前言:这是CSA A123的第四版。21，薄膜屋顶系统的动态抗风扬阻力的标准试验方法。它取代了2014年、2010年和2004年出版的之前版本。本标准基于国家研究委员会（NRCC）正在进行的研究和测试。本版本适用于北美的大多数商用屋顶组件，分为三个不同类别，具体取决于与基材的部件连接，即粘合剂应用薄膜屋顶系统、机械连接薄膜屋顶系统和部分连接（混合）薄膜屋顶系统。 CSA集团承认，该标准的制定部分是由于财团成员的财政支持。本标准的制定符合加拿大标准委员会对加拿大国家标准的要求。CSA集团已将其作为加拿大国家标准发布。范围:1.1本试验方法确定了薄膜屋面系统在承受动态风荷载循环时的抗风扬阻力。试验方法适用于a）机械连接薄膜屋面系统； 和b）粘附膜屋面系统。屋顶系统由甲板和屋顶薄膜组成。它包括防潮层或缓凝剂、隔热层、盖板等部件。它受到根据风压记录开发的动态荷载序列的影响，模拟风对薄膜屋顶组件的影响。注:屋顶薄膜可指定为气密性平面。1.2以下限制适用于本标准中的试验方法:a）方法1:根据本试验方法进行的试验仅限于机械连接的薄膜屋顶系统，其紧固件排间距不大于2896 mm（114 in），紧固件间距为- 线间距不大于610毫米（24英寸）。b） 方法2:根据本试验方法进行的试验仅限于附着的薄膜屋面系统。1.3以SI（公制）单位给出的数值为标准。括号中给出的值仅供参考。1.4在本标准中，“应”用于表示要求，即用户为遵守本标准而有义务满足的规定；“应该”用于表示建议或建议但不需要的建议；“可”用于表示一个选项或在标准范围内允许的选项。 注释随附条款不包括要求或替代要求；随附条款的注释的目的是将解释性或信息性材料与文本分开。表和图的注释被视为表或图的一部分，可以作为要求编写。附件被指定为规范性（强制性）或信息性（非强制性）以定义其应用。

Preface:This is the fourth edition of CSA A123.21,Standard test method for the dynamic wind uplift resistance of membrane-roofing systems. It supersedes the previous editions published in 2014, 2010, and 2004.This Standard is based on the ongoing research and testing that is being carried out at the National Research Council (NRCC).This edition is applicable to the majority of the commercial roof assemblies in North America under three different categories depending on the component attachment to the substrate, namely adhesive applied membrane roofing system, mechanically attached membrane roofing system and partially attached (hybrid) membrane roofing system.CSA Group acknowledges that the development of this Standard was made possible, in part, by the financial support from the consortia members.This Standard has been developed in compliance with Standards Council of Canada requirements for National Standards of Canada. It has been published as a National Standard of Canada by CSA Group.Scope:1.1This test method determines the wind uplift resistance of membrane-roofing systems when subjected to dynamic wind load cycles. The test methods are applicable toa) mechanically attached membrane roofing systems; andb) adhered membrane roofing systems.The roofing system consists of a deck and roofing membrane. It includes components such as vapour barriers or retarders, insulation, cover board, etc. It is subjected to a dynamic load sequence that has been developed based on wind pressure records, simulating the effects of wind on membrane-roof assemblies.Note:The roof membrane may be designated as the plane of air tightness.1.2The following limitations apply for the test methods in this Standard:a) Method 1: Testing in accordance with this test method is limited to mechanically attached membrane roofing systems having a fastener row separation not greater than 2896 mm (114 in) and fastener in-line spacing not greater than 610 mm (24 in).b) Method 2: Testing in accordance with this test method is limited to adhered membrane roofing systems.1.3The values given in SI (metric) units are the standard. The values given in parentheses are for information only.1.4In this Standard, "shall" is used to express a requirement, i.e., a provision that the user is obliged to satisfy in order to comply with the standard; "should" is used to express a recommendation or that which is advised but not required; and "may" is used to express an option or that which is permissible within the limits of the Standard. Notes accompanying clauses do not include requirements or alternative requirements; the purpose of a note accompanying a clause is to separate from the text explanatory or informative material. Notes to tables and figures are considered part of the table or figure and may be written as requirements. Annexes are designated normative (mandatory) or informative (non-mandatory) to define their application.