Analysis of Dowel Action in Reinforced Concrete Beams with Shear Reinforcement

The shear transfer mechanism was examined to view the contributions of different components of shear transfer such as aggregate interlocking, dowel force and uncracked compression zone. Understanding the role of various shear transfer components with transverse reinforcement provided was complex due to traditional difficulties involved in detail assessment of accompanying kinematics during the failure. In the present paper, the issue was addressed by employing sixteen specimens and grouped under two categories representing conventional beams and beams with preformed cracks and were tested under four - point bending load with a shear span to depth ratio of 1.26 by increasing the characteristic strength of concrete. From the results obtained, empirical formulas proposed were also evaluated and it was concluded that the results were consistent and contribution of shear transfer across uncracked compression zone was maximum in shear resistance with transverse reinforcement provided. Later structural behaviour was also assessed and it was concluded that beams with preformed cracks had exhibited greater stiffness thus nullifying the effect of aggregate interlocking in shear transfer.

Longitudinal shear in composite deck slabs using corrugated steel sheets

Profile deck steel sheets are used in composite deck slabs. These sheets are standard in dimensions and shapes besides they are supplied with embossments and indentations. Such sheets are not available in Iraqi markets nowadays therefore people used another type of sheets which are corrugated without embossments or indentations in very wide range. This study covers the use of such sheets in composite slabs as decks instead of standard profiled steel sheets. The study comprises testing slabs of dimensions 0.9 × 2.5 m reinforced by steel fabric mesh and rested on corrugated sheets. Two types of shear spans are selected shorter and longer to study the longitudinal shear force transmitted due to the applied loads according to the Eurocode 4. The shorter shear spans are 600, 500 and 400 mm while longer one is 800, 750 and 700 mm. The study extended to support the requirements of design equation of the Eurocode by shear bond method also known as m–k method. The evaluated values of m and k are 0.094 and 65 respectively. The result of k which plays a very important role in shear transfer is small compared to what available in literature, therefore it is recommended to make use of shear connectors in such construction or any else method.

Experimental Evaluation on Components of Shear resistance of Reinforced Concrete Beams with Shear Reinforcement Provided

The contribution of aggregate interlocking and dowel force in shear strength of reinforced concrete beams was topic of research for many years. The precise forecasts of shear behavior were challenging to determine due to complication involved. The existing theories had focused on aggregate interlocking force and shear resistance arising due to concrete compression zone, neglecting the contribution of dowel force despite considering as significant constituent in shear transfer mechanism. The present investigation focuses on cogitating all components in shear transfer mechanism by providing shear reinforcement and keeping clear cover and effective span to depth ratio constant. Sixteen specimens were considered for parametric study by employing suitable variables such as increase in strength of concrete and variation in flexural reinforcement. Eight specimens were conventional beams and the remaining eight specimens were provided with preformed cracks. Moment vs. displacement curvature and strain vs. moment curvature were plotted to evaluate shear at uncracked compression zone and accordingly aggregate interlocking force and dowel force were determined based on the empirical formulas proposed. From the result it was confirmed that contribution of aggregate interlocking force and dowel force were insignificant and shear resistance due to uncracked compression zone is the sole contributor in shear transfer mechanism. Structural behavior of concrete beams was also studied and it was confirmed that beams with preformed cracks exhibited better structural behavior when related to conventional beams.