Seismic responses of a tilt -up building with segmented walls

Tilt-up construction is widely used for low-rise commercial and industrial buildings. It has been estimated that there are more than 20,000 tilt-up wall buildings in Southern California. Although economical to build, this type of construction has been subject to significant damage in past earthquakes. Prior to about 1970, cast-in-place pilasters connected the tilt-up wall panels. Recent trends in the design of tilt-up wall buildings has been toward the use of segmented wall panels that are connected by welded plates at two or three locations over the height of the panel. It has also been suggested that in seismic regions panels should be connected in pairs or at most in groups of three. In both conditions, chord steel at the top if the panel is provided. The purpose of this study is to evaluate the effects of strong ground motions having pulse type displacement characteristics on this type of tilt-up wall construction. Strong ground motions considered in the study include records from the 1979 Imperial Valley Earthquake, 1992 Landers Earthquake and the 1994 Northridge Earthquake. Critical comparisons and evaluations are made relative UBC design requirements.;In order to investigate the seismic behavior, a prototype building which is a single story, tilt-up wall building having a 200 x 100 foot plan is designed according to the lateral force requirements of the 1997 Uniform Building Code (UBC). Three dimensional, linear and nonlinear models of the prototype building are developed within the constraints of the computer program, SAP2000. Nonlinear elements are incorporated for the connections of the glulam beams and purlins to the wall panels and the nonlinear behavior of the diaphragm is modeled with a Hrennikoff framework model of the continuum. Inelastic characteristics for these components are obtained from the results of a limited number of component tests conducted at the University of California/Irvine. A third building model was developed having cast-in-place connections (pilasters) between the panels. This modeling permitted a comparison between the traditional pilaster construction and the more modern segmented wall construction. In addition, the effects of dense nailing and sparse nailing in the diaphragm are considered.;Results of these analyses indicate that the use of segmented panels in tilt-up wall construction is a viable procedure for buildings located in seismic regions. However, it is important that tests be conducted on the various connections used to tie the components of this system together and that their strength and ductility in the post yield region be determined. Based on the results of these tests some additional strengthening of critical connections may be required to provide the necessary strength and ductility.