Analysis Of Shear Behavior Of The Reinforced Concrete Beams With Partially Corrosion-damaged Length

At present, there are limited experimental research works on reinforced concrete(RC) elements with partially corrosion-damaged length. Research work, which isfocused on the shear behaviours of RC beams with corroded stirrups and longitudinalreinforcements within partial length located at one shear span, is also little. Moreover,the whole length of the longitudinal reinforcements was corroded in the most of theexisting research works. In experimental research, complete loss of bond within thepartial length was adopted and/or longitudinal tensile bars were exposed to study theshear performance of the RC beams with partially corrosion-damaged length. Itdiffers much from the actual situation and may lead to inappropriate or evenmisleading experimental conclusion. When those experimental conclusions were usedto analyze and predict the residual shear capacity of RC beams with partially corrodedlength, inappropriate or even misleading results may be obtained. In addition, only theinfluence of the corroded stirrups on the shear capacity was considered in theproposed shear capacity models of RC beams with partially corroded length, which isnot a typical one.In the present thesis, considering the adoption of the RC beam with partiallyunbonded length to study the shear performance of the RC beam with partiallycorroded length, shear behaviour of RC beams with partially unbonded length andpartially corroded length was studied, both experimentally and analytically. Thedifference of the shear behaviour between two types of the beams was obtained.Considering the influence of corroded stirrups and longitudinal reinforcementswithin partial length on the shear capacity of corrosion-damaged RC beams, shearcapacity models of the RC beams with partially corroded length within beam-spanand one shear span were proposed. The main work includes:1. For RC beams with partially unbonded length and partially corroded length at oneshear span, experimental study on the shear performance was carried out. For RCbeams with partially corroded length, both stirrups and longitudinal reinforcementwere corroded. Difference of the shear behaviour between the two types of thebeams was studied and the main parameters included:1) different lengths ofcomplete loss of bond at one shear span2) different lengths of corroded zone atone shear span3)different corrosion levels of the longitudinal reinforcements andstirrups within corroded lengths.2. For RC beams with partially unbonded length, typical experiments published inthe literature were selected and simulation analysis was carried out by finiteelement software, where the partially unbonded lengths in the beams were locatedat the middle beam-span and one shear span. By arranging combine element along the whole steel bars and making the zero bond strength in the partially unbondedlength, shear behavior of RC beams with partially unbonded length were analyzedand discussed.3. For RC beams with partially corroded length, typical experiments published in theliterature were selected and simulation analysis was carried out by finite elementsoftware, where the partially corroded lengths in the beams were located at themiddle beam-span and one shear span. Considering the mechanical property of thereinforcements at different corrosion levels within the corroded length, bondstrength between corrosion bars and concrete as well as the influence of corrosionexpansion on the cracking of the concrete cover, shear behavior of RC beams withpartially corroded length were analyzed and discussed.4. Basing on the experimental study on the shear performance of RC beams withpartially unbonded length and partially corroded length at one shear span, thefinite element analysis on the RC beams partially unbonded length and partiallycorroded length, shear performance of the two types of the beams were comparedand discussed.5. Assuming the shear strength of concrete beam is resisted primarily by thecompression zone of intact concrete, considering the interaction between the shearstrength and normal stresses developed by the flexural moment as well as theinfluence of corroded stirrups and longitudinal reinforcements within partiallength, shear capacity models of the RC beams with partially corroded lengthwithin beam-span and one shear span were proposed.In conclusion, in the present thesis, on the basis of the experimental study on theshear performance of RC beams with partially unbonded length and partially corrodedlength at one shear span, the finite element analysis on the RC beams partiallyunbonded length and partially corroded length located at the middle beam-span andone shear span, the different mechanical properties and shear performance of the twotypes of the beams was clarified. It can be conclude that the two types of the beamscan't substitute each other. For the purpose of the predicting of the residual strengthof existed corrosion-damaged RC beams, it is necessary to develop the shear capacitymodels of the RC beams with partially corroded length. Shear capacity models of theRC beams with partially corroded length were proposed by considering the influenceof corroded stirrups and longitudinal reinforcements within partial length.Comparison between shear strength predicted by the proposed method and the testresults showed good accuracy and the proposed strength model can be used to predictthe residual strength of existed corrosion-damaged RC beams.