REHABILITATION OF THE CONCRETE BRIDGE ACROSS HIGHWAY

Transcription

1 REHABILITATION OF THE CONCRETE BRIDGE ACROSS HIGHWAY Darko Meštrović*, Dean Čizmar* & Angela Nižić** *Faculty of Civil Engineering Univerity of Zagreb ** Lehrtull fuer Maivbau Techniche Univeritaet Muenchen Key word: concrete bridge rehabilitaion, FRP ytem Abtract: The need for rehabilitation of reinforced concrete tructure i raidly increaing. Until now, for rehabilitation wa ued teel that wa glued on concrete urface. Thi technology i now abandoned. Product of fiber reinforced olymer (FRP) are being ued intead. FRP ytem i integrated ytem baed on carbon fiber and eoxy reign. Strengthening i achieved a for comoite element, gluing lame on tructural element. In aer i reented integrated concet of rehabilitation of concrete bridge with an x meter. Bearing tructure i comoed (tranverally) of 5 beam with hollow oening. Beam are retreed adheively and additional tranverally on ite. Concrete ued i MB40, retreed with cable 12.4 mm and additionally reinforced with reinforced teel. Column are made of concrete MB35. Identification of tructure damage and the exloration activitie are exlained. Characteritic of FRP ytem are reented. The rooal for bridge rehabilitation i hown. Paer how that FPR ytem can be ued for rehabilitation and trengthening of concrete and retreed tructure. It can alo be ued for metal and wooden tructure

2 1. INTRODUCTION Fiber Reinforced Polymer (FRP) in civil engineering i ued for both tatic and eimic rehabilitation of tructure. FRP ytem i integrated ytem baed on carbon fiber and eoxy reign. Strengthening i achieved a for comoite element, gluing lame on tructural element. FRP i lightweight material o it i oible to ue le reource without the need for ecial machine. It i ued for rehabilitation of tructure due to earthquake, fire, imact and traffic load. 2. DESCRIPTION OF THE BRIDGE Bridge i made in 1980 and contructed a recat tructure. It ha 4 an ( x meter). Total length of the bridge i meter. Beam VIADUKT «SAN 210/75» tye are retreed in factory each with 48 roe ø12.4 mm and tranverally on ite. Concrete i MB 40, retreed with cable ø12.4 and additionally reinforced. Longitudinally beam are connected with cement mortar. Beam are laying on three air of column. Concrete ued for column i MB 35. Road lab i 7.7 wide. Figure 1 i the hotograhy of the bridge. U1 S1 S2 S3 U2 Figure 1: Photograhy of the bridge 3. EXPLORATORY WORKS Following exloratory work are conducted: viual inection, damage and crack identification, concrete amle acquiition and laboratory teting. Figure 2 i damaged abutment U1. Figure 3 i the head beam on column S1. Figure 4 dilay damage of column S1. Figure 5 i the bearing tructure between column S1 and S2. Concrete tructure i damaged rimary due to three imact. Firt i mechanical damage to tructure (rimary traffic). Second i imact of carbon dioxide from atmohere. Third and mot devatating i imact from reciitation water. Thee water interact with lat on road and detroy the concrete tructure. Mot devatating effect i chloride enetration to reinforcement that caued chloride corroion. Thee effect are viible on reinforcement. Due to corroion, the cro ection i aroximately 60% thinner. Pretreed roe have 20% thinner cro ection

3 Figure 2: Abutment U1 Figure 3: Head beam of column S

4 Figure 4: Column S1 Figure 5: Bearing tructure between column S1 and S

5 4. FRP SYSTEM FRP i new ytem that i rimarily ued for rehabilitation of concrete, retreed concrete, teel and wooden tructure. It i a comoite material, which mean that it i comoed from everal different material. Final roduct i material which ha extraordinary mechanical roertie. It ha high tenile trength and tiffne. It i 5 time lighter than concrete and 10 time tronger. Figure 6 how comarion of tre-train diagram of concrete, teel and FRP. FRP can be ued for rehabilitation of tructure becaue it i very eay to ue, cheaer. Due to very light material it not neceary to have ecial machine to be ued for rehabilitation. It can be ued for: rehabilitation of tructure that had crack and damage from earthquake, fire, exloion, reinforcement corroion, trengthening of tructural art etc. Figure 2: Examle of the contruction of one figure Strain Strain Stre Stre Stre Strain Figure 6: Stre- train diagram for concrete, teel and FPR material 5. CALCULATION AND STATIC CHECK Viual inection howed that bearing tructure i very damaged (due to corroion of reinforced and retreed roe). For an between column S1 and S2 tatic and tability check i made. It i concluded that retreed roe have 20% decreaed force. When

6 dimenioning FRP inut arameter are dimenion of the beam that will be rehabilitated, tenile and comreion reinforcement and the tye of concrete/teel. Dimenion and mechanical arameter of lamina and glue are given by manufacturer. Thi examle will how calculation of rectangular beam with one an. Center of gravity (d 1 ) i defined a in equation 1. d 1 = A d ( 1 + h ) + A A + A 0,5h (1) M Sd = M Rd M = γ M + γ M + Σγ M d Sd Rd = h g G c + h G d Q 1 Q = F z = ( F + F ) z Q Ψ O, i Q ki (2) (3) In Equation 2 and 3 M d i deign moment and M rd tand for reitance moment. Equation 4 give dimenionle arameter µ d. Looking in ref 4. dimenionle arameter i determined and equation 5 give neceary area of FRP. Other mark are hown in figure 7. µ A A A f f Sd cd yd = b g M d M = ς d Sd 2 Sd f /1,5 /1,15 f yd cd A = A E γ /( E γ ) = h = h = f = f b ck yk b (4) (5) (6)

7 Figure 7: Stre-train diagram 6. REHABILITATION OF THE BRIDGE Damaged concrete mut be removed by hydro demolition. Thi rocedure i ued for carbonized rotective layer. After thi area that will be rehabilitated mut be cleaned with water under high reure. After cleaning the area mut be rotected with high alkali that will to corroion roce. Than the ecial mortar i alied in 3 cm thick layer. Finih work i done in 2 te (firt with two-comonent mortar and econd te i rounding off the corner where FRP will be glued. Figure 8 how damaged beam of the bridge. Figure 9 how rehabilitated beam. Figure 8: Damaged beam

8 Figure 9: Rehabilitated beam 7. CONCLUSION Thi article rereent the oibility of rehabilitation concrete bridge by uing FRP. Uing thi high quality comoite material in rehabilitation and trengthening of tructure i very eay and work can be done quickly. FRP i lightweight material, o it i oible to ue fewer reource without the need for ecial machine. It mut be noted that during rehabilitation, in many ituation, tructure can be utilized normally. FRP ha a wide coe of alication: from rehabilitation of damaged tructural element a a reult of earthquake, fire, exloion and corroion. It can be alo ued for trengthening old tructure that have increaed action (traffic load etc). REFERENCES [1] Tomičić, I Strengthening of concrete beam with fiber reinforced olymer. Road and Bridge, Croatian Road: Zagreb. [2] Lam, D., Predicting failure for teel beam trengthened with carbon fibre reinforced olymer laminate.. 9 th Conference on Inection, Araial, Reair & Maintenance of Structure. Fuzhou, China. [3] Zgrablić, P., Rehabilitation of recat concrete bridge (B.Sc. degree thei.. Zagreb [4] Radić, J., Concrete tructure: manual. Zagreb: Croatian Univerity Pre. [5] Radić, J., Pontifex Maximu: life and work of greatet Croatian bridge deigner: rof. Krune Tonkovića. Zagreb: Dom i vijet