| In this paper, the cloud tower is frame-reinforced concrete core wall structuresystem in which the frame is composed of concrete filled steel tubular column、girderand composite slabs. The locational seismic fortification intensity is7. The buildingbelongs to super high-rise building in height (185.1m) and plane layout is irregular. Inorder to guarantee the safety of structure withstanding seismic motion, aiming at thetubular joint at the corner of the11th floor of combination frame, four large dimensionspace joints are made to conduct monotonic static and cyclic repetitive loading test inhollow and filled with concrete respectively.In the test,the axial capacity of joint、failure mode、stress distribution in intersecting area、elastic and plastic development oftubular joint on both sides of weld seam under both two loads are the first purpose.Then, the effectiveness of the structural measures which is conducted to ensuremechanical property of joint are verified secondly. At last, the finite element analysis iscompared with experimental results for verifying the rationality and reliability of thetest, the main work is as follows:①The first group of tests includes one Hollow steel tube space joint and oneconcrete filled steel tubular space joint, namely joint (1) and joint (2) respectively. Thetwo joints are brought to bear monotonic static loading to study the ultimate capacity ofthe joints,the elastic-plastic development tendency in intersecting area and failure modein hollow and filled concrete.②The second group of tests have the same joints with the first one，namely joint(3) and joint(4) respectively.The both two are brought to bear cyclic repetitive loadingto study the improvements on the seismic performance of concrete filled.③The finite element analysis is compared with the results of first pair of jointsbearing monotonous static load to verify the rationality and reliability of test results.The stress and strain of concrete filled in joints and the pulling plate are simulated assupplement in the tests.Based on experimental researches and analysis, the main conclusions are as follows:①The failure modes of four joints under monotonic static and cyclic repetitiveloading are buckling in straight pipe of joints. The ultimate axial bearing capacity ofhollow joints reaches the designed value, and the ultimate axial bearing capacity ofjoints filled concrete reaches two times the designed value. The stress of steel and the intersecting area of joints filled with concrete are less than the yield strength when theloads reach designed value.At the same time,the joints maintain axial capacity in spiteof partial region reaching or exceeding yield strength, indicating that the joints filledconcrete are safe and reliable in design;②Under cyclic repetitive loading，the plastic development of intersecting area onboth sides of weld seam can be restrained effectively by the concrete filled in joint andthe increase of plastic strain is uniform and linear during plastic stage. As a result, theconcrete can postpone the joint stiffness degradation when the stress of partial regionreaches the yield point;③Under monotonic static and cyclic repetitive loading, the plastic strain of areacloser to intersecting area is much smaller than that of farer area, realizing the seismicdesign philosophy,"strong joint weak component", with better energy dissipatingperformance;④In finite analysis the capacity of joint(1) and (3) are similar with theexperimental results when reach100%and180%designed value in monotonic staticloading basically.The intersecting area of joints remain in perfect condition and the VonMises of straight pipe is most negative. |
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