Model Test Of Continuous Composite Box Girder In Hong Kong-Zhuhai-Macao Bridge

Steel and concrete composite continuous box structure has been widely used in the large span bridge structure because can make good use of concrete compression strength and steel tensile strength, which can make this composite structure have high bearing capacity, good plasticity and toughness, the speed of erection, remarkable economic effect. The HZMB shallow water non-navigable bridges, which use large segments of the entire hole lifting, change simply-supported beams into continuous system, lift up and down of the fulcrum, stretch-draw longitudinal pretesting of the fulcrum in the construction process, are composed of (6-7) x85m combination of continuous steel box girders.In order to research the force performance of bridge in the construction process and operation stage, the article combines the model test and the three dimensional space finite element analysis, designs a two-span composite continuous box girder (2×8.5m) test model, according to stress similarity as the index. The test model simulated the actual construction process of the bridge, applied the load according to25%、50%、75%、100%、125%、150%of normal operation load and established "concrete bridge panel-shear studs-steel box girder" finite element model of the test model to acquire the internal force and deformation characteristics under multi-stage operation load. The computed result provided the theory basis of the test data of the test model,In this article, there are main points about research content and conclusions:(1) Derived similar index when the similar constant is different at three different directions. The article introduced the similar theory of structural model when stress similarity is considered as the index. Then, the article derived similar index of three different proportion on the principle of the similar theory, taking structural geometry dimension material elastic modulus、stress form and other factors into consideration.(2) Designed and produced the test model. The article take the practical engineering (Hong Kong-ZhuHai-Macao bridge) as the background, simulated the bridge structural details and construction process precisely, designed a two-span composite continuous box girder (2x8.5m) test model, according to the similarity index which has been derived.(3) The simulation analysis of test model. The article used finite element analysis software (ANSYS) to simulate the construction process and operation stages of the designed test model (2x8.5m) and get stress characteristics of the theoretical value and the change rule of the test model under various working conditions. The computational data provided the theoretical basis for loading test.(4) Loading test of test model. The article tested the model beam under the various working conditions, verified the correctness of the model design and got stress and deformation characteristics of steel-concrete composite continuous box-girder.It turns out that the test model has simulated the actual construction process of the bridge precisely. The internal force and deformation characteristics can reflect the actual force characteristic of the bridge. The stress of the web of steel box girder is linear. At the same time, the stress of floor and wing of the steel box girder, concrete slab is less than the theoretical value. In the process, test model didn’t show any damage, which showed flexibility state and the overall excellent performance of the model. Fiber concrete can improve concrete’s crack resistance in the fulcrum negative moment region, comparing to the common concrete.