Research On The Behaviour Of Steel-Concrete Continuous Composite Beams Under Combined Bending Moment And Torque

Compared with simply supported composite beams and cantilever composite beams under vertical eccentric loads,there exists positive and negative bending moment and torque in the continuous composite beams at the same time,its stress state is more complicated than the first two ones.At present,the study on stress performance of composite beams in positive bending and torsion is more than others.This paper is based on natural science foundation of Hebei Province Study on the behavior of steel-concrete composite beams under combined negative bending moment and torque(E2014210038).The stress performance of two string-concrete continuous composite beams are tested and theoretically studied under eccentricity loads.The main work and conclusions are as follows:(1)In this paper,the ultimate bearing capacity,the sectional strain,sliding,crack width and spacing of the concrete slabs,of continuous composite beams are obtained by experiment,it was found that composite longitudinal strain along the direction of high beam accord with flat section assumption while the load within 0.8 Pu,cross section slip increases with the increase of load,concrete slab crack spacing is associated with transverse reinforcement spacing.(2)The finite element model under different parameters was established by using ANSYS software,and the force analysis of the whole process was conducted.In the elastic phase,the longitudinal strain of the steel beam bottom plate is distributed along the transverse section along the transverse section,and the position of the transverse baffle is linear.The torsional strain of the steel beam bottom plate has the opposite trend in the cross section and the middle support section,and has the mutation value in the position of the web,and the torsional strain of the cross-section of the transverse baffle is linearly distributed;The longitudinal slippage along the beam axis is influenced by the connection degree and torsion ratio parameters and is similar to the shear distribution diagram.(3)Under the joint action of continuous composite beams in bending and twisting,bending moment redistribution in the negative moment region increased with the increase of load and bending moment redistribution coefficient increases,the torque redistribution occur rarely in composite beams;(4)The positive and negative bending moment and torque moment area showed a similar correlation,its expression is slightly different,in general,limit little influence on the ultimate bending moment and torque limit bending moment of torque limit.