Aesthetic Concrete Barrier Design (2006)

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70 CHAPTER 8 CONCLUSIONS The objective of this research was to develop engineering design guidelines for aesthetic surface treatments of concrete barriers for safety shape profiles, such as the New Jersey or F-shape barrier profile. The design guidelines were devel- oped through extensive use of finite element simulation, in conjunction with full-scale vehicle crash testing. The New Jersey barrier was used for the development of the preliminary and the final design guidelines. Vehicular impacts with the F-shape barriers are known to result in lower vehicle instabilities when compared with the New Jer- sey barriers. The guidelines developed are, therefore, con- sidered to be applicable to both New Jersey and F-shape con- crete barriers. To develop design guidelines for the application of aesthetic surface treatments on concrete safety shape barriers, a set of preliminary guidelines were initially developed. A parametric study was performed using finite element simulations to estab- lish these preliminary guidelines. Generalized types of surface asperities were defined in terms of various parameters such as the width, depth, and angle of inclination. Parametric finite ele- ment simulations were performed for asperity angles of 30, 45, and 90 degrees, and each simulation was assigned an out- come of “acceptable,” “marginal/unknown,” or “unaccept- able” based on comparison of the internal floorboard energy with the established threshold values. Preliminary guidelines were then developed in terms of asperity depth, width, and angle of inclination based on the combined set of simulation outcomes. Based on these preliminary guidelines, a crash test plan was developed in which the outcome of one test determined the configuration evaluated in a subsequent test. In other words, the test matrix was adjusted as the crash tests were performed, and the results were analyzed in order to maximize the information available for adjusting and finalizing the rela- tionships for asperity depth, width, and angle. A full-scale crash-testing phase was conducted. The OCD measurements from the tests enabled the adjustment of the thresholds for acceptable and unacceptable floorboard internal energy upon which the final design guidelines are based. For review, the guidelines for safety shape concrete barrier aesthetic surface treatments are presented again in Figure 84 (see Figure 85 for English units). For the convenience of use, guidelines developed for safety shape barriers in this research and the guidelines previously developed by the FHWA and Caltrans for stone masonry guardwalls and for single-slope and vertical-face concrete barriers, respectively, have been consolidated into a single, standalone set of guidelines that appears in the appendix. The appendix provides adequate guidelines to assist the designer with all current types of concrete barriers.