مقاومت خمشی تیرآهن جوش خورده بتن پیش ساخته با استفاده از بتن پودر واکنشی Improvement of Flexural Strength of Precast Concrete Spliced Girder Using Reactive Powder Concrete in Splice Region

1. INTRODUCTION: It is widely known that the precast concrete girder bridges have taken a great interest in the recent three decades due to the high quality, high strength, and economical cost to produce a very long girders that difficult of transportation as a one unit. As a solution for this problem and to accelerate the construction of bridges taking into account the cost, spliced precast concrete girder bridges has been produced [1].The splicing technique of concrete girder has provide significantly increasing in span ranges of precast concrete girders. It has also used for reducing the number of interior supports which be consider as an obstacle for navigation where this method is less expensive than other alternatives for this purpose. Typically spliced girders has consisted of two or more segments connected to each other at short splice region and casted in place at the site of project to obtain the total length of the girder that has been required. There are limited studies had been carried out about the experimental tests on the spliced girders. In 1993 Garcia [2] described the implementation of a continuous posttensioned bulb-tee girder system in Florida. The test was conducted prior to the full production of the bulb-tee girder system for the Eau Gallie Bridge near Melbourne, Florida. The specimen consisted of two (145 ft) length girders spliced together at an intermediate support. Failure of the specimen was governed by flexure at the intermediate support. The specimen exhibited highly ductile behavior of the post-tensioned bulb tee girder system and a capacity significantly greater than the design loads. Holombo, Priestley, and Seile in 2000 [3] described the overall behavior of precast prestressed spliced girders with superstructure column continuity. The primary objective of this study was focused on the behavior of splices between the girder and the bentcap under seismic load. The experimental work was applied on two 40 percent scale model bridge structure. These girders were spliced with posttensioned strand through the supporting bent. The two model of bridge superstructure displayed ductile behavior under the force, and the displacement exceeded the seismic requirements. The superstructure exhibited mainly elastic response throughout the tests with development of minored cracks. In (2008) Al-Mamuree [4] presented experimental and analytical investigation on pre-stressed concrete girders with field splice. The experimental and theoretical variables were types of support and load, splice location, amount of the area of pretensioned reinforcement, the effect of posttensioning reinforcement, and whether the girder has pre-stressed or not. The test implemented on sixteen rectangular section of concrete girders, eight of them were spliced girders and the other were without splices as a reference for comparison purposes. The tested girders were of different lengths, supports location, and splicing locations. Each of the spliced girders consisted of three segments. Hooked dowels were used for splicing method, and temporary supports were sitting down the spliced regions. The applied load was either concentrated or distributed, the deflection and strain were measured at mid span of the girder.