Study On The Performance Of H-beam To Square Tubular Column Connections With Outer-shell

In recent years, frame structures composed of square steel tubular column and H-shaped steel beam have become one of the major representations in the development of steel structure of residential buildings. At present, there are three kinds of joints type for this kind of structure. They are separately the joint with interior diaphragms, the joint with through diaphragms and vertical stiffener joint. When Northridge earthquake and Osaka-kobe earthquake happened, weld cracking was found at joint with interior diaphragms and joint with through diaphragms, which would break the seismic behavior of the whole structure. Construction of the vertical stiffener joint is complex and it will occupy more architectural space. For all these reasons, it's necessary to develop new joint style. With the background, the chief research content is presented as follows:The research application status of H-beam to square tubular column connections was summarized. Advantage and disadvantage of several common H-beam to square tubular column connections were analyzed. And then the main work was presented.Based on brief introduction of basic requirements of the new type connections, inner-tube connection and outer-shell connection were presented. Their basic structure forms were introduced. With comparison of mechanical property, construction technique and cost, it comes to conclusions that outer-shell connection is better than inner-pipe connection. And the outer-shell connections would be taken as the research object.Yield line theory was introduced and formulas of the yield bearing capacity were derived with yield line theory and principle of virtual work. Nine more failure modes were analyzed to provide reference for the quasi-static test.The quasi-static tests of three full-scale cruciform specimens were designed and carried out to study the seismic behavior of the outer-shell connection. The failure process and feature of each specimen and the stress transfer mechanism in the connection zone was analyzed. Through analysis of strain gauge, the yielding sequence of the new type connection and the stress distribution regular of the core region would be obtained. Based on the measured hysteresis loops, skeleton curve and M -θcurve, this paper made a thorough comparing analysis on the index of seismic behavior such as load-carrying capacity of the joint, ductility, energy dissipation, rigidity degeneration and shear deformation. The results show that this new-type joint has a good seismic behavior. Through analysis of strain gauge, the yielding sequence of the new type connection and the stress distribution regular of the core region would be obtained.FET software ANSYS was used to simulate the quasi-static test. The analytical results, including hysteresis loops, skeleton curve and M -θcurve, accord with the experimental ones very well. Then design parameter analysis for joint was carried out through finite element method so as to find out the influence of outer-shell thickness and T-stub dimension on joint behavior.Five types of classification of beam to column were introduced. With Eurocode3 and Bjorhovde method, it is confirmed that this new type connection should be categorized as semirigid connection.At last, several problems of outer-shell connections which needed researched more deeply were put forward.