钢结构交错桁架体系的高等分析

发布时间：2019-02-13 04:27

【摘要】：交错桁架结构体系是钢结构中的一种新型承重结构体系,国内外对钢结构交错桁架体系的结构布置、经济性能、受力特点、楼板和钢桁架共同作用、上下部结构共同作用、结构静力和动力弹塑性分析、结构静力弹性实验、静力和动力简化计算方法、柱子计算长度、节点构造等方面进行了研究,也已建成了许多交错桁架结构体系的建筑,但至今还没有人对钢结构交错桁架体系的高等分析方法进行研究。本文结合国家自然科学基金(50808096)资助项目,首次对钢结构交错桁架体系的高等分析方法进行了研究,旨在满足结构设计的需要,推动钢结构交错桁架结构体系的尽快发展,填补国内外在钢结构交错桁架结构体系的高等分析研究方面的空白。本论文主要完成了以下工作：首先,根据连续介质力学理论构造出钢结构交错桁架体系空间单元的几何刚度矩阵和弹塑性刚度矩阵,算例分析表明这些矩阵能准确地计算出结构的空间二阶效应和空间单元弹塑性杆端力增量,计算结果具有良好的精度。其次,通过对交错桁架结构的一些算例对比,首次提出了支撑交错桁架结构这一新型交错桁架结构体系,该体系很好的解决了传统交错桁架体系侧向刚度较弱的问题。再次,为方便工程设计,本文首次提出了能同时考虑二阶效应、几何缺陷、构件截面的塑性发展和残余应力的交错桁架结构体系的简化设计方法,该方法的优点是利用基于精细塑性铰方法修改后的单元刚度矩阵,比较准确的计算钢结构交错桁架体系的内力和稳定承载力,该方法具有较强的可操作性。通过对交错桁架结构体系工作性能的研究,可以得出如下结论： 1.交错桁架体系的纵向刚度明显弱于横向刚度,要保证纵向刚度满足规范要求,宜设置支撑体系来增加结构纵向刚度,改善结构在两个主轴方向刚度相差较大的现象； 2.纵向支撑的布置能明显减小楼层位移和层间位移角,有效提高纵向抗侧刚度,从而提高结构的抗震和抗风性能； 3.人字形支撑相比较于十字形支撑、V形支撑来说,适用性、经济性更好; 4.交错桁架结构中大部分构件能均处于轴心受力的状态,可充分地发挥材料的性能,降低结构的自重,从而达到节约材料,降低结构造价的目的。 5.交错桁架结构体系的最大层间位移角都发生在底部几层,因此,设计交错桁架结构体系时,应加强底部几层的设计。 6.结构的高宽比变化对结构的二阶效应和极限承载力的有较大的影响。当高宽比增大时结构的二阶效应增大,极限承载力减小。
[Abstract]:Staggered truss structure system is a new type of load-bearing structure system in steel structure. The static and dynamic elastoplastic analysis, the static elastic experiment, the simplified calculation method of static and dynamic force, the calculation length of columns and the structure of joints have been studied, and many buildings of staggered truss structure have been built. But up to now, no one has studied the advanced analysis method of staggered truss system of steel structure. In this paper, based on the project supported by the National Natural Science Foundation (50808096), the advanced analysis method of staggered truss system of steel structure is studied for the first time in order to meet the needs of structural design and promote the development of staggered truss structure system of steel structure as soon as possible. Fill in the gap in the advanced analysis and research of steel staggered truss structure system at home and abroad. The main work of this thesis is as follows: firstly, the geometric stiffness matrix and elastic-plastic stiffness matrix of spatial element of steel staggered truss system are constructed according to continuum mechanics theory. The numerical examples show that these matrices can accurately calculate the spatial second order effect of the structure and the end force increment of the elastic-plastic bar of the spatial element, and the calculation results have good accuracy. Secondly, through the comparison of some examples of staggered truss structure, a new type of staggered truss structure system is proposed for the first time, which solves the problem of weak lateral stiffness of traditional staggered truss system. Thirdly, in order to facilitate engineering design, a simplified design method of staggered truss structure system is proposed, which can take into account the second order effect, geometric defect, plastic development of member section and residual stress for the first time. The advantage of this method is that the internal force and stable bearing capacity of steel structure staggered truss system can be calculated accurately by using the modified element stiffness matrix based on the fine plastic hinge method. This method has strong maneuverability. Through the study of the performance of staggered truss structure system, the following conclusions can be drawn: 1. The longitudinal stiffness of staggered truss system is obviously weaker than that of transverse stiffness. In order to ensure that the longitudinal stiffness meets the requirements of the code, bracing system should be set up to increase the longitudinal stiffness of the structure, and to improve the phenomenon that the stiffness difference between the two main axes is large; 2. The arrangement of longitudinal bracing can obviously reduce the displacement angle between floor and floor, effectively improve the longitudinal lateral stiffness, thus improve the seismic and wind-resistant performance of the structure. 3. The herringbone bracing is more suitable and economical than the cross bracing and the V-shaped bracing. 4. Most of the members in staggered truss structure are in the state of axial force, which can give full play to the performance of material, reduce the weight of structure, and achieve the purpose of saving material and reducing the cost of structure. 5. The maximum interstory displacement angle of staggered truss structure system occurs in the bottom layers, so the design of the bottom layers should be strengthened when designing the staggered truss structure system. 6. The aspect ratio of the structure has great influence on the second order effect and ultimate bearing capacity of the structure. When the aspect ratio increases, the second order effect increases and the ultimate bearing capacity decreases.
【学位授予单位】：兰州大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU391

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