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Precast concrete decks have begun to revolutionize the bridge design industry due to their rapid constructability, reduction in overall mobilization and high quality control. According to international codes it was found that distribution of shear connectors is one of the most important factors that has an effect on the capacity of the connection. Previous research and design guidelines suggest the use of two different approaches to quantify the required interfacial shear strength, namely based on the maximum compressive forces in the flange at mid-span or the maximum shear flow at the supports. The research objectives can be summarized in evaluating the structural behavior and load carrying capacity experimentally and analytically for precast girders and precast slabs connected through shear connectors in grouting pockets in the case of regular or concentrated shear connectors distribution at support. In addition the effect of adding horizontal rebars around the grouting pockets in the deck slab was determined. Seven composite RC T-beams with 2.00 m span were tested under static loading conditions. INTRODUCTION Several precast elements are available to meet with all construction requirements. It is often preferable to transport beams and deck slabs separately to reduce the weight of each element. The interfacial shear transfer between the top slab and the supporting beams is of great significance to the overall deck load carrying capacity and performance. To give an understanding of the behavior of precast beam connected to precast panels by using shear connectors a brief review of previous research work can be summarized as follows: 1Mast (1958) Mast (1958) was the first to introduce a linear shear friction equation, and was later revised by Birkeland and Anderson (1960). The equation as introduced by Mast is as follows: vn = ρ.fy . μ (MPa) ( 1 ) Where, vn = ultimate horizontal shear strength, ρfy = clamping stress, μ = empirical coefficient of friction The equation (1) is simple but is very conservative for law clamping stresses and unsafe for high clamping stresses (Loov and Patnaik–1994). EFFECT OF SHEAR CONNECTORS DISTRIBUTION AND REINFORCEMENT LAYOUT AT GROUTING POCKETS ON THE CONNECTION BETWEEN PRE-CAST CONCRETE GIRDERS AND PRE-CAST DECK PANELS" 2Birkeland (1966) Birkeland (1966) was the first to introduce a non-linear function for the ultimate shear capacity of the interface. Birkeland’s equation only incorporated a factor times the clamping stress as shown below: vn=2.78 √( ρv fy) (MPa) ( 2 ) Nothing in Birkeland’s equation accounted for varying surface treatments or concrete strengths. 3Shaikh (1978) Shaikh (1978) proposed a modification to the shear-friction provisions of ACI. The proposed equation can be simplified to the following: vu = . ρv.. fy . μe (MPa) ( 3 ) Where, In this simplified equation, 1.0 λ has been substituted for μ and λ is a constant used to account for the effect of concrete density. λ = 1.0 for normal weight concrete, λ = 0.85 for sand-lightweight concrete, λ = 0.75 for all-lightweight concrete, the strength reduction factor for shear was  = 0.85. 4Loov (1978) Loov (1978) was the first to introduce the influence of concrete strength into the horizontal shear strength equation. Below is the equation that was presented by Loov: (MPa) ( 5 ) Where, k = constant (0.5 was suggested for an initially un-cracked interface). f'c = the concrete strength in (MPa). 5Patnaik (2001): Patnaik recommended the use of the following equations. vu = (0.6+ .fy) ≤ 0.2 f'c and 5.5 (MPa) ( 6 ) vu = 0 for  .fy ≤ 0.35 (MPa) ( 7 ) Patnaik states that it is possible to obtain some nominal shear strength from a smooth interface with no reinforcing, but for design this is not recommended. Experimental program The experimental program comprised a total of seven medium-scale reinforced concrete beam specimens tested up to failure at the Reinforced Concrete Laboratory of the Structural Department of the Faculty of Engineering at Ain Shams University. The seven beam specimens were tested to investigate the modes of failure, the ultimate load carrying capacity and the behavior of the connection between pre-cast beams connected to pre-cast deck slab and its influence on the beam action mechanism. The deformation, crack pattern, strain of main reinforcement and strain of shear connectors were monitored and recorded during the tests. All specimens with overall dimensions of 450 mm width, 80 mm thickness for the flange, 150 mm width and 300 mm depth for the web with span 2000 mm. u 2 9 . 6 v e (MPa) ( 4 )

journal of al-azhar university engineering sector

"EFFECT OF SHEAR CONNECTORS DISTRIBUTION AND REINFORCEMENT LAYOUT AT GROUTING POCKETS ON THE CONNECTION BETWEEN PRE-CAST CONCRETE GIRDERS AND PRE-CAST DECK PANELS"