Bi-axial Quasi-static Testing Research Of High Hollow Reinforced Concrete Piers Strengthened With Adhering Steel Plates

Steel-bonded reinforcement is an effective method to improve seismic performance ofexisting reinforced concrete pier columns, which has many advantanges,such as sturdyand durable,less effects on existing structures,convenient and fast construction,flexiblestrengthening manners,reasonable economy, so it has an extensive application prospect.While plenty of existing bridges need to be strengthened to enhance seismic performance,study on seismic performance of high reinforced concrete piers strengthened withadhering steel plates has important theoretical significance and practical engineeringvalue.The main work in this thesis are listed as follows:1. Nine scaled models of high hollow piers were designed and fabricated in the lab, inwhich some important parameters, such as different initial damage extent, steel platethickness, axial compression ratio, slenderness ratio,et al were considered.Themulti-dimensional seismic behavior of the scaled pier models before and afterstrengthening with adhering steel plates were explored using the bi-directionalquasi-static testing method. Several seismic indicators,such as load-displacement skeletoncurves and hysteretic curves, ductility,degradation of strength and rigidity,as well asenergy dissipation were investigated.2. The nonlinear behavior of reinforced concrete piers strengthened with adheringsteel plates under bi-directional cycle loading were simulated by OpenSees software, andthe results were compared with the testing ones.3. Based on the testing and the finite element analysis,the multi-dimensional skeletonmodel of load-displacement restoring force of piers strengthened with adhering steelplates in consideration of axial compression ratio and slenderness ratio were studied andextracted primarily.The main conclusions extracted from the testing and analysis are listed as follows:1. Under the interaction of axial load and bi-directional earthquake load, thereinforced concrete piers present typical fexural failure, and plastic hinge appears in thesuperior margin of steel, while it occurrs in the bottom of piers without strengthening.The seismic performance of reinforced concrete piers is effectively enhanced by adhering steel plates.2. The experimental results indicate that the initial damage extent only has very smalleffect on degradation of rigidity and energy dissipation of piers strengthened withadhering steel plates, and the seismic performance of piers strengthened with adheringsteel plates is insensitive to plate thickness varying from3to5mm. In the meanwhile, thechanges of axial compression ratio and slenderness ratio have a great impact on theseismic performance.The carrying capacity and energy dissipation of models will increasewith the increase of axial compression ratio.With the decrease of slenderness ratio, thecarrying capacity of piers strengthened with adhering steel plates will increase,while thedegradation of strength and rigidity become more serious.3. The constructed non-linear finite element model by using the finite elementsoftware OpenSees could reflect the seismic performance of high hollow reinforcedconcrete piers strengthened with adhering steel plates,the load-displacement skeletoncurves and hysteretic curves from the FE model simulation have a great agreement withthe experimental results.4. The bi-directional model of restoring force of piers strengthened with adhering steelplates considering axial compression ratio and slenderness ratio is proposed primarily inthis thesis, which can be referenced for further study on multidimensional restoring forcemodel of this kind of structure.