群钉连接装配式组合轨道梁受力特性研究

为促进钢-混凝土组合结构的工业化建造,实现钢构件和混凝土构件的工厂化预制、装配化施工,针对传统剪力钉均匀满铺建立的等效刚度理论不能反映群钉集中布置时组合结构受力特性的问题,以跨座式单轨交通为研究背景,设计制作群钉连接装配式钢-混凝土组合轨道梁,进行装配前的钢梁与装配后的组合梁固有频率、荷载-挠度曲线、截面应变曲线对比分析,研究群钉连接组合梁的受力特征。结果表明:钢梁、组合梁实测竖弯固有频率分别为29.9和32.2 Hz,混凝土板的叠合使组合梁固有频率较钢梁提高8%;组合梁内同一截面高度的钢梁和混凝土板变形不协调,混凝土板应变显著大于钢梁,是钢梁的2.5~2.8倍,不满足平截面假定;组合梁实测等效竖弯刚度随作用荷载变化呈非线性特征,简支边界条件下,实测等效竖弯刚度为理论值的0.9~1.1倍,跨中集中荷载小于500 kN时实测等效竖弯刚度大于理论值,而大于500 kN时实测等效竖弯刚度小于理论值。

Investigation of Mechanical Characteristics for Assembled Composite Track Beam Connected by Group Studs

In order to promote the industrial construction of steel-concrete composite structures and realize the factory prefabrication and assembly construction of steel and concrete members,aiming at problem that the equivalent stiffness theory established by the traditional uniform and full laying of shear studs cannot reflect the mechanical characteristics of composite structures when the group studs are arranged in a centralized way,an experimental steel-concrete composite track beam prefabricated with group studs is designed and manufactured according to straddle type monorail transit.The natural frequencies,load-deflection curves and section strain curves of the steel beam before assembly and composite beam after assembly are comparatively analyzed,and the mechanical characteristics of the composite beam connected by group studs are studied.Results show that the measured vertical bending natural frequencies of steel beam and composite beam are 29.9 Hz and 32.2 Hz respectively,and the natural frequency of composite beam is 8%higher than that of steel beam due to the superposition of concrete slab.The deformation of steel beam and concrete slab at the same section height in composite beam is not coordinated,and the strain of concrete slab is obviously larger than that of steel beam with a factor of 2.5—2.8 times,which does not meet the plane section assumption.The measured equivalent vertical bending stiffness of composite beam is nonlinear with the change of applied loads.The measured equivalent vertical bending stiffness under simply supported boundary condition is 0.9—1.1 times of the theoretical value.When the concentrated load at the middle of the experimental beam is less than 500 kN,the measured equivalent vertical bending stiffness is greater than the theoretical value and less than the theoretical value when it is greater than 500 kN.