Record Details
A method of seismic design for prestressed concrete highway bridge girders
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | A method of seismic design for prestressed concrete highway bridge girders |
| Names |
Lam, Kwok To
(creator) Laursen, Harold I. (advisor) |
| Date Issued | 1967-03-27 (iso8601) |
| Note | Graduation date: 1967 |
| Abstract | The effects of vertical ground motion are particularly significant in the design of highway bridge girders. Conventional codes do not recommend methods for solving the problem. The intent of this work is to suggest an approach for such design. A set of curves for velocity spectra which are the average values of eight components of the four strongest ground motions yet recorded, the curve of Modified Mercalli intensity vs ground acceleration and the seismic regionalization map are the basic materials for this method. From records of the significant earthquakes in the past thirty years, modified factors for the velocity spectra corresponding to different Modified Mercalli intensity have been developed. Thus, the possible support shear or displacement for bridge girders in any seismic region can be found by substituting the modified velocity spectrum into an established formula. In the calculation of the natural period for the prestressed concrete member, the value of I is based on the ultimate strength theorem and a fully cracked section. The bending stress at midspan of the prestressed concrete girder due to the vertical support displacement is calculated by means of an approximate method. An equivalent one-degree system is used to obtain the beam deflection and the participation factor is used to convert this deflection into the actual midspan deflection for the girder. Finally, a numerical example is used to demonstrate the design procedures. This has been done by using the elastic strength theorem to calculate the dead-load and live-load moments and the ultimate strength theorem to check the adequacy of the design for the possible bending moment due to earthquakes. A trial and error method is used for this purpose. |
| Genre | Thesis/Dissertation |
| Topic | Bridges -- Vibration |
| Identifier | http://hdl.handle.net/1957/47863 |
