Direct Shear Failure in Reinforced Concrete Beams under Impulsive Loading
Abstract
An analytic procedure is developed, using classic elastic Timoshenko beam theory, to define conditions under which reinforced concrete beams and one- way slabs can fail in a direct shear mode when subjected to distributed impulsive loading. The procedure is based on the assumption that incipient failure occurs in direct shear when the beam support shear exceeds a strength threshold before the support bending moment attains its ultimate capacity. The Timoshenko theory is extended to include rotational beam-end restraint and to account for viscoelastic material response to assess qualitatively the influence of rate effects on shear and bending moment. Dynamic failure in direct shear is presumed to behave in accordance with currently accepted static shear transfer mechanisms. Dynamic failure criteria are extropolated from static criteria with the use of an enhancement factor based on increased material strengths due to load rate. Failure curves, defining peak pressure versus rise time domains where direct shear failure is possible, are compared to experimental evidence for specific beam geometries and load rates. Post failure deterministic and stochastic models are introduced as candidates for analysis beyond incipient shear failure. It is concluded that direct shear failures can be predicted for certain combinations of load parameters. Rate effects enhance shear forces more than bending moments during transient response. Strength enhancement due to load rate reduces the domain of load parameters over which a direct shear failure can take place, whereas a relaxation of beam-end restraint increases this domain considerably.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1983
- Accession Number
- ADA133666
Entities
People
- Timothy Jack Ross
Organizations
- Air Force Research Laboratory