Mechanics Property Analysis On Shear Capacity Of Steel-concrete Composite Beams Based On The HFWT System

Hybrid Full Web and Truss System(here in after referred to as HFWT in below) has the advantages of good structural integrity, global stiffness, reasonable force transformation mechanics, attractive appearance, etc. However, there are scarce relative experimental study and design theory, which restricts its wide extensive application. So it is necessary to take further research.This paper is to study the structure of HFWT by the technical route-“raise questions, simplified model, experimental verification, based on the analysis of the finite element model, get a useful calculating method ”, the main research and achievements of this paper are as follows:1. The structure of HFWT was analyzed with method of finite element analysis(FEA) and verified by tests. The results showed that calculation and testing well coincide, which proved the accuracy and reliability of the method of FEM. Based on this, the changes between the diagonal struts of HFWT under the external load were calculated. Results indicated that diagonal struts’ axial force change from press to pull alternate each other clearly in accordance with the location from pedestal to the loading point, delivering vertical force in loading points along diagonal struts to the pedestal.2. A series of HFWT FEM with concrete slab(including HFWT FEM without concrete slab) were carried out with vertical load on the symmetrical point along the span. The main parameters were shear span ratio, the angle between brace and chord?, the angle between chord and cross section ?, I-beams FEM and HFWT FEM without concrete slab were built also as comparison. The results showed that shear capacity of a HFWT beam increases with the reduction of shear span ratio, as well as the reduction of the angle between brace and chord?, while changing the angle between chord and cross section ? has little influence. Angle? and angle ? both has little impact on elastic stiffness of HFWT, effective widths as broad as the whole slab can be depended upon.3. Based on the analysis of above mentioned HFWT without concrete slab model, considering the influence of the bending moment to the shear, the steel beam shear span ratios? has been used to set up calculation formula for shearing capacity of truss. Through the analysis of HFWT FEM results, combine truss shear capacity formula and steel shear capacity formula, the concrete flange shear span ratioc? was also considered to build concrete slab shear capacity. In a summary, the theoretical formulas of calculation for ultimate shear strength of HFWT were set up accordingly.4. This paper deeply made research to the mechanism of HFWT, revising I-steel beam/HFWT beam without concrete slab/HFWT beam with concrete slab shear deformation correction coefficient k, and put forth the calculating formula of the deflection caused by shear deformation, which proved to work well compared with the results of FEA. The results indicated that the deflection considering shear deformation of simplified calculation formula can well predict the load-displacement response of the beam under external load in elastic stage. The achievement in this paper of such structure can be used in project design and for the design code reference.