Experimental Study On Mechanical Behavior Of Column Lapped Joints For Fabricated Structure

A new type of column to column joint lapped near the contraflexure point of thenew RCS hybrid frames is proposed to meet the needs of the industrial developmentof high-rise building industry in our country. The joint is located by the cup of thelower column and the tenon of the upper one. Then, the longitudinal reinforcement iswelded for temporarily fixation. Finally, the CGM grouting material is poured tofinish the construction of the columns. Such new lapped joints have excellentconstruction efficiency and credible mechanical behavior.Seven full scale assembled columns were tested under axially compression and onewas tested under eccentrical load. Following works were mainly carried out:(1)experimental study of the axial and eccentrical compression behavior of columnswithout pouring CGM grouting material in the lapped joints;(2) experimental studyof the axial compression behavior and the construction performance of the assembledcolumns with different curing time;(3) the compression mechanism is analyzed andthe calculation method of specimens is proposed;(4) design recommendations andconstruction proposal are suggested. It is indicated that the peak load of the RCassembled columns without pouring CGM grouting material is2564kN，which is46.2%of the peak load of the contrastive RC columns. The peak load of the RCassembled columns is slightly lower than the RC columns poured monolithicaly. Withthe increase of curing time, the peak load of the RC assembled columns increased.The failure mode of the RC assembled columns is different from the contrastive RCcolumns. The cup of the lower column is pushed outward due to the squeeze of thetenon of the upper column, with expansion following till finally failure commenced.The specimens show good ductility compared with the RC columns.Shear and flexural test of six full scale assembled columns were carried out toinvestigate the influence of the stirrup ratio and details in the lapped joints to theshear and flexural behavior of specimens, respectively. It is indicated that the shearstrength of RC column assemble joint increases with the increase of stirrup ratio. It isadequate to have2composite hoops setting in the lapped joints to achieve higher shear strength than the contrastive RC columns. The yield strength of the assembledRC columns is5.3%higher than the contrastive column, while the stiffness is almostthe same. The detail proposed in this paper for the assembled columns is feasible.