脚手架风荷载体系数.doc

扣件式钢管脚手架的风荷载体型系数 赵根涛 （广东省江门市新会区冈州工程建设监理有限公司529100） 摘要：建筑施工扣件式钢管脚手架安全技术规范JGJ130-2001表A-3只给出敞开式单，双排扣件（Ф48×3.5）脚手架的挡风系数φ，欲求风荷载体型系数时还需加上脚手架上吊挂的安全立网的挡风系数。本文着重探讨包括脚手架杆件及安全网的挡风系数，进而便捷求得脚手架的风荷载体型系数。 关键词：挡风系数；风荷载体型系数；挡风面积；迎风面积。 一、前言 建筑施工扣件式钢管脚手架安全技术规范JGJ130-2001（以下简称规范）第4.2.4节关于脚手架风荷载体型系数μs的表达式中的挡风系数φ=1.2An/Aw，其中An为挡风面积，Aw为迎风面积，敞开式单、双排脚手架的φ值宜按本规范附录A表A-3采用。查表A-3发现该表仅为由扣件、钢管构成的挡风系数，而当前的建筑施工安全检查标准JGJ59-99（以下简称标准）规定脚手架外侧设置密目式安全网全封闭。在验算脚手架整体稳定和连墙件时，如何准确求得包括扣件、钢管和安全网在内的挡风系数就显得十分重要。 二、安全网的挡风系数φ1 密目安全网的挡风系数是根据《规范》表4.2.4注2挡风系数φ1=1.2An1/Aw1,又根据《标准》条文说明第3.0.7条，密目安全网的标准是10cm×10cm=100cm2的面积上，有2000个以上网目，工地现行使用的安全网大多按GB16909-1997标准生产，在100cm2一般为2300目，每个网目净面积为0.013cm2，由此可求得： φ1=1.2×An1/Aw1=1.2×（100-nA0）/100=1.2×（100-2300×0.013）/100 =0.8412 式中：An1——安全网的挡风面积 Aw1——安全网的迎风面积 n ——在100cm2的网目数，取n=2300目 A0——安全网一目净面积 三、脚手架杆件的挡风系数φ2 脚手架中具有挡风作用的主要是立杆，大横杆、和剪刀撑，影响φ2值的大小是这些杆件的直径大小和数量，规范附录A表4-3是根据以下经验公式求出： φ2=1.2×An2/Aw2=1.2×（La+Lh+0.325LaLh）） poverty alleviation, making stable poverty of village and exit in a timely manner, should support poverty alleviation into, from the ... The stability of families, not simply one off, not only to help a horse, and giving a lift to prevent poverty and returning again. (D) to co-ordinate the configuration resource for poverty alleviation. One hand to work actively towards a superior policy. Central work Conference of poverty-alleviation, Central Government of General transfer payments, various types of special transfer payments involving the peoples livelihood, in order to further to poor areas. National Revolutionary development seminars presented five closely around the, developed to support development and construction of old revolutionary views. Prime Minister Li keqiang on the CPPCC was specifically proposed in the Government work report: national waste management policies and the peoples livelihood projects to impoverished areas. Meanwhile, provinces and cities will also be supporting the introduction of appropriate policies. Th