装配式弦支钢-混凝土组合楼盖中槽型板单元力学性能有限元研究

Finite Element Study on Mechanical Properties of Groove Plate Unit in Assembled Cable Supported Steel-Concrete Composite Floor

装配式弦支钢-混凝土组合楼盖是一种新型大跨度预应力组合结构,为了探究该组合楼盖中楼板部分的力学性能,从装配式弦支钢-混凝土组合楼盖中选取由4块槽型叠合板通过板间连接件连接组合形成的标准楼板单元,以此为研究对象,对其在正常使用阶段的受力性能进行有限元模拟分析。模拟结果显示,该组合楼板单元由于肋梁及后浇带的存在,在加载初期,单块槽型叠合板单元率先发生双向弯曲变形且跨中挠度最大,随着荷载的不断增加,组合楼板单元发生整体弯曲变形,跨中位置的挠度变形最大,当加载结束时,跨中挠度值为59 mm。在外荷载作用下,组合楼板单元沿跨度方向混凝土出现明显的塑性损伤,这表明两端简支组合楼板单元整体的抗弯刚度与垂直于跨度方向的截面有关。为详细探究混凝土强度、叠合层厚度、肋梁高度以及板间连接件的高度等参数对组合楼板抗弯刚度等力学性能的影响,建立13个有限元模型,对槽型钢筋桁架叠合板及板间连接件进行变参数分析,通过对比相同荷载与边界条件作用下跨中荷载-位移曲线,探究了不同因素对组合楼板抗弯性能的影响。结果表明:在保持其他条件不变的情况下,随着肋梁高度的增加,抗弯刚度急剧增大而位移迅速减小,肋梁高度从400 mm增大到700 mm,抗弯刚度增加322.6%,位移减小99%;随着叠合层厚度的增加,抗弯刚度增大而跨中位移减小,叠合层厚度从40 mm增大到70 mm时,抗弯刚度增加24.2%,位移减小54.7%;随着混凝土强度等级的增加,抗弯刚度略有增加而跨中位移未见明显变化,混凝土强度等级从C25增大到C40,抗弯刚度最大增加10.1%,位移在55~60 mm间波动;仅改变板间连接件高度并不改变其中心作用位置时,对抗弯刚度及位移影响不大,板间连接件高度从300 mm增大到360 mm,抗弯刚度增加8.0%,位移减小未超过10%。综上,对组合楼板整体的抗弯刚度及跨中位移影响最大的是肋梁高度,其次是叠合层厚度,混凝土强度及板间连接件高度影响较小。

Assembled cable supported steel-concrete composite floor is a new type of long-span prestressed composite structure.In order to explore the mechanical properties of the floor part of the composite floor,the standard floor element formed by the connection and combination of four slot laminated plates through inter plate connectors was selected from assembled cable supported steel-concrete composite floor.Taking this as the research object,the mechanical performance of it in the normal use stage was simulated and analyzed by finite element method.The simulation results show that due to the existence of rib beam and post cast strip,in the initial stage of loading,the single slot composite plate element takes the lead in two-way bending deformation,and the mid span deflection is the largest.With the continuous increase of load,the overall bending deformation of composite floor unit occurs,and the deflection deformation at the middle of the span is the largest.When the loading is completed,the deflection value at the middle of the span is 59 mm.Under the action of external load,the concrete of composite slab element appears obvious plastic damage along the span direction,which indicates that the bending stiffness of simply supported composite slab element at both ends is related to the section perpendicular to the span direction.In order to explore in detail the effects of concrete strength,thickness of composite layer,height of rib beam and height of connectors between plates on the flexural stiffness and other mechanical properties of composite floor slab,thirteen finite element models were established to analyze the variable parameters of the laminated plate and the connection between plates of the grooved reinforced truss.By comparing the mid-span load-displacement curves under the same load and boundary conditions,the effects of different factors on the flexural performance of composite floors were explored.The results show that when other conditions remain unchanged,with the increase of the height of the rib beam,the flexural stiffness increases sharply and the displacement decreases rapidly.The height of the rib beam increases from 400 mm to 700 mm,the flexural stiffness increases by 322.6%and the displacement decreases by 99%.As the thickness of composite layer increases,the bending stiffness increases and the midspan displacement decreases.When the thickness of composite layer increases from 40 mm to 70 mm,the bending stiffness increases by 24.2%and the displacement decreases by 54.7%.With the increase of concrete strength,the bending stiffness increases slightly but the midspan displacement has no obvious change.When the concrete strength increases from C25 to C40,the bending stiffness increases by 10.1%and the displacement fluctuates between 55 mm and 60 mm.Only changing the height of the inter-plate connector does not change its central position which has little effect on the bending stiffness and deflection.When the height of the inter-plate connector increases from 300 mm to 360 mm,the bending stiffness increases by 8.0%and the displacement decreases by less than 10%.In summary,the rib beam height has the greatest impact on the overall bending stiffness and mid-span displacement of the composite slab,followed by the thickness of the composite layer,and the concrete strength and the height of the connection between the slabs have little impact.