| The research work covered in this report included an extensive experimental program, development of a classic solution, and finite element analysis. The main objectives were to evaluate the feasibility of using fiber reinforced plastic composite (FRP), commercially manufactured by pultrusion process, in roadside safety structures and to understand the structural responses of FRP composite box beams subjected to central transverse impact loads.; Experimentally, 12 rectangular coupon specimens made of the FRP composite materials, aluminium, and steel were tested by using a drop-weight impact-testing machine to determine impact energy absorption, ultimate impact strength, and failure modes of the materials. The comparisons on the test results were made to identify the potential of using the FRP composites in the roadside safety structures. In addition, 48 simply supported FRP composite box beams were tested by using the drop-weight testing machine for impact force-time responses and failure modes. The variables included initial impact velocity, striker mass, span length, and wall thickness of the beams. The impact energy levels induced in the tests were 40.9, 81.7, 99.0, and 197.8 N-m. The FRP composite box beams were also tested in flexural static test and the comparisons on the test results with that from the impact tests were made to study the effect of the impact force on the ultimate strength and failure modes. Finally, engineering material properties of the FRP composites were determined from tension test, compression test, flexural test, and interlaminar shear strength test.; Analytically, a classic solution for predicting the impact responses of the simply supported FRP composite box beams was developed based on linear elastic anisotropic thin-walled closed-section beam theory and Lagrange's equation of motion. The major contributions of the solution were to provide an insight into the impact problem and a fast and effective way to predict linear elastic impact responses of the FRP composite box beams. Additionally, finite element analysis of the FRP composite box beams subjected to the impact loads was performed by using a three-dimensional nonlinear dynamic finite element computer program, LS-DYNA3D. The results from the classic solution and finite element analysis were compared to that from the tests. |
