Research On Static And Dynamic Response Of Steel Reinforced Concrete Bridge Piers

Steel reinforced concrete structure is a combined structure system in which we put section steel or skeletons of it inside the reinforced concrete. Comparing with common reinforced concrete structures, there is many advantages such as steel saving, better integrity, higher bearing capacity, better anti-seismic performance, more convenient construction and so on, Which make a brightening prospect of the application in building engineering and bridge engineering. And with the wider and wider application of section steel, it have led scholars and designers to widespread concerns and researches on its performance.With rapid development of Highway engineering in our country, the scale of bridge construction is increasing. No matter river bridges, sea bridges or cross line bridges, are all the bottlenecks of highway transportation system. But in recent years,accidents of motor vehicle-pier or vessel-pier collisions often occurred, causing serious damages or even collapses to the bridges, meanwhile, the researches on the design of dynamic strength of bridge piers are still rudimentary. In this work,2 reinforced concrete piers and 5 steel reinforced concrete piers (including 3 angle section steel concrete piers and 2 channel section concrete piers) are designed to study the performance of reinforced concrete piers under static concentrated load and impact loads, by the tests in which the piers were loaded under lateral concentrated loads and horizontal impact loads respectively. And the main contents and results of the research are as follows:1、The performances of the beams and the buffering devices are revealed by static and impact tests, in which the beams, buffers and beams with buffers on them were loaded under static loads and impact loads respectively. And relationships between the static and dynamic responses are also revealed based on the tests. Thus the reinforcement strain curves, stirrup strain curves, concrete strain curves and displacement curves of the beams and time-history curves of the compression of buffers are all concluded due to the results of tests.2、By analysis of the curves of beams in the tests concluded, responses of the beams under dynamic loads are obviously higher than that under static loads, which means the dynamic loads are non negligible factors when designing the strength of construction members. The energy absorption of buffers under dynamic loads are higher than that under static loads, which is told by the curves of the buffers under static-dynamic loads. After the energy absorbed by buffers are deducted, we compared the strains of the components with those under equivalent impact energy, and it is seen that the buffers are obviously influential on the properties of impact loads and dynamic responses of the components, which provide basic researches for follow-up studies on the certain relationships of static-dynamic response of piers and the influences of buffer devices on components under dynamic loads.3、By the contrast test of steel reinforced concrete bridge piers under static and dynamic loads, combined with analysis of the load-displacement curves under static loads, the performances of the piers are improved by section steels, also, the ultimate loads of the piers are improved, and the development of cracks are effectively inhibited; By the analysis of the load-displacement curves on reinforced strains under impact loads, buffers device significantly reduced the peak strain of reinforcements; Comparing the peak value strains under dynamic loads and the static stains in the experiment, the ratio obtained was rather discrete, which means the study of strain amplification factors is not a focus here.4、By using differential equations, combing the status of the displacements under static loads and dynamic loads respectively, the displacement response expression is acquired after taking the impact forces equivalent to step forces and triangle wave loads; And by comparing the static and dynamic responses, the expression of the calculation of the amplification factors of displacement were concluded, and the influence factors of displacements and amplification coefficients of displacements are analyzed, and the amplification coefficients of displacements on theory agree well with the actual test results, which provide basic researches for further studies on the design of dynamic strengths of bridge piers.