OPTIMUM PRESTRESSING AMOUNT AND ITS EFFECTIVE FORCE ON PRESTRESSED CONCRETE DOUBLE TEE BEAM WITH WEB OPENING

Double tees shows it's an excellent choice for parking decks and used in roof applications where a long, clear span is required such as gyms and pools. Spans up to 22m can be achieved using Precast Double Tees. Double Tees are pre-fabricated members on plants, which provides excellent quality control and speeds up the construction process. Double tee slabs can be used for most applications requiring a long span floor or roof system (10 m to +30 m) and/or additional load carrying capability. More than that, Double tee slabs prove it has a good resistant to moisture and corrosion. Parking garages, commercial buildings , office buildings, pool roofs ,gymnasiums, food processing plants, industrial buildings, paper mills, and water and sewage treatment plants are all ideal applications. One or both ends of the slabs can be cantilevered at for up to four times the slab depth. Double tee slabs are prestressed. Which will increase the ability to carry heavy loads with allows for longer spans, shallow depth. Further its permits better space planning and a lower floor/floor height. Lengthening the span may be economical (fewer s labs to make and install). Maximum span/depth ratios of forty almost be recommended for floors. Double-tees regularly be used for many types of buildings structures. They are easily shipped and erected, very economical, readily available, and contribute to early building occupancy. Within three phase of study, started by prediction a powerful tool to simulate the full behavior of prestressed concrete double tee beams with web openings under flexure, and continue on its second phase by considering the effect of increasing concrete compressive strength on the obtaining long span length, to this research study (3rd phase) where the an optimization process carried out to check the effect of varying the prestressing tendon value and its effective applied force. The effect of increasing the prestressing force was clearly shown at plastic regain its start effect the performance. Improving behaviour with higher moment capacity is the general view of all tested samples reached 50%-78% comparing to the control beam without web opening. While for varying the value of prestressing tendons, the beams with webopening shows a reduction on its ultimate moments by 61%, 65%, and 61.5% for reducing two tendons, while its show improvement reach 16%, 33%, and 34% when increasing two tendons. 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