Response of concrete structures to seismic motions (1975)
AuthorsWilby, Grant Keithshow all
In this report the strength and behaviour of model reinforced concrete structures subjected to simulated seismic disturbances are examined. The performance of a closed loop electrohydraulic testing system used in conjunction with a small shaking table is described. This testing system could accurately reproduce seismic disturbances and was used in the testing of a single storey structure and two six storey structures. All structures had a single bay in each direction and they were approximately one fifth of full size. The problems associated with modelling work are discussed and techniques suitable for constructing small scale three-dimensional model reinforced concrete structures are reported. Loading tests were conducted on typical beam and column structural members and the moment-curvature curves obtained are compared with those determined using theoretical methods. Both static and dynamic cyclic lateral loading tests were conducted on the structures and the apparent strengths of the structures under each type of loading are compared. The accuracy of an existing frame analysis program in predicting the displacement response of the model structures to simulated seismic disturbances is discussed and the more important parameters affecting the response are investigated. The experiments revealed that under lateral loading considerable torsion is induced into the lateral beams and that this may be sufficient to cause failure of those beams. A method is presented for calculating the distribution of torsion induced in the lateral beams and for calculating the magnitude of the torsional contribution to the flexural strength of the longitudinal beams. A discussion on collapse mechanisms is included and a design recommendation is made to reduce the likelihood of the structure collapsing by a column sidesway mechanism.