JackBolt
Structural
- Jul 9, 2005
- 17
Petrochem industry
I am reviewing a very large pile-supported mat which will support 2ea heavy pieces of equipment. The geometry of the mat is oversized relative to the equipment as it will also be used to support a lifting tower needed to set the equipment in place. STAAD software was used to analyze the foundation using plate elements w/springs representing the piles. The vertical shear stresses at the edge of the mat are practically zero. The shear stresses near the reactor pedestals are very high...say 200psi.
Questions:
(1) Is a check for one-way beam shear required?
(2) If 'yes' above, do you look at say the worst case 1-foot wide strip to determine the design shear loads? Do you have a reference which states you should use a 1-foot wide strip?
(3) Can you take the average shear stress across the mat width as typically done with smaller spread footings?
Note: before answering number 3 above, please note the mat width is almost 80feet wide. The higher stress concentration is limited to say 2ea 15-foot wide sections in the middle of the mat. The concern here is an averaging of the design stress may result in underdesign.
Thanks in advance,
I am reviewing a very large pile-supported mat which will support 2ea heavy pieces of equipment. The geometry of the mat is oversized relative to the equipment as it will also be used to support a lifting tower needed to set the equipment in place. STAAD software was used to analyze the foundation using plate elements w/springs representing the piles. The vertical shear stresses at the edge of the mat are practically zero. The shear stresses near the reactor pedestals are very high...say 200psi.
Questions:
(1) Is a check for one-way beam shear required?
(2) If 'yes' above, do you look at say the worst case 1-foot wide strip to determine the design shear loads? Do you have a reference which states you should use a 1-foot wide strip?
(3) Can you take the average shear stress across the mat width as typically done with smaller spread footings?
Note: before answering number 3 above, please note the mat width is almost 80feet wide. The higher stress concentration is limited to say 2ea 15-foot wide sections in the middle of the mat. The concern here is an averaging of the design stress may result in underdesign.
Thanks in advance,