Experimental Study On Mechanical Behavior Of Composite Box-Girder With Corrugated Steel Webs

The externally prestressed composite box girder with corrugated steel webs is a new type steel-concrete composite structure. The steel webs bear the most of the shear force, and the top and bottom concrete slabs bear the moment of flexure chiefly. The particular advantages of each material can be utilized sufficiently, which reduce the quantities of substructures, so it will obtain extensive use in the future. Corrugated steel webs avoid the generation of skew cracks and, simultaneously, make difference on the mechanical performance between composite box-girder with corrugated steel webs and common steel-concrete composite beam.In this thesis, a series of load tests on two composite box girders with steel webs are conducted, including loading efficiency of external prestress, normal stress along the beam depth, load-deflection feature, and preliminary shear lag effect. Meanwhile, on the basis of long term in-door test, the creep performance of the test beam is obtained. The main work is described as follows:1. This thesis introduces the development, research and application actuality inland and abroad of composite box-girder with corrugated steel webs, summarizes the basic construction and forcing characteristic.2. Considering the contribution to the deflection of shearing deformation, based on the energy principle, the formula of the deflection is deduced, which is suitable for arbitrary load mode and section. Through the experimental research and FEM analysis, the formula is proved to be valid and accurate.3. The strain in the course of stretching prestressing tendons are observed. The characteristic of loading efficiency is obtained. Parametric studies are conducted to examine the effects of the type and thickness of the webs. The results indicate that the composite box girder with corrugated steel webs dominate over the aspect of the loading efficiency due to prestressing.4. Through the load test at the elastic stage, normal stress along the beam depth and preliminary shear lag effect are obtained. The comparisons of the FEM results adopting common structure analyses procedure Ansys and the test results are satisfactory.5. 205-day creep observation has been carried out. The results of the theoretical analysis, finite element analysis and data of experiments are accordant. Parametric study results adopting bridge analyses procedure Midas-Civil show that the inverted camber of composite box girder with corrugated steel webs is less than it of the common concrete beam in the condition of the same stress gradient.