箱型空腹屋盖与传统屋盖的结构性能对比研究

Comparative Study on Structural Performance of Box-Type Hollow Roof and Traditional Roof

提出了一种新型空间结构———铝合金蜂窝板箱型空腹屋盖结构,它是由轻质高强的铝合金蜂窝板通过特种连接件拼接而成的五面体或六面体箱型空腹结构,它不仅具有张力结构“轻质高强”的特点,还吸收了刚性结构高强度、高刚度的优点。为了探究箱型空腹屋盖相对于传统屋盖的结构性能的优势,以铝合金蜂窝板箱型空腹屋盖的承载力试验为基础,研究了箱型空腹屋盖的力学性能,运用ANSYS软件建立了完全协调和耦合两种有限元分析模型,并且验证了有限元分析模型的有效性。对三向网格型单层网壳、正放四角锥双层网壳、无底板的五面体箱型空腹屋盖、有底板的六面体箱型空腹屋盖4种结构进行了力学性能分析,并且分析了其经济性。结果表明:铝合金蜂窝板箱型空腹屋盖的连接性能良好,具有较高的空间整体刚度。其极限承载力高达结构自重的11倍,稳定承载力约为自重的3.6倍,且结构在屈曲时的变形极小,挠跨比仅为1/800。耦合模型适用于箱型空腹屋盖结构的有限元分析,其在弹性阶段与试验较吻合,极限承载力仅比试验值高出15%,在考虑安全系数后可以作为结构承载力的设计值。在网壳结构的静力性能方面,有底板的箱型空腹结构的跨中挠度值和构件应力比均为四者中最小,表现出了较高的承载能力和抗变形能力。在控制跨中挠度值相近的情况下,杆系结构网壳的构件应力比普遍要大于板系结构,板系结构的空间传力更为合理。在网壳结构的经济性方面,对于同等尺寸的网壳,无底板箱型空腹网壳的结构自重最小,而三向网格型单层网壳的建筑空间最大。随着网壳平面尺寸的增大,结构平均重量都随之降低,建筑空间相差越来越大。在满足结构力学性能的前提下,综合考虑建筑空间和结构自重,箱型空腹结构可以获得相对较好的经济性。在网壳结构的动力性能方面,板片结构的频率一般要比同等条件下的杆系结构的频率大,板片结构具有轻质高强的特点,且其质量和刚度的分布较杆系结构更为合理。箱型空腹屋盖的力学性能及经济指标均比较优异,但有各自适用的跨度范围。无底板箱型空腹结构适用于20 m跨度以下的网壳,而有底板箱型空腹结构因其刚度更大可适用于20~30 m跨度的网壳。

In this paper,a new type of spatial structure-aluminum honeycomb plate box-type hollow roof structure is proposed.It is a pentahedral or hexahedral box-type hollow roof structure composed of lightweight and high strength aluminum honeycomb plates spliced by special connectors.It not only has the characteristics of tension structure of light weight and high strength,but also absorbs the advantages of high strength and high stiffness of rigid structure.In order to explore the advantages of the structural performance of the box-type hollow roof compared with the traditional roof,based on the bearing capacity test of the aluminum alloy honeycomb plate box-type hollow roof,the mechanical properties of the box-type hollow roof were studied.Two finite element analysis models,the complete coordination model and the coupling model,were established by ANSYS software,and the effectiveness of the finite element analysis model was verified.The mechanical properties of three-dimensional grid single-layer reticulated shell,orthogonal pyramid double-layer reticulated shell,pentahedral box type hollow roof without bottom plate and hexahedral box-type hollow roof with bottom plate were analyzed,and its economy was analyzed.The results show that the aluminum alloy honeycomb plate box-type hollow roof has good connection performance and high spatial overall stiffness.The ultimate bearing capacity is as high as 11 times of the self-weight of the structure,and the stable bearing capacity is about 3.6 times of the self-weight.The deformation of the structure during buckling is minimal,and the deflection-span ratio is only 1/800.The coupled model is suitable for the finite element analysis of box-type hollow roof structure.It is consistent with the test in the elastic stage,and its ultimate bearing capacity is only 15%higher than the test value.It can be used as the design value of structural bearing capacity after considering the safety factor.In terms of static performance of reticulated shell structure,the mid-span deflection value and component stress ratio of box-type hollow roof structure with bottom plate are the smallest among the four,showing high bearing capacity and deformation resistance.In the case of similar mid-span deflection values,the component stress ratio of latticed shell with bar system structure is generally greater than that of plate system structure,and the spatial force transmission of plate system structure is more reasonable.In terms of the economy of the reticulated shell structure,for the same size of the reticulated shell,the box-type hollow reticulated shell without bottom plate has the smallest structural weight,while the three-dimensional grid type single layer reticulated shell has the largest building space.With the increase of the shell plane size,the average weight of the structure decreases,and the difference in the building space is also increasing.On the premise of satisfying the mechanical performance of the structure,considering the building space and structural weight,the box-type hollow structure can obtain relatively good economy.In terms of the dynamic performance of reticulated shell structure,the frequency of plate structure is generally higher than that of bar structure under the same conditions.The plate structure has the characteristics of light weight and high strength,and its mass and stiffness distribution are more reasonable than that of bar structure.The mechanical properties and economic indexes of box-type hollow roof are excellent,but they have their own applicable span range.The box-type hollow structure without bottom plate is suitable for reticulated shells with span less than 20 m,and the box-type hollow structure with bottom plate is suitable for reticulated shells with span of 20-30 m because of its greater stiffness.