Authors

1 Civil Engineering Department, University of Technology, Baghdad; Iraq

2 Civil Engineering Department, University of Technology, Baghdad, Iraq

Abstract

This study investigates the effect of confining the Strut region of the deep beam by using Struts Reinforcement; which consists of four main bars enclosed by stirrups. Six specimens were tested for investigating the behavior of deep beams including; ultimate load, mid-span deflection, crack pattern, first shear and first flexure cracks, concrete surface strain and mode of failure. The specimens were tested under two symmetrical points load with and of 1 and compressive strength of 38 MPa. The main parameters were: first one the diameter of the main bars of Strut Reinforcement (8, 10, 12 mm) with constant spacing of stirrups equal to 80 while the other parameter was varied spacing of stirrups of strut reinforcement (120, 100, and 80 mm) with constant main bars diameter of 8 mm. The test results showed that the Strut confinement generally increased the ultimate load from 750 kN to 1250 kN and the ductility of the beam, confined shear cracks and strain surface across the strut and shear area and turned failures mode from shear failure to flexure. The increase in the diameter of the main bars enhanced the behavior of the beam more than the stirrups number

Keywords

[1] ACI committee-318, “Building code requirements for structural concrete (ACI 318M-14) and commentary,” American Concrete Institute, Farmington Hills, 2014.
[2] P. Nagarajan, T.M.M. Pillai and N. Ganesan, “Design of simply supported deep beams using IS 456: 2000 and strut and tie method,” Institution of Engineering Journal (India), Part CV, Civil Engineering Division, vol. 88, pp.38-43. 2007. [3] K.N. Smith, and A.S. Vantosiotis, “Shear strength of deep beam,” ACI-Structural Journal, Vol.79, No.3, pp. 429-437, 1982. [4] F. K. Kong, “Reinforced concrete deep beams,” Taylor and Francis Book, Inc, Van No strand Reinhold, New York, 299 pp. 2002. [5] D. H. Sanders, “Verification and implementation of strut-and-tie model in LRFD bridge design specifications,” AASHTO, Highway Subcommittee on Bridge and Structures. 2007. [6] G. Aguilar, A.B. Matamoros, G. Parra-Montesinos, Ramírez, J.A. and Wight, J.K., “Experimental evaluation of design procedures for shear strength of deep reinforced concrete beam,” American, Concrete Institute. 2002. [7] J.W. Park, and D. Kuchma, “Strut - and - tie model analysis for strength prediction of deep beams,” ACI Structural Journal, 104, 6, p.657. 2007. [8] K.H. Yang, and A. F. Ashour, “Strut and tie-model based on cracks_band_theory for deep beam,” Journal of Structural Engineering, 137, 10, pp.1030-1038, 2010.
[9] N. A. J. Al-Bayati, “Behavior of porcelanites reinforced concrete deep beams,” (Ph.D. Thesis), Building and Construction Department, University of Technology, Baghdad, Iraq, 298 pp. 2012. [10] IQS No. “Portland cement,” Central Agency for Standardization and Quality Control, Planning Council, Baghdad, IRAQ, (in Arabic). 5/1984. [11] IQS No. “Aggregate from natural sources for concrete,” Central Agency for Standardization and Quality Control, Planning Council, Baghdad, IRAQ. 45/1984.
[12] ASTM-A370-14, “Standard test methods and definitions for mechanical testing of steel products,” ASTM International, West Conshohocken,” PA, 2014.
[13] ASTM A615/A615M − 15, “Standard specification for deformed and plain carbon-steel bars for concrete reinforcement,” Vol. 01.04, 2015.
[14] ASTM C39/C39M-03, “Standard test method for compressive strength of cylindrical concrete specimens,” ASTM International, West Conshohocken, PA, 2003.
[15] ASTM C496/C496M -11, “Standard test method for splitting tensile strength of cylindrical concrete specimens,” ASTM International, West Conshohocken, PA, 2011.