PUNCIIlNG SHEAR TESTS ON COLUMN FOOTINGS

1 INTRODUCTION PUNCIIlNG SHEAR TESTS ON COLUMN FOOTINGS Mikael Hallgren, Dr.Techn., Research associate Department of Structural Engineering Royal Institute of Technology (KTH) SE-100 44 Stockholm, Sweden e-mail: [email protected] Sven Kinnunen, Dr.Techn., Professor em. Department of Structural Engineering Royal Institute of Technology (KTH) SE-100 44 Stockholm, Sweden e-mail: [email protected] Birgitta Nylander, M.Sc. Swedish National Road Administration SE-781 87 Borlange, Sweden ABSTRACT The paper reports the punching shear tests of 14 column footings of reinforced concrete. The main variables were the concrete strength, the ratio of flexural reinforcement, the type of anchorage of the reinforcement, and the type of shear reinforcement. The tests showed that the concrete strength had a strong influence on the punching shear strength. The ratio of flexural reinforcement only slightly influenced the punching shear strength. The type of anchorage did not influence the punching shear strength. The use of inclined bent-up bars as shear reinforcement gave higher punching shear strengths than the use of stirrups. Key words: Punching shear, Column footings, Slabs, Concrete strength, Shear reinforcement, Tests The resistance to the transverse effects of concentrated forces acting on concrete slabs is an essential problem in design of column footings, flat plates and bridge slabs. The design methods should be based on physical models, which in a relevant way describe the behaviour of the structure and consider the mechanical properties of the materials. Based on tests, a physical model for calculation of the punching shear resistance of column supported concrete slabs was developed at the Department of Structural Engineering, KTH /1/. This model was later extended to slabs with shear reinforcement /2/. The circular test slabs - 1 -

PUNCIIlNG SHEAR TESTS ON COLUMN FOOTINGS

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punching shear

column footings

slabs

concrete strength

shear reinforcement

tests