Analysis of current methods of flexural design for high strength concrete beams

Considerable amount of research was carried out into the properties and structural performance of high strength concrete for more than few decades. Whilst this research has produced relevant and useful results, there are several properties of high strength concrete like compressive and tensile strengths, stiffness, durability etc. that need to be evaluated and investigated to determine an accurate representation for the determination of different structural properties of beams made of high strength concrete. For this purpose, an investigation into the behaviour of beams made of higher concrete strengths has been carried out and conclusions drawn for the design of high strength concrete beams in flexure. Experimental data from previous research was considered for the study to establish some understanding of flexural behavior of HSC beams. A number of spreadsheets in Excel were developed using available data and various graphs were plotted to determine the accuracy of the code provisions for calculating the ultimate moment capacity of beams. A study on flexural ductility of beams has been carried out using a computer program FRMPHI which generates moment-curvature curves for the beams. Ductility has been studied using ductility factors. The influence of ductility on the value of the depth of neutral axis has been analysed and discussed. A chapter on the short-term deflection of simply supported high strength concrete beams under instantaneous deflections is presented. This chapter includes analysis of the available formula to calculate deflection to determine if these can be adopted for high strength concrete. Extensive ongoing research on the shear strength of beams by several researchers since many years has lead to the generation of a large body of knowledge. Although each author has analysed the data comparing them with existing relationships, the whole body of information has not been analysed to establish a statistical significance. In this study, regression analysis on experimental data collected from published research is carried a relationship between the different parameters affecting the shear strength of beams. The level of significance of the association between parameters influencing shear strength is also discussed