This paper presents the results of a research project aimed at providing standard sized web openings to the popular precast concrete double tee. 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 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. The design of the web openings was based on prior research and a finite element analysis. Opening size and placement and required material strengths were investigated. Also, the effects of using a two-point depression, rather than the standard one-point depression, of the prestressing strands were investigated. Four 45ft (13. 7 m) long single tee specimens (one leg of a double tee) were tested to failure. The test results obtained from this investigation show that the performance of the specimens with web openings was almost identical to that of the specimen without web openings. Based on these tests, design recommendations are made that will allow the addition of web openings to double tees with minimal additional calculation.
