Mechanical Performance Analysis Of UHPC Composite Box Girder Bridge With Corrugated Steel Webs

As a relatively novel material,whether UHPC can play its advantages in the box structure with corrugated steel webs,whether the UHPC composite box girder bridge with corrugated steel webs can meet the requirements of the current specifications,and what are the advantages compared with the traditional corrugated steel webs composite box girder bridge is the first step in the feasibility study of its first use in practical engineering.The great difference of mechanical properties between UHPC and ordinary concrete has become the key to affect the mechanical behavior of corrugated steel web slab bridge.On the one hand,the high strength of UHPC can be used to reduce the section size;On the other hand,it can reduce the cost and economic benefit of HPC.In this paper,the corrugated steel web composite box girder bridge with UHPC as the top and bottom plate is compared with the traditional corrugated steel web composite box girder bridge.The main research contents and conclusions are as follows:(1)A traditional corrugated steel web composite box girder bridge with a main span of30 m is taken as the prototype.Compared with the UHPC corrugated steel web composite box girder bridge with the top and bottom section area reduced by 43%.The space calculation model was established by finite element software,and the strength,stiffness,stability and force calculation of connecting parts were checked according to relevant specifications.The results show that the UHPC composite box girder bridge with corrugated steel webs is feasible,which satisfies the requirements of structural mechanical performance and still has great redundancy.(2)Compared with the traditional composite box girder bridge with corrugated steel webs,the self weight of UHPC composite box girder bridge with corrugated steel webs can be reduced by about 28%;Considering the long-term effect,the live load deflection can be reduced by 53%;The ultimate state bearing capacity can be increased by 11% ～ 38%;After properly optimizing the connectors,the number of connectors can be greatly reduced.(3)After the section size is reduced,the stress of UHPC top and bottom plate is generally about 80% higher than that of the top and bottom plate in the traditional corrugated steel web,but the UHPC strength is about 3-5 times that of ordinary concrete,so there is still great redundancy for UHPC top and bottom plate.(4)Compared with the traditional composite box girder bridge with corrugated steel webs,the shear lag effect of the top and bottom slab of UHPC composite box girder bridge with corrugated steel webs is different under different loads.In general,the shear lag effect of UHPC top and bottom slab will be greater than that of ordinary concrete top and bottom slab.(5)The use of UHPC or ordinary concrete top and bottom plate has little mechanical impact on the corrugated steel web.Under the same load,the von Miese stress of the corrugated steel web is very different only at the connection between the corrugated steel web and the top plate,and the rest parts are almost the same;It has little effect on the buckling behavior of corrugated steel webs.(6)By comparing the first 20 modes,come to the conclusion that the natural vibration frequencies of UHPC composite box girder bridge with corrugated steel webs are higher than those of traditional composite box girder bridge with corrugated steel webs.(7)Through the contact analysis between the stud connector in UHPC roof and the stud connector in ordinary concrete,come to the conclusion that the deformation and stress of the stud in UHPC can be greatly improved,and the concentrated stress in UHPC roof can be rapidly diffused in a smaller range.