Experiment Study Of Steel-Concrete Composite Beam Bridge Crack Width And Control Technique

In recent several decade years, steel-concrete composite beam bridge has been popularly applied in City Bridge and freeway interchange engineering, and achieved remarkable technique economy benefit and society benefit. Because of the negative bending appears in the top flange of continuous composite beam, and the concrete slab cracking has induced the stiffness depressed; harmfulness gas and polluted water or other corrosive liquid will infiltrated through those cracks, aroused rusting of the rebar, stud and steel beam, reduced the durability of the bridges and enlarged maintenance the cost and difficulty of bridge. Therefore, the crack is a very important research subject.It's necessary to carry through more experimental study about the crack problem of the continuous composite beam bridge negative bending region, in order to perfected the design calculating content, reflected the stress characteristic, confirmed the major factors of influencing on crack width more accurately, and controlled the crack width in the reasonable range, promoting the composite beam structure's applying and developing in our country.Based on the results of theoretical analysis, finite element simulation and experimental research, the following conclusions are drawn:(1) It is feasible in theory through the theoretical analysis, and adopting the finite element software ABAQUS to stimulate the process of cracks generating and developing, and finding out the major factors of influencing on the crack width.(2) It is feasible in the design method based on the results of finite element analysis and forefather research findings, altering the design parameters, adopting factorial design method to design specimen can obtain more experimental results by lesser specimens.(3) Composite beam works all right as a whole body and cross section's deformation accords with the horizontal section assumption. Crack load is about percent 25 of limit load, the first crack will appeared near the mid-span section when reach this load.(4) The major factors of influencing on crack width and space include of rebar content, rebar amount and composing, stud space and height, concrete flange slab thickness and width.(5) Through altering the rebar composition, namely, adopting the smaller diameter deformed reinforcing bar can effective control the crack's development and distributing. Properly increasing the rebar content can preferable control the crack generating and developing in the other parameters are same.