STAAD for INTERCONNECTING PIPERACK 2

[hanxi]

Sirs and Ladies,
Imagine you have 2 piperacks structure perpendicular to each other... How are u going to consider the conditions of members Piperack 1 connecting to members Piperack 2? In this scenario, I will model these piperacks in different Staad files... Will I declare the members of Piperack 1 (nodes connecting to Piperack 2)as Supports or what? If i declare it as support, there will be NO DISPLACEMENT? What can i do to consider deflection?

Hanxi

 

[minorchord2000]

Why don't you run a 3-Dimensional analysis. Model the supports where they actually occur. I am assuming that the piperacks are ultimately supported by the ground. Just provide nodes at the connection points at the rack intersection. Apply your loads to the piperack at the applicable locations.

 

[IFRs]

If the pipe racks are connected with structural elements, then minorchord2000 is certainly on the right track. In addition, boundary conditions and joint fixity are two critical areas of modeling that require particular attention to reasonably represent reality with the model. It is possible that the question is posed here because the two racks are connected only by pipes and the OP is not sure how to represent the loading. In this case, they are independent structures loaded by the pipes that are supported by both racks. Loads to be considered are pipe, liquid, wind, seismic and thermal. Thermal loading also depends on where you have guides, stops and anchors. Also if and where you are using Teflon shoes or other friction abatement devices, expansion joints etc. You may have to assume some percentage of load sharing, or modify the pipe support conditions to make it clear which rack resists which loads.

 

[hanxi]

Thanks a lot minorchord2000 and IFR for your brilliant replies... Actually, my Piperack 1 Staad file prior to posting these querry results show instability at the nodes common to both piperacks because there's is expansion joints (requirement) adjacent to there intersection (2 bays before there intersection)... Now what I've done is I transferred the location of the expansion joints and I've model portion of Piperack 2 as dummy in Piperack 1 (and vice versa) to eliminate instability in Staad... Maybe what I've made is somewhat more realistic.uuu What can u say?

 

[LobstaEata]

If there is an expansion requirement at the intersection of the two racks, then perhaps the common nodes could be modelled by separating the single node into two nodes, then using spring supports at each node. By doing this a better estimate of drift for the expansion joint might be realized, while introducing model stabilty.

Hope this is helpful.