In reinforced concrete (RC) structures, wide RC beams are used as primary structural members to support floor loads and to transfer forces from the floor to the vertical elements which are below them, e.g. columns and walls. In these cases, wide concrete beams may be loaded and supported by wide columns or walls (full-width loads and supports) and/or by narrow columns (partial-width loads and supports). In both cases of support and load conditions, the one-way (beam) and two-way (punching) shear capacities should be checked for wide RC members. For both wide and narrow load/support configurations, the provisions of current design Codes require that one-way shear capacity is assessed for a cross-section involving the full width of the beam, and the contribution of shear strength resisted by stirrups is assessed according to the longitudinal stirrup-legs spacing where the transverse stirrup-legs spacing is neglected. Moreover, the current design Codes neglect the load and support widt hs to predict the flexural strength. The main concern is whether the requirements of current design Codes may lead to poor predictions of flexural and shear strengths of wide concrete beams, especially for narrow-supported wide beams, because they ignore the support width, load width, longitudinal and transverse spacing of stirrup-legs. The objective of this study is to develop new Prediction, Detailing and Design Models for wide reinforced concrete beams to be used in Practice. The results of 26 tests on wide RC beam specimens are reported in this study. The models were developed to account for the missed parameters mentioned above which showed an actual influence on the flexural and shear strengths of wide RC beams with full- and narrow- width loads and supports (wide- and narrow- supported wide RC beams). They take into the consideration the load- and support- widths (or at best, the ratios of load- and support- width to the beam-width). Comprehensive verifications and evaluations of the proposed models were conducted for comparing them with the existing design Codes and other proposed models. It is shown that the proposed models perform the best among the existing Codes and models. It is shown that the flexural and shear strengths decrease as the ratio of the load- and/or support- width to the beam-width decreases, while the shear strength resisted by stirrups contribution decreases as the transverse stirrup legs spacing increases. These influences occur for members with and without shear reinforcement. Based on the proposed design model, the longitudinal and transversal stirrup legs spacing are reduced as the ratio of the load- and/or support- width to the beam-width decreases, and then this will enhance to increase the shear strength; therefore, the failure mode will change from brittle to ductile manner. These influences occur for members with shear-reinforcement. For the members without shear-reinforcement, the proposed detailing approach will enhance t he flexural reinforcements (tensile and compressive bars) when they are distributed according to their portions of concentrations within the effective-widths of supports and loads. For wide RC beams with and without shear-reinforcement, test results showed that the shear strength decreased as the support-width and/or load-width was reduced. In addition, for wide RC beams with shear-reinforcement, tests results showed that the shear strength decreased as the longitudinal or transverse spacing of stirrup-legs increased. The tests results also showed that the flexural strength of wide RC beams with stirrups decreased as the support-width and/or load-width was reduced. Author keywords: Wide Beams; Existing Codes and Models; Stirrup Leg Spacings; Load and Support; Proposed Prediction, Detailing and Design Models.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:618869 |
| Date | January 2014 |
| Creators | Alluqmani, Ayed Eid |
| Publisher | University of Strathclyde |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=23508 |
Page generated in 0.0023 seconds