Effect of support condition and load arrangement on the shear response of reinforced concrete beams without transverse reinforcement

• A test program on beams with different support and load.
• The test results show a positive influence of the moment on the shear resistance.
• Furthernore, the influence of the flexural crack pattern is considerable.
• The experimental observation is discussed and compared with different models.

This paper presents an experimental program on fourteen rectangular beams without transverse reinforcement differed by three support conditions, i.e. simply supported, cantilever and continuous beams, and two load configurations, i.e. one-point and uniformly distributed load. With the chosen test set-up, almost all M/V-combinations commonly encountered in practice can be investigated. The test results indicate significant differences of the shear response of members having the same cross-sectional properties but diverse M/V-combinations resulting from different support conditions and load arrangements. The shear resistance of the simply supported beam subjected to a uniformly distributed load is higher than that of similar beams subjected to a one-point load; the shear resistance of the cantilevers subjected to a uniformly distributed load is higher than that of simply supported beams; the shear resistance for cantilevers subjected to a uniformly distributed load with a longer cantilever arm is higher than for the shorter cantilevers having the same cross-sectional parameters. Furthermore, the slenderness and the flexural crack pattern have been found to decisively affect the critical shear crack formation, hence the shear resistance of continuous beams. The observed response is discussed and explained using a new approach recently developed by the authors. Comparison to the shear resistances predicted by formulas included in some codes of practice is also provided.