Joist Jack Beam

Joist Jack Beam

In the projects with steel joist as roof bearing structure, Open joist jack beam can be selected for the solution of bearing heavier secondary structure such as roof vent.

Same with other joist purlin structure, joist jack beam have bottom chord of M or U shape and round rod web. The difference is top chord as H section, square section or round tube which have wider top surface to provide convenient connection place for above adhesive structure. Meanwhile, this top chord has stronger internodal moment for more additional load.

Due to locating near ridge, supporting point out plane for the jack beam bearing roof vent should be considered specially, otherwise, it is better to enlarge the calculation length out plane.

Specification of joist jack beam is indicated as follow:

”TL” means Tuo Liang in Chinese for joist jack beam. In view of web type, it is hard to be showed together due to various changes. The web type will be noted separately when issuing drawings.

FAQ:

1.问: Joist Jack Beam一般采用哪些规格上弦？
答: 一般采用H型或方管，对于12m-18m 柱网的厂房，上弦承载150Kg/m,，可采用H200*150*3.2*4.5的高频焊H型钢或□100*4 的方管等，具体以计算为准。

2.问: Joist Jack Beam与主梁如何连接？
答: Joist Jack Beam与主梁一般采用上弦搁置的方式连接。但是考虑到Joist Jack Beam上弦规格与其他Purlin Span上弦不同，因此，应考虑上弦上表面的高度应协调一致，或者设计中有特别的考虑。

3.问: 托梁上的附属结构必须作用于节点吗？
答: 不一定，因为上弦的平面内刚度较大，而Openstool在分析中已考虑节点弯矩及节点次弯矩对杆件的影响，因此，作用于桁架托梁上的附属结构允许作用于节间，不一定要作用于节点。当然，当节点荷载过大时，应根据设计者的判断按情况调整。