Design aids for prestressed concrete double tee beam with web opening associated with the variation of its compressive strength

Abstract

Precast prestressed concrete double tee beams are one of the most popular precast concrete floor framing system, which it’s being from necessity to carry out many researche’s studies to predict a powerful tool to simulate its full behavior. Herein, an investigating studies have been carried out to check the validity of increasing span length by increasing concrete compressive strength with the existence of web opening. The main advantage of these openings is that mechanical equipment can pass through the webs of double tees instead of under them. This reduces the floor-to-floor height and the overall cost of the building. Another advantage is a slight reduction in double tee weight that would improve the demand on the supporting frame both under gravity loading and seismic excitation. All of that advantage will be more benefit with larger span length, that will be limited within the existence of web opening. A numerical model was prepared checked to simulate the nonlinear behavior of prestressed concrete beams under monotonically increasing load. Within such numerical model, tested programs were made to predict longer span in considerable concrete compressive strength, that chosen from practical available values can be achieved in the site. After all of that a design charts were prepared to be a guide tool to engineers when double tee beams with web opening required to cover more span length. Curves are classified and presented considering the most common typical sections of the double tee beams modified to show the flexibility could be obtained when changing concrete compressive strength.