Dynamic Properties - Wind Tunnel
Dynamic Properties - Wind Tunnel
(OP)
Folks,
My understanding so far has been that when providing dynamic properties (time periods, mode shapes) for wind tunnel testing, the properties are based on service level loads, meaning that the cracking in columns, walls, slabs, beams etc. can be based on a 1.43 * stiffness modifier specified in ACI Chapter 10.
I was recently told to provide dynamic properties based on stiffness values associated with factored loads, meaning much higher periods due to higher cracking at strength (factored) level forces.
ACI mentions that the stiffness EI used in elastic analysis for strength design should represent stiffness immediately prior to failure (meaning crack factors associated with strength level forces). The confusing portion is that in the same commentary, it is mentioned that "....service level loads are to be used for wind tunnel testing".
Can anyone shed some light and explain the nuances of structural properties for wind tunnel testing (for strength and serviceability).
My understanding so far has been that when providing dynamic properties (time periods, mode shapes) for wind tunnel testing, the properties are based on service level loads, meaning that the cracking in columns, walls, slabs, beams etc. can be based on a 1.43 * stiffness modifier specified in ACI Chapter 10.
I was recently told to provide dynamic properties based on stiffness values associated with factored loads, meaning much higher periods due to higher cracking at strength (factored) level forces.
ACI mentions that the stiffness EI used in elastic analysis for strength design should represent stiffness immediately prior to failure (meaning crack factors associated with strength level forces). The confusing portion is that in the same commentary, it is mentioned that "....service level loads are to be used for wind tunnel testing".
Can anyone shed some light and explain the nuances of structural properties for wind tunnel testing (for strength and serviceability).






RE: Dynamic Properties - Wind Tunnel
Thanks
RE: Dynamic Properties - Wind Tunnel
RE: Dynamic Properties - Wind Tunnel
Do you provide building dynamics (periods, mode shapes) for wind tunnel analysis based on stiffness (cracking) at factored loads or service loads?
RE: Dynamic Properties - Wind Tunnel
By concept of strength design, at factor load level around strategic locations of members, the concrete should have cracked to the point that the only concrete region remains intact is the compression zone. In reality, it is not likely to occur, and shouldn't be allowed to occur. Check me on this.
RE: Dynamic Properties - Wind Tunnel
This has been my interpretation also, but our logic is being questioned by a big name firm and I wanted to gather input from other practicing engineers.
RE: Dynamic Properties - Wind Tunnel
Where are our wind/concrete/building experts?
RE: Dynamic Properties - Wind Tunnel
RE: Dynamic Properties - Wind Tunnel
RE: Dynamic Properties - Wind Tunnel
RE: Dynamic Properties - Wind Tunnel
I guess this question was raised during a peer review process. The reviewer shall state clearly theirs objectives, and list all relevant references. If they did not, politely asking them to do so before renders response.
RE: Dynamic Properties - Wind Tunnel
RE: Dynamic Properties - Wind Tunnel
RE: Dynamic Properties - Wind Tunnel
RE: Dynamic Properties - Wind Tunnel
RE: Dynamic Properties - Wind Tunnel
RE: Dynamic Properties - Wind Tunnel
(a few years ago, LOL)
RE: Dynamic Properties - Wind Tunnel
RE: Dynamic Properties - Wind Tunnel
Hope we all agree.
Evergreen :)
RE: Dynamic Properties - Wind Tunnel