Experimental Investigation on Precast Reinforced Concrete Beams with Deformed Bars Welded to Steel Plates and Embedded at Support Sections under Transverse Point Loads

Abstract

This paper presents an experimental investigation on precast reinforced concrete beams with connections in the form of deformed bars welded to a steel plate and embedded at the support sections, using a four-point loading test. The objectives are to study the mechanical behaviors, failure modes and effects of the embedded length of the deformed bars on the strength of the beams, and to compare the results with those calculated using the EIT 1008-38 RC beam design equations. The beams have a cross section of 0.175 m in width and 0.35 m in depth, with a span of 4.0 m.  The beam’s connections were made of steel plates with a cross section of 0.25 m in width, 0.15 m in depth, and 0.02 m in thickness, and were welded to DB16 bars with embedded lengths of 500 (reference beam), 1,000 and 1,500 mm. From the experiments, all of the beams exhibited bilinear behaviors. They behaved linearly elastic up to about 80-90 percent of their maximum load-carrying capacity, and then they behaved non-linearly with a rapid increase in deflection until failure. Under service conditions (at a deflection of L/240), the beams with embedded lengths of 1,000 and 1,500 mm had a load-carrying capacity 4.27 to 17.45% higher than that of the reference beams. The failure modes can be separated into two patterns. The beams exhibited vertical cracks in the concrete at the support sections due to the slip of the steel plate, and then they failed either in flexural failure or diagonal shear failure, in accordance with the experimental design. Finally, when comparing the ratios between the linear elastic load-carrying capacity of the beams from the experiments and that from EIT 1008-38’s equations, the ratios are in the range of 1.70 to 2.86, depending on the embedded length of the deformed bars.