Vincentzack
Structural
- Sep 4, 2009
- 1
Hi! I need to model a circular tunnel which comprises two tunnel linings - inner layer and outer layer. Since the inner layer will be construction after few years of the completion of outer layer. I need to model them with considering staged construction. The loading will be acted on the outer layer once it completed. Thus, there are lock-in stress and deformation in the outer layer shell before the construction of inner layer.
I would like to know how can model this situation in SAP2000. I tried to model the composite action with two separate shells connected by rigid link with staged construction analysis. Both layers are modeled in their centreline (Diameter of inner layer = 1927.5mm and diameter of outer shell = 2152.5mm). The steps are listed below:
Step 1: Use "Add Structure" to add the outer layer shell and apply the loadings (called ground load, surcharge and groundwater) on it. Soil springs (normal and tangential to the shell) are applied to restraint the tunnel.
Step 2: Add the link and inner shell in the structure. Another load (called additional distortion) are applied on the structure (on the outer layer shell).
I referred the following website regarding the rigid link:
Since it is circular tunnel with external pressure, the shells should be under compression force. However, tension force in inner layer shell was found in the result of step 2. Could anyone advise what wrong in my model? And, could give my any suggestion to get correct result?
I have tried that if there are no "U2" and "U3" stiffness of link, both shells will be under compression. However, I don't have idea whether it is correct or not. Could someone give my some advise?
I would like to know how can model this situation in SAP2000. I tried to model the composite action with two separate shells connected by rigid link with staged construction analysis. Both layers are modeled in their centreline (Diameter of inner layer = 1927.5mm and diameter of outer shell = 2152.5mm). The steps are listed below:
Step 1: Use "Add Structure" to add the outer layer shell and apply the loadings (called ground load, surcharge and groundwater) on it. Soil springs (normal and tangential to the shell) are applied to restraint the tunnel.
Step 2: Add the link and inner shell in the structure. Another load (called additional distortion) are applied on the structure (on the outer layer shell).
I referred the following website regarding the rigid link:
Since it is circular tunnel with external pressure, the shells should be under compression force. However, tension force in inner layer shell was found in the result of step 2. Could anyone advise what wrong in my model? And, could give my any suggestion to get correct result?
I have tried that if there are no "U2" and "U3" stiffness of link, both shells will be under compression. However, I don't have idea whether it is correct or not. Could someone give my some advise?