Ultimate strength design of perforated deep beams

Memon, Gul Hassan (1982) Ultimate strength design of perforated deep beams. MSc(R) thesis, University of Glasgow.

Abstract

The design of deep beams with or without openings is not yet covered by the new British Code CP110 (1972). The CIRIA guide does contain some design guidance for solid deep beams but the design of deep beams with openings is only briefly covered. In both cases the design procedures follow an empirical approach. The current trend in reinforced concrete design is towards the ultimate limit state methods. In recent years proposals have been made for a more rational approach to reinforcement design for in-plane forces. For a given ultimate load, a stress field in equilibrium with external loads is obtained by a linear elastic stress analysis, e.g. finite element analysis. Reinforcement is provided such that the combined resistance of steel and concrete at every point is equal to or greater than the applied stresses. If the equilibrium and yield criteria are satisfied exactly at every point then the entire structure will be converted to a mechanism at ultimate load. In order for this to happen the structure should have sufficient ductility so that redistribution of stresses takes place as cracking occurs. This thesis is concerned with an experimental study of the proposed design method applied to deep beams with openings and in general with the effect of the opening on beam behaviour. The test series comprised of seven specimens of deep beams with and without an opening having different concrete strengths and varying span to depth ratios. The effects of an opening on/ deflections, crack widths, crack patterns, failure mode and ultimate shear strengths were studied. All the beams were simply supported and under two concentrated top loads except one. The beams were loaded in increments without unloading until collapse occurred. The test results indicate that the ultimate loads were higher in beams where an opening is near the beam soffit than in beams where an opening is at mid-depth. In all the tests the experimental ultimate load greatly exceeded the design load. Why this is so is discussed and by using an empirical factor experimental ultimate load predictions are improved. Further analytical and experimental study is recommended.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Additional Information: Adviser: D R Green
• Keywords: Civil engineering
• Date of Award: 1982
• Depositing User: Enlighten Team
• Unique ID: glathesis:1982-72567
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 11 Jun 2019 11:06
• Last Modified: 11 Jun 2019 11:06
• URI: https://theses.gla.ac.uk/id/eprint/72567