弦支式互承网格结构受力性能试验及有限元分析

Experimental study and finite element analysis on mechanical behavior of suspended reciprocal grid structures

互承网格结构是一种由杆件相互搭接所构成的空间结构,具有节点构造简单、安装快速、结构杆件与建筑表皮一体化等特点,但是存在结构刚度相对较小的问题。在不改变互承网格构形的前提下,为了改善其力学性能,提出了弦支式互承网格结构。该结构通过树状撑杆将上弦互承网格与下弦索相结合,实现协同工作。以跨度为4 m的弦支式互承网格结构模型为研究对象,通过静力加载试验验证了该结构可行性,并分析了其在试验荷载下的受力性能。通过有限元分析了实际尺度弦支式互承网格结构模型的受力性能,通过参数分析研究了矢跨比和预应力对结构的影响。研究结果表明:在试验荷载下,弦支式互承网格结构可以有效降低互承网格的位移与应力,测点位移降幅为30%以上,测量截面应力降幅为15%以上;在均布荷载作用下,弦支式互承网格结构的上弦杆件最大应力具有旋转对称性,结构稳定承载力高于常规互承网格结构,相同荷载下位移明显小于常规互承网格结构;弦支式互承网格结构最大位移随着矢跨比增大而减小,矢跨比过大时会导致树状撑杆长度较大,导致结构稳定承载力下降。

The reciprocal grid structures are a kind of spatial structures composed of mutually supporting bars.They have the characteristics of simple connections,quick construction and integration of structural skeleton with building skin.However,their structural stiffness is relatively small.The suspended reciprocal grid structures were proposed to improve the mechanical behavior of reciprocal grid structures without changing their topology.The structures integrated the reciprocal grid and cables by tree-like struts for composite actions.Taking a structural model with a span of 4 m as the object,the feasibility of the structures was verified and their mechanical behavior was demonstrated by a static loading test.The mechanical behavior of suspended reciprocal grid structures with an actual scale was studied by finite element analysis,and the influence of rise-span ratio and prestress on the structures was studied through parameter analysis.The research results show that the suspended reciprocal grid structure can reduce the displacement and stress of reciprocal grid.The displacement and stress of the gauging point decrease by more than 30%and 15%of general reciprocal grid structures,respectively.Under the uniform load,the maximum stress of the reciprocal grid has rotational symmetry.The stability capacity is higher while the displacement is much smaller than those of general reciprocal grid structures.The maximum displacement of suspended reciprocal grid structures decreases with the rise-span ratio.Excessive rise-span ratios lead to greater lengths of tree-like struts and the decrease of stability capacity.