【作者】 宋扬；

【导师】 丁阳；

【作者基本信息】 天津大学 ， 结构工程， 2007， 硕士

【摘要】 本文结合张弦桁架及桥梁工程的特点,将张弦桁架作为主要承重结构应用于一人行天桥的上部结构中,对该人行天桥结构进行以下五方面的计算分析。(1)对人行天桥结构进行静力荷载作用下的设计分析,初步确定结构构件的截面形式和规格,考虑张弦桁架的变形、构件的受力以及天桥的施工过程,确定拉索的初始张拉力值。桥面系的吊杆与张弦桁架下弦直接相连,吊杆与拉索位于同一平面内,为避免其相互接触影响结构受力设计了吊杆、拉索交汇处的特殊节点,同时对拉索的锚固节点进行承载力计算分析。(2)人群荷载激励下的天桥结构反应分析。人群步行激励的频率为1.8～2.5Hz,建立天桥结构的三维空间有限元计算模型,计算天桥结构的自振频率,观察其振型模态,分别对天桥结构模拟竖向和横向步行激振,研究分析天桥结构在人群荷载激振下的反应,采取措施避免天桥在使用过程中由人群步行引起共振的可能。(3)采用数值分析的方法模拟张弦桁架结构各节点的风速时程,将所得风速时程转化为风压作用于结构,对结构进行风振反应时程分析,得到结构实时的应力和位移,同时计算结构的风振系数。(4)采用振型分解反应谱法计算天桥结构的地震反应,同时对天桥结构分别输入天津波、EL-CENTRO波和TAFT波加速度时程进行天桥结构进行地震反应补充计算。(5)数值模拟天桥整个施工过程,计算结构的最终内力和位移,并与传统的计算方法进行比较。更多还原

【Abstract】 The paper combines bridge engineering with the characteristic of truss-string structures, adopts truss-string in the superstructure of one overbridge as major load-carrying members, and analyses the platform bridge structure in five facets as follows:(1) Through static structural analysis of the overbridge, it is all defined including the dimensions of the member cross-section, the initial tensioning force of bridges cable and the construction process. Considering huger service loads, the flexibility of the truss is an important factor when the initial tensioning force is defined. In this structure, the bottom chord cable and the suspender are directly combined and intersect in the same plane. Particular nodes which are at the points the cable and the suspender intersect are designed to avoid the influence of contacting with each other.(2) The analysis of the bridge structural response under the pedestrian excitation. The frequency of pedestrian excitation is from 1.8Hz to 2.5Hz.We find the triaxial FEM calculation model,calculate the frequency of the platform bridge,observe its mode shape,simulate the vertical and horizontal pedestrian excitations, analyse the bridge structural response under the pedestrian excitation and adopt measures to reduce the resonance which is caused under the pedestrian excitation.(3) We adopt the numerical analysis method to simulate the time history of the wind speeds, transform the the time history of the wind speeds to wind pressures,analyse the structural wind-induced vibration response ,then acquire the structural stress and displacement and calculate the wind vibration coefficient.(4) The seismic response is calculated by seismic response spectrum method and input the acceleration time history of tianjin wave, El-centro wave and Taft wave to calculate the seismic response.(5) This paper numerically simulates the process that the platform bridge is built, calculates final forces and displacements of the structure, and contrasts this method with the conventional ones.更多还原