Techniques for testing structures permitted to sway

Mechanisms are described that eliminate the restraining effects of the loads and the lateral bracing on test specimens permitted to sway. One mechanism, called the gravity-load simulator, maintains a vertical orientation of load even as a structure sways. The other is a lateral-bracing mechanism which moves freely with a test structure even at large deflections, and it does not require any adjustments during a test. A gravity-load simulator and a lateral-bracing system designed for use in testing full-size building frames on the equipment itself and tests of building frames utilizing the mechanisms show very satisfactory behavior of the gravity-load simulator and the lateral-bracing system. Some actual test setups using the mechanisms are described. Tests on three-story full-size building frames (30-ft high) and a frame-buckling test are included.