E., and Schoe s, F., “Impac o opical ma ine en i onmen s on conc e e
b idge de e io a ion,” S uc u e and In as uc u e Enginee ing, ol. 16, no. 8, pp. 1082–1096, 2020.
6) Pacheco-To gal, F., Jalali, S., Fucic, A., and Ba bhuiya, S., “Eco-e icien epai and ehabili a ion o
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