Experimental and numerical investigation of bending performance of prestressed purlins having different longitudinal web opening

Abstract

Variable cross-section pre-stressed precast concrete purlin (PPCP) members are frequently used in industrial buildings. Lightening these elements, which create a significant weight on the roof plane, is extremely important to reduce both concrete consumption and the weight that will affect the earthquake force. The voids left in the purlin bodies can make them even more economical. A series of experimental and numeric studies were carried out to find an answer to this research question. In the study, 8 PPCP beams with different 1/1 geometric scale web opening ratios (ranging between 7.5%similar to 35% depending on the beam length) were tested. At the end of the experimental study, the openings created in the beams did not significantly reduce the load carrying capacity. In addition, bearing capacity of the reference beam was obtained approximately 17% greater than the calculated analytical value. The results of the tests were validated utilizing ABAQUS FEM. Then, a parametric study was performed on 48 models according to three different pre-stressing levels (0.3 P, 0.6 P and 0.9 P) and three different concrete strengths (30 MPa, 40 MPa and 50 MPa). According to results, especially in PPCP with web opening ratios of 27.5% and 32.5%, both initial stiffness and ductility values increased compared to the reference beam. From the numerical models, it was revelead that the decrease in concrete strength caused a capacity loss of up to 17%, especially in beams with the highest opening ratio. It was discovered that the increase in the pre-stress level increased the stiffness and capacity, but the least increase was in the beam with the highest opening ratio.