StructuralAnalysis課件.pptVIP

Structural Analysis Structural Analysis Research Group School of Civil Engineering Southwest Jiaotong University Chap 7 Influence Line and It’s Application 7.1 Introduction 7.2 Theory of Static Force and Kinematical Method 7.3 Influence Line of Statically Determinate Beam Based on Static Force and Kinematical Method 7.4 Influence Line under Indirect Load 7.5 Influence Line of Plane Truss 7.6 Maximum Value Calculation and the Most Unfavorable Load Position 7.7 Pure maximum moment value of simple beam 7.8 The envelop diagram of simple beam 7.9 The Most Unfavorable Load Position and Envelop of Continuous beam 7.1 Introduction Concept ：a function expressing the variation of structural reaction force or internal force under unit moving load. The value in the vertical direction (y) represents the value when the unit moving load moves to the position 定义：在单位移动荷载作用下，表示结构反力或内力变化规律的函数图形。某 量Z影响线图的纵坐标y表示单位移动荷载作用在该点时某量Z的值。 Effects ：a basic tool to investigate the unfavorite position and the calculating max value of reaction and internal force 作用：研究工程中作用于结构上的各种实际移动荷载的不利位置和计算结构反 力、内力最大值的基本工具。 Why：since the moving load, the direction and value of support reaction and internal force is changed with the movement of load. due to the requirement for the the under the moving load 为什么引入影响线的概念：在固定荷载作用下，结构的反力、内力是不变的。 在移动荷载作用下，结构的支座反力及各截面内力的大小、方向抖将随荷载位 置的改变而变化。 7.2 Theory of static force and kinematical method Concept: Applying unit load to any position, selecting one coordinate and the x coordinate represents the load location, and calculating the function between the value and load position x, which is called as the influence line equation 静力法概念：将单位荷载放在任意位置，并选定一坐标系，以横坐标x表示 荷载作用点的位置，然后根据平衡条件求出所求量值与荷载位置x之间的函 数关系式，这种关系称为影响线方程。 Theory of static force method Step: (1) Select the coordinate system and set the o point position, and apply F=1 on any position, and expressing the position with variable x (选定坐标系，首先选取原点的位置，然后将F=1置于任意位置，以自变量x表示F=1的作用位置) (2) Calculating the position functio