Experimental Study On Punching Shear Performance Of Reinforced Concrete Slabs

The column base plate,flat floor slab column connections and concentrated loads of reinforced concrete flat plate structure,because it has the advantages of simple structure,the force transmission path short,can increase the floor height and is economical and practical,good adaptability and variability characteristics of the structure in the actual engineering application and more widely.With the influence of various complicated factors,such as the foundation plate and the slab with no beam floor,the joint of the plate and column needs to be subjected to the larger concentration force of the plate,so the strength of the joint is difficult to guarantee.Because of the complexity of the problem,there is no agreement between the scholars at home and abroad on the mechanism of the shear failure mechanism,and the focus of the research has mostly focused on the theoretical or experimental research methods.Considering the above factors,the author of a large number of domestic and foreign relevant test data analysis,adopt the method of combining experiment and theory,to this problem are summarized and studied systematically,the main research contents and conclusions are as follows:(1)Through punching test on reinforced concrete slab,and analyzing the punching shear test data of the previous database,the punching shear failure,failure mode,failure process and action mechanism of reinforced concrete slab are understood.(2)Through the analysis of test data of the test and the influencing factors of the reinforced concrete slab punching capacity mainly includes:load perimeter,load position,the tensile strength of concrete,reinforcement ratio,aggregate size,board size effect etc.(3)The results showed:in the condition of a certain length of support plate,if the plate loading area increases,punching capacity is increased and the loading plate,the position in the center plate punching capacity is close to the minimum,the supporting side punching capacity is high.(4)the shear strength of reinforced concrete slabs can be improved by increasing the concrete strength,increasing the reinforcement ratio and increasing the particle size of the coarse aggregate in the reinforced concrete slabs.(5)The British BS,American ACI,Japanese Society of civil engineering and China standard four formula,the foreign and the cutting test of a total of 63 sample data analysis and calculation that the British standard BS formula to calculate the values obtained with this series of tests was compared with the other three the best kind of specification,the test values and the calculation formula of the best agreement;the United States ACI and Japan Society of civil engineers of the experimental values and the calculated values of the ratio is relatively large,the results are more conservative,structural design tends to be safe;Chinese standard,due to less consideration of influencing factors for different test plates,Chinese specification type the test value and the calculated value ratio is larger,more discrete,if calculated as punching strength value in structural design to structural design tends to be safe or unsafe to,detrimental to structural design.