For over 25 years, I have been actively involved in research to understand analytical design methods that can allow the efficient and accurate validation of deflection control in concrete structures.
Deflection control of a structural members is typically considered in relation to the serviceability of a structure. Under normal, everday loading (or the specified loading defined by a building code), will the performance of the structure be impacted by the deflection? Roof systems may not drain water, floor systems may impact the useability of the space, and differential deflections can lead to damage of non-structural components such as windows or brittle finishes.
The research aims to improve the design methods utilized by engineers to verify if predicted deflections will exceed prescribed limits. This requires that the analytical methods to predict deflections are verified, and also that the acceptance criteria is appropriate. The research methodology uses analytical and numerical models to understand the key parameters that influencee deflection, and validates the proposed techniques through new or published laboratory results.
Research has focussed on the primary parameters that are known to influence the deflection in reinforced concrete slabs, including:
The deflection of beams is influenced by many of the same parameters as Slabs. However, the presence of shear reinforcment (i.e. stirrups) and the smaller span-to-depth ratios have been shown to impart additional influences: