Experiment Study Of Composite Girder With Concrete In Tension

Composite girders can make good use of advantages of steel and concrete, so they are used extensively, and their structure forms have developed from early single simple-supported girders to continuous composite girders. Concrete slabs are in tension nearby the middle support of continuous composite girders. In the thesis, study has been made about the distribution and development of concrete slabs crack, calculation methods of crack width and measures for crack control, the ultimate bearing capacity of stud shear connectors when concrete slabs are in tension.Some concrete-steel composite girders have been made, then a two million times fatigue test and ultimate load capability test have been carried out. Under the condition of different fatigue times and different loads, the crack distribution has been observed, and space and width have been measured. Then the reasons of influencing crack distribution and width have been discussed.Analysis and comparison about several present influential crack theories and calculation methods of crack width have been made. Crack width calculation of many composite girders has been done with the formulas listed in different countries' codes or recommended by researchers. Then the comparison between calculation results and test results has been made. On this base, main reasons of influencing concrete slab's crack width of composite girder have been discussed.The importance of crack control to composite girder has been discussed, and agreat amount of data are collected. Then analysis and comparison about all kinds of control methods of crack, practicability advantages and disadvantages have been made which can provide reference to design and construction.A kind of test method-inverse push-out test is put forward. Test samples are separated into five groups according to different studs collocation and reinforcement content. The strength of studs and the slips between the concrete slabs and steel girders have been determined then the effect of different studs collocation and reinforcement content on the strength of studs has been analyzed.The research results have been applied to design and construction concerned.