Jun 30, 2005 #1 damo74 Structural Jan 18, 2005 56 Has anyone any idea on how I could calculate the natural frequency of a concrete bridge beam?
Jun 30, 2005 1 #2 GregLocock Automotive Apr 10, 2001 23,771 Sure. Best way, to be honest, is FEA, but if it is a single span uniform beam supported at each end then the first mode is given by f=1/2/pi*A*sqrt(E*I/mu/L^4) Hz For simply supported A=9.81, for fixed fixed A=22.4 mu=mass per unit length All units are consistent. The book you need is by Robert D Blevins Cheers Greg Locock Please see FAQ731-376 for tips on how to make the best use of Eng-Tips. Upvote 0 Downvote
Sure. Best way, to be honest, is FEA, but if it is a single span uniform beam supported at each end then the first mode is given by f=1/2/pi*A*sqrt(E*I/mu/L^4) Hz For simply supported A=9.81, for fixed fixed A=22.4 mu=mass per unit length All units are consistent. The book you need is by Robert D Blevins Cheers Greg Locock Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
Jul 1, 2005 #3 Bbird Civil/Environmental Aug 6, 2003 140 Normally the first nat freq would lie somewhere in between simpply supported and fully fixed conditions, both are well defined by the textbooks. Should use them for sanity check after FEA work. Upvote 0 Downvote
Normally the first nat freq would lie somewhere in between simpply supported and fully fixed conditions, both are well defined by the textbooks. Should use them for sanity check after FEA work.
