The Reliability Analysis Of Reinforced Concrete Slabs In Punching Shear

Test data for interior column-flat plate connections and column footingsconnections subjected to concentric gravity load were collected and selected,thus a test databank on punching test was been established.Compared with thetest data and four main criterion of punching shear strength:GB50010-2010,ACI318-2008,EN1992-1-1:2004EuroCode2and Ying Tian’s equations.Based on this paper,the contribution of concrete strength and slab flexuralreinforcement is best described by assuming the punching strength to be prop-ortional to (fc)1/3and (rfy)1/3,respectively.Moreover the punching strength canbe best described when the critical section location is2h0from the column.Areview of the data indicated a pronounced tendency toward decreased the ratioof measured strength to calculated strength with increased slab depth.Fromtest data,equations for connection gravity load capacity as a function of concr-ete strength,slab reinforcement ratio and yield strength,slab effective depthand the size effect of slab depth were developed.Calibrated of Code for Design of Concrete Structures of China(GBJ10-89and GB50010-2010) in shear strength formula and punching shear strengthformula.Reliability indexeses were calculated on different concrete strengthgrade(C15to C80),limit state (shear and punching),loads form(concentratedloads,distributed loads,flat-plate and footings),slab flexural reinforcementratio,and ratio r of live load to dead load,according to the different methods(Rackwizt-Fiessler procedure and Monte Carlo simulation).For the revise of punching shear capacity formula of Code for Design ofConcrete Structures of China,the following three suggestions are putted forwa-rd,according to the result of regression analysis and reliability analysis:first,itis necessary to consider the slab flexural reinforcement yield strength and rat-io on the punching shear capacity;second,it is oblige to take the size effect ofslab depth into account in a wider range on the punching shear capacity;thelast,appropriately reducing punching shear capacity and raising punching reli-ability indexes on the existing basis is significant.