基于多目标等效风荷载的变截面门式刚架抗风优化

Wind Effect Optimization of Portal Frames with Varying Sections Based on ESWLs for Multi-targets

轻钢门式刚架结构是单层工业厂房中一种常见的结构形式,风荷载是其结构设计的重要荷载之一.已有抗风优化研究中一般仅考虑单目标的等效静力风荷载,在多个约束条件时不能保证优化结果的准确性.笔者基于风洞试验数据库构造多目标等效静力风荷载,基于最优准则法对单榀变截面门式刚架进行抗风优化设计.分别以工字钢的腹板高度和材料总重为设计变量和优化目标,以柱顶水平位移和跨中挠度为约束条件,基于MATLAB数值平台,编制了抗风优化计算程序.研究表明,多目标等效静力风荷载能够保证约束位移的数值与随机峰值基本一致,在满足约束条件的前提下,优化设计使结构总重降低了23.2%,经济效益明显,且优化后的截面尺寸符合变截面门式刚架的力学特点.

The light-weight portal frames are commonly used in single floor industrial buildings,and wind load is one of the most important design loads.However,previous studies on structural wind effect optimization only considered the equivalent static wind loads （ESWLs） for a single-target,which might cause inaccurate results under multiple constraints.In this paper,the ESWLs for multi-targets are constructed based on the database of wind tunnel tests,and the Optimum Criterion （OC） method is adopted to optimize the wind effect of a portal frame with varying sections.The height of web plates of the joist steel are selected as the design variables,the minimum weight of steel is the objective under the constraints of horizontal displacement at the column top and the vertical deflection in the mid-span.The code is written on the platform of MATLAB.Studies show that constrained displacements under ESWLs for multi-targets are consistent with the peak random displacements.The optimization makes the total weight decrease by 23.2％,generating obvious economic benefits.Moreover,the optimized sectional dimensions conform to the mechanical characteristics of portal frames.