developing composite action in existing non-composite steel girder ...

connectors. All specimens were an 11.6-m long simply supported beam, with a concentratedload applied at midspan. For all specimens, the steel beam was a W30x99 section of ASTMA922 steel. The reinforced concrete slab was 2130-mm wide and 178-mm thick, with a specifiedconcrete compressive strength of 20.7 MPa. Details are shown in Fig. 3.Figure 4 shows the computed load-carrying capacity of the test specimens with respect to theshear connection ratio from simple plastic analysis. These beam strength values werecalculated using the minimum specified concrete strength ( f 'c= 20.7 MPa) and the minimumspecified yield stress of the steel ( Fy= 345 MPa). The contribution of the longitudinalreinforcing bars was neglected in the strength calculation. The minimum specified tensilestrength of ASTM 193 B7 threaded rod for the DBLNB and HASSAA connectors and ASTMA325 high-strength bolt for the HTFGB connectors is 862 MPa and 827 MPa, respectively.Based on these calculations, the non-composite beam has a capacity of 609 kN. As shown inFig. 4, adding shear connectors significantly increases the computed load capacity of this beam,even with low values of shear connection ratio. Based on this analysis, it was decided to designthe four partially composite beam specimens with a 30-percent shear connection ratio, resultingin a predicted increase of 48 percent in load-carrying capacity compared to the non-compositebeam. To achieve a 30-percent shear connection ratio requires 16 shear connectors for eachshear span (a total of 32 shear connectors for a beam). The shear connectors were 22 mm (7/8in.) in diameter, and their static strength was predicted using Eq. 3.The specimen designations used below begin with the connection method, followed by theshear connection ratio in percentage. “BS” stands for Beam Static test.1782134305 #5 & #4 @152#4@305Load (kips)12001000800901 kN1048 kNW30x99Unit: mm600609 kN 30%0 0.2 0.4 0.6 0.8 1Shear connection ratio (N/N f )Figure 3 – Details of specimen cross sectionFigure 4 – Predicted load capacity of testspecimens versus shear connectionMaterial propertiesMechanical properties of structural components used in the test specimens are shown in Table1. Concrete for the specimens was delivered by ready-mix truck. The specified compressivestrength was 20.7 MPa with 19-mm river aggregate. Five Star ® Highway Patch, a fast-settinghigh-strength grout, was used to fill the hole in the concrete slab after installation of the DBLNBand HTFGB connectors. Hilti HY 150 adhesive was used for the HASAA connectors.The steel beams used for the full-scale beam tests were of ASTM A992, which has a minimumspecified yield stress of 345 MPa. Steel coupons were taken from both the beam web and theflange. The Grade 60, #4 longitudinal reinforcing bars used in the specimens were also tested intension to evaluate mechanical properties. The ultimate tensile strength of the ASTM A193 B7