现代木结构建筑建造技术 第十四章 椽条，顶棚搁栅与屋盖搁栅选择 第十四章 椽条，顶棚搁栅与屋盖搁栅选择.ppt

练习一 第三步 – 根据树种、等级及间距确定最大允许跨度 26 练习二 以下椽条最大允许跨度多少？ 荷载标准值： 1kN/m2 屋面材料： 混凝土瓦 是否支撑吊顶： 否 椽条尺寸： 40 x 90 mm 椽条间距： 600 mm 树种： 花旗松-落叶松 等级： Ic  27 要点 Key Points: 练习四，确定椽条的最小尺寸For Exercise #4, determine the minimum allowable size for these roof rafters. * 要点 Key Points: 首先确定椽条的最大支撑间水平净距The first step is to determine the maximum unsupported distance that the roof rafters span. 这里使用了连杆之后，最大支撑间水平净距为2.40mFor this exercise, the largest span of the roof rafters is 2.40 m due to the intermediate support provided by the collar ties. 如果没有使用连杆，最大支撑间水平净距将为3.6mIf the collar ties were not used, the rafter span would increase to 3.6 m. * 要点 Key Points: 通过查找“屋盖1”椽条跨度表，llc/lllc 级 40 x 90 mm SPF 间距为600mm的最大允许水平跨度为2.3mFrom the ‘Roof 1 Roof Rafter’ table, the maximum distance that a 40 x 90 mm SPF Grade llc/lllc rafter will span is only 2.30 m when spaced at 600 mm. 题目中需要跨度至少为2.40m，故需要更大尺寸的构件 如此，40 x 140 mm 为此题最小尺寸Since we require a rafter that will span at least 2.40 m, we will need to specify a larger size of lumber for the rafter.In this case, a 40 x 140 mm rafter will be required for this particular application. * 要点 Key Points: 想了解有关本讲更多的信息，推荐学生阅读加拿大木业协会编撰的《施工指南》第9章：屋盖及附录O：跨度表标准For more information about the topics covered by this lesson, it is recommended that students review Chapter 9: Roof Framing and Appendix O: Span Table Criteria in the Guide to Good Practice published by Canada Wood * 要点 Key Points: 有同学有任何问题或不解的地方吗？Do the students have any questions or require clarification about anything presented in this lesson? * * 要点 Key Points: 本讲义中，某术语第一次出现时将会以下划线标记。The first time a new term appears in this presentation and hasn’t appeared in an earlier presentation, it is underlined and appears in this ‘Glossary of new terms’. 术语表并不是教学内容It is not intended that this glossary be part of the presentation. 术语表只是为方便学生理解参考课堂内容This glossary is a reference for students who may be unsure of the meaning of new ter