几何尺寸与公差论坛------致力于产品几何量公差标准GD&T (GDT:ASME)|New GPS(ISO)研究/CAD设计/CAM加工/CMM测量  


返回   几何尺寸与公差论坛------致力于产品几何量公差标准GD&T (GDT:ASME)|New GPS(ISO)研究/CAD设计/CAM加工/CMM测量 » 三维空间:产品设计或CAX软件使用 » CAD设计 » 产品功能分析
用户名
密码
注册 帮助 会员 日历 银行 搜索 今日新帖 标记论坛为已读


回复
 
主题工具 搜索本主题 显示模式
旧 2009-09-08, 08:21 PM   #1
huangyhg
超级版主
 
huangyhg的头像
 
注册日期: 04-03
帖子: 18592
精华: 36
现金: 249466 标准币
资产: 1080358888 标准币
huangyhg 向着好的方向发展
默认 eccentricity in steel columns

eccentricity in steel columns
a statement was mad to me that when designing a steel column with steel beams framing into it with simple shear connections, it is not necessary to account for the bending moments caused by the eccentricity of the beam reactions. he said that because the clip angle connections actually resist some moment, the effective length of the column is really less than 1, and that this counteracts the effect of the bending moment.
i disagree because the clip angles are not designed for moment transfer, so you shouldn't count on them lowering the effective length of the column, and that you should consider the moment from the eccentricity of the beam reactions.
i would like to know what others think about this, please give me your comments. thanks.
i consider this type situation to be a matter of priorities. the moments that you are considering exist, but their magnitude is probably lost in the approximations needed for column design, such as selection of the "k" value. since most structural failures occur at connections, rather than in
i see your point slideruleera, thanks for the response. also, i never select a column that is "maxed out" for its allowable axial load, so this extra capacity would also help deal with these moments. my friend gave me this quote about structural engineering that is relevant to this discussion:
"the art of molding materials we do not really understand
into shapes we cannot really analyze
so as to withstand forces we cannot really measure."
i usually assume a moment is generated at the connection by the eccentricity of the load transfer point (ie the bolts). the clip angle will have to deal with a small amount of moment due to this load, lever arms, etc. the column will have to deal with a small moment as generated by the connection.
having said this i treat the beam as pin ended, the column as under combined axial load and moments and the connections as mainly shear but with a small moment in the connection plate.
in reviewing my as constructed designs i have not had a failure yet with this approach. also as a rule of thumb as i deal mainly with housing, i always specify a minimum of 2/m16 8.8/s bolts and 10thick plates for these types of connections. in a lot of cases this is over designed but the extra cost of the plate and bolt size increases is less than the cost of me doing the calculations when i know from experience that these sizes will work for 95% of the housing work i do.
regards
sc
i believe that spring of 2002, osha instituted a new rule that requires that columns support a certain amount of moment for erection purposes. how does that requirement stack up against bjb's question. is the osha requirement, in general, larger or smaller than the load expected in bjb's question?
__________________
借用达朗贝尔的名言:前进吧,你会得到信心!
[url="http://www.dimcax.com"]几何尺寸与公差标准[/url]
huangyhg离线中   回复时引用此帖
GDT自动化论坛(仅游客可见)
回复


主题工具 搜索本主题
搜索本主题:

高级搜索
显示模式

发帖规则
不可以发表新主题
不可以回复主题
不可以上传附件
不可以编辑您的帖子

vB 代码开启
[IMG]代码开启
HTML代码关闭

相似的主题
主题 主题发起者 论坛 回复 最后发表
designing columns for concrete buildings huangyhg 产品功能分析 0 2009-09-08 06:12 PM
cross bracing within steel stud wall huangyhg 产品功能分析 0 2009-09-08 03:57 PM
coninuous steel beams over columns huangyhg 产品功能分析 0 2009-09-08 01:09 PM
concrete basement wall cast around steel columns huangyhg 产品功能分析 0 2009-09-08 11:39 AM
4 story wood building with steel beams and columns at the fi huangyhg 产品功能分析 0 2009-09-07 08:45 AM


所有的时间均为北京时间。 现在的时间是 12:56 PM.


于2004年创办,几何尺寸与公差论坛"致力于产品几何量公差标准GD&T | GPS研究/CAD设计/CAM加工/CMM测量"。免责声明:论坛严禁发布色情反动言论及有关违反国家法律法规内容!情节严重者提供其IP,并配合相关部门进行严厉查处,若內容有涉及侵权,请立即联系我们QQ:44671734。注:此论坛须管理员验证方可发帖。
沪ICP备06057009号-2
更多