RESEARCH ON RESTORING FORCE CHARACTERISTICS OF HONEYCOMBED STEEL BEAM AND WELDED COMPOUND-RING-HOOP COLUMN COMPOSITE JOINTS

摘要

Eight specimens of honeycombed steel beam and welded compound-ring-hoop column composite joints, designed in 4 different types of connection, were tested under cyclic horizontal loads. The restoring force model including a general skeleton curve and hysteretic rule is formed. Two different destruction forms "weak beam-strong column-strong joint" and "strong beam-strong column-weak joint", occurred as the result of the different connection methods. Meanwhile the relevant hysteretic loops changed into well-developed spindle-shape or converse S-shape with the augmentation of displacement. Certain pinch and the development of the ductility of the structure are shown in the curves for different transverse reinforcement ratio in joint core zone and joint stiffness, and the effect on ductility is advantaged. The tri-line load-displacement restoring model and hysteretic rule based on connection and transverse reinforcement ratio are proposed as well as the formulas for calculating the rigidity of either loading or unloading. The regularity of rigidity degeneration of both loading and unloading condition according with exponential law is also concluded in the article. The restoring force model not only reflects the hysteretic character properly but also is conveniently applied to engineering analysis, which is already verified by comparing with the test.