Support conditions and failure load of beams above openings

Abstract EN

Experimental investigation of failure load is performed for straight and cambered beams above openings.

Four cases of beam supports were investigated.

These cases are hinge-roller, hinge-hinge, restraint–hinge, and restraint–restraint.

Degree of restraining is normal restraining resulted from masonry walls and beams above these walls.

Bending strains are measured at top and bottom fibers at mid-span.

In compression zone, strains for cambered beams are larger than those for straight beams.

The enhancement ratios ranges from 1.05 at beginning of load application to 1.02 at ultimate load.

In tension zone, strains for cambered beams are smaller than those for straight beams.

The enhancement ratio approximately equal to 0.99 at ultimate load.

Failure loads for cambered beams are greater than those for straight beams.

Maximum enhancement in failure load due to camber is 9.11% for a beam with a high degree of restraints.

(good end restraining) and minimum enhancement is 0.52 % for hinge – roller beam (poor end restraining).

Bending moment are predicted from bending strains and these are less than theoretical bending capacity of the section.

The difference between experimental and theoretical moments is 0.89 kN.m for hinge-roller beams and 0.97 for restraint-hinge beams.