Analysis On Mutual Work Behaviors Of Composite Beams & Experimental Study On Concrete Slab Strengthened With Girder Steel

With the steady development of our society and the rapid increase in our economy, the innovative research about engineering and the durative development of application have been a growing concern among the general public. This development current must be paid much attention to in the field of maintenance and reinforcement in civil engineering. Therefore, how to make use of the current resources to the most effective degree for technical innovation together with searching the technique of maintenance and reinforcement is a research focus all over the world. Composite beams with its excellencies can be well applied in reinforcement engineering. How to make full use of the research results of composite beams in reinforcement engineering has become an issue of great significance.Simulated tests for 170 composite beams and 20 space composite beams are accomplished by the finite element method (FEM) program to the effect of the change of composite beams together work behavior with the change of the connect behavior. Deflection and flexural capability of composite beams with different connect degrees are also studied with the change of parameter of composite beams,such as nail collocation, concrete strength, length of concrete slab, width of concrete flange, dimension of steel beam, and load state. The finite element analysis serves as a reference for the following experimental design.The behaviors of the composite beams made form concrete slab with reinforcement of girder steel on its bottom, including failure modes, load-deflection curves, load-strain curves, and load-slip curves, the distribution of strain along the height direction and along the length direction of beams are tested from the static test of 4 simply supported specimens which have different connect methods and extents. The conclusion is that the failure modes of these composite beams are similar to the traditional composite beams, and load-deflection curves can be measured off into three stages: elastic stage, weak nonlinear stage, and plasticity stage. Composite beams can be well applied in reinforcement engineering with the improvement in its theory formula.Three states, which are no mutual work, part mutual work and full mutual work of the composite beams are studied in this paper. Deflection of composite beams are calculated by elaxtic rigidity method, improvement elaxtic rigidity method, semiempirical formula method, and mechanics of materials method. Flexural capability of composite beams are calculated by limit equilibrium method and semiempirical formula method. From these results,together with the significant comparison with the finite element analysis and the tests in this paper, deflection calculation formulae and flexural capability calculation formulae of composite beams are thereby deduced for the application in reinforcement engineering in this paper. Finally, Slip behaviors are studied elementarily and empirical formula of slip are deduced by statistics software.