3 Master of the Department of Civil Engineering, NTUT, Taipei, Taiwan. The Research of the Mechanical Behavior of the Combined FRP Beam-Deck System Yeou-Fong Li1, Tseng-Hsing Hsu2 and Yu-ying Lin3 1Professor of the Department of Civil Engineering , NTUT, Taipei, Taiwan. 2Professor of the Department of Civil Engineering, CHU, Hsinchu, Taiwan. 3 Master of the Department of Civil Engineering, NTUT, Taipei, Taiwan. Abstract : This study focused to Glass Fiber Reinforced Polymers (GFRP) composite material members with different types of section combination in order to improve the stiffness of a single component. In response to design requirements, the appropriate GFRP section was selected with reference to the actual scale of the GRFP beam-deck system. This paper uses different beam sections which are bonded together with a GFRP plate to conduct a three-point bending test. According to test results, the ultimate strength, stiffness and failure mode of the combined component is enhanced when compared to the single component. Finally, the Finite Element Method (FEM) numerical simulation of the combined GFRP beam-deck system was done with ANSYS before comparing the experimental result with the analytical result and thus, verifying the accuracy of the FEM model. Through scaled experiments and analysis conducted to investigate the failure mode, the combined GFRP beam-deck system had achieved the optimum safety requirements of its connected members and proves to have a good economic. Keywords： FRP; Combined component; Beam-deck system; Three-point bending test; Failure mode The three-point bending tests of a FRP beam and beam-deck system Experimental results result of combined GFRP beam-deck system Type Pmax (kN) δmax (cm) K (kN/cm) Weight (kg) NTD. Failure mode BBP 45.91 0.737 67.91 4.05 765 A BRP 49.04 0.763 70.19 5 909 BREP 101.55 1.27 110.76 9.76 1,149 S1 21.98 1.55 14.64 2.61 423 A：crushed at the loading side Experimental results result of combined GFRP beam Type Pmax (kN) δmax (cm) K=P/δ (kN/cm) Weight (kg) NTD. Failure mode BP 45.91 0.737 67.91 4.05 765 A BR 49.04 0.763 70.19 5 909 BRE 101.55 1.27 110.76 9.76 1,149 S1 21.98 1.55 14.64 2.61 423 S2C1 25.69 0.501 53.03 6.07 940 S2C2 24.25 2.610 9.97 12.14 1,880 S4C1 74.39 0.839 95.28 11.47 S4C2 53.66 2.81 19.85 22.94 3,760 A：crushed at the loading side Comparing the P-δ relationships of combined GFRP beam-deck system Conclusions The use of combined beam members, increasing the moment of inertia of the beam members, among the components of mutual cementation good bending performance of the composite beam components effectively, can improve the stiffness of the single beam members and enhance the stiffness and strength. Selection of appropriate combinations of beam members section, play a combination of the characteristics of the beam members, the combined beam - the version of the system test, system type can effectively provide overall strength and stiffness, due to the different characteristics of the direction of the beam and the version of the component fibers, the deck version placed on completely passed to the beam members to the beam component uniform force. Comparing the P-δ relationships of combined GFRP beam