Rigid and Flexible Diaphragm same floor
Rigid and Flexible Diaphragm same floor
(OP)
Hi everyone,
I have 4 story (+penthouse) wooden bldg (rectangular in shape 310'x110') which is partially bearing on concrete floor at second level and partially bearing on concrete floor at first level (i.e.) there is a rigid and flexible diaphragm at second floor level. The joint between two diaphragms cuts the bldg into two squares.
The bldg is in washington and hence we need to check it against lateral forces as well. Now my question is,if I dont provide any seismic gap between two diaphragms would the system work.
My main problem is that if I do provide a gap i have to do it on all of the above floors which is not going to happen in our case. I am scared that due to the connection at second level concrete floor might dump the lateral load onto flexible diaphragm whcih will surely fail or the wooden diaphragm might tear out or rupture due to connection to rigid diaphragm.
Any help on the concept of how this bldg will acutally behave would be greatly appreciated.
I have 4 story (+penthouse) wooden bldg (rectangular in shape 310'x110') which is partially bearing on concrete floor at second level and partially bearing on concrete floor at first level (i.e.) there is a rigid and flexible diaphragm at second floor level. The joint between two diaphragms cuts the bldg into two squares.
The bldg is in washington and hence we need to check it against lateral forces as well. Now my question is,if I dont provide any seismic gap between two diaphragms would the system work.
My main problem is that if I do provide a gap i have to do it on all of the above floors which is not going to happen in our case. I am scared that due to the connection at second level concrete floor might dump the lateral load onto flexible diaphragm whcih will surely fail or the wooden diaphragm might tear out or rupture due to connection to rigid diaphragm.
Any help on the concept of how this bldg will acutally behave would be greatly appreciated.






RE: Rigid and Flexible Diaphragm same floor
You wouldn't check lateral in Texas?
Anyway.. a sketch would definitely help. In the meantime, always remember that load is "attracted" to stiffness.
RE: Rigid and Flexible Diaphragm same floor
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Rigid and Flexible Diaphragm same floor
Otherwise, at each level, and at the interconnection btwn. the wood and conc. diaphragms, look at this like the connection btwn. a large roof diaphragm (the wood frame fl.) and a shear wall (the conc. slab), but they are both in the same plane, so details are a bit different. In a typical warehouse bldg. these two diaphragms are much different in rigidity, and also in perpendicular planes, but we make that detail work. You typically might need some drag struts, blocking, slightly stronger diaphragm near the conc. slab, to transfer the wood diaphragm loads and the loads from the wood framed shear walls. These will be regular shear loads and concentrated loads from the torsion action in plan, all taken into the conc. structure, which can then be designed for these added loads.