FULL SCALE TEST TO CHECK THE SAFETY AGAINST PUNCHING THROUGH OF THICK FOUNDATION SLABS

DURCHFUEHRUNG EINES GROSSVERSUCHS ZUM NACHWEIS EINER AUSREICHENDEN SICHERHEIT GEGEN DURCHSTANZEN BEI DICKEN FUNDAMENTPLATTEN

FROM TESTS ON FOUNDATION SLABS BETWEEN 30 CM AND 50 CM THICK, WITHOUT SHEAR REINFORCEMENT, IT WAS APPARENT THAT THE AMOUNT OF SHEAR STRESS WHICH COULD BE BORNE DURING FAILURE THROUGH PUNCHING THROUGH DECREASES WITH INCREASING SLAB THICKNESS. IN CONTRAST TO THE CURRENTLY ACCEPTED SHEAR STRESS LIMIT, SAFETY AGAINST PUNCHING THROUGH FALLS TO BELOW NY = 2.1 WHEN THE SLAB THICKNESS REACHES 50 CM. IT MAY BE CONCLUDED FROM THIS THAT THICK FOUNDATION SLABS, WHICH IN PRACTICE MAY BE OVER 2 METRES THICK, ARE INSUFFICIENTLY SECURE AGAINST PUNCHING THROUGH. THIS IS ALSO TRUE FOR THICK HORIZONTAL FLOORS. BY MEANS OF A FULL SCALE TEST ON A FOUNDATION SLAB WITH REALISTIC DIMENSIONS, A LIMIT VALUE IS TO BE DETERMINED FOR SHEAR STRESSES AT FAILURE RESULTING FROM PUNCHING THROUGH. FOR THE EXECUTION OF THE TEST LOADING EQUIPMENT IS AVAILABLE IN WHICH SOIL PRESSURES, WHICH ARE ASSUMED TO BE UNIFORMLY DISTRIBUTED, ARE SIMULATED BY 64 EQUAL INDIVIDUAL LOADS.