Earthquake design and analysis of Tall RC Chimney by John L. Wilson [Thesis]

Design and Evaluation of Jointed Plain Concrete Pavement with Fiber Reinforced Polymer Dowels

This study evaluates fiber reinforced polymer (FRP) dowel bars as load transferring devices in jointed plain concrete pavement (JPCP) under HS25 static and fatigue loads and compares their response with JPCP consisting of steel dowels. Along with laboratory and field evaluations of JPCP with FRP and steel dowels, analytical modeling of dowel response was carried out in terms of maximum bending deflection, relative deflection (RD), and bearing stress of dowels. In addition, field rehabilitation of JPCP was carried out using FRP dowels to evaluate its long-term performance. Laboratory tests included static and fatigue load application corresponding to HS25 load and 1.5 times HS25 load on concrete slabs (27.94- and 30.48-cm (11- and 12-inch) depth) with 3.81- and 2.54-cm (1.5- and 1.0-inch) steel and FRP dowels at different spacings (30.48 and 15.24 cm (12 and 6 inches)). Both 3.81- and 2.54-cm (1.5- and 1.0-inch)-diameter FRP dowels were installed in the field with 15.24-, 20.32-, 22.86-, and 30.48-cm (6-, 8-, 9-, and 12-inch) spacings. Load calibrated field tests were conducted on these pavements using a West Virginia Department of Transportation truck in 2002 and 2003. FRP dowel bars that were 1.5 inches in diameter were also used for pavement rehabilitation. Field data collected through an automatic data acquisition system included strain and joint deflections, which were used for assessing joint load transfer efficiency (LTE), joint RD, and pavement performance. Theoretical calculations are provided through different examples for JPCP with FRP and steel dowels by varying dowel diameters, spacing, dowel material properties, joint width, and base material properties. This research showed that JPCP with FRP dowels provided very good LTE up to and beyond 90 percent, which exceeds the American Association of State Highway and Transportation Officials and American Concrete Pavement Association criteria. JPCP with FRP dowels also provided sufficient LTE after 5 million cycles of fatigue tests under HS25 loading.

Design of Continuously Reinforced Concrete Pavements Using Glass Fiber Reinforced Polymer Rebars

This is Task 3: Continuously Reinforced Concrete Pavement. The corrosion resistance characteristics of glass fiber reinforced polymer (GFRP) rebars make them a promising substitute for conventional steel reinforcing rebars in continuously reinforced concrete pavements (CRCPs). Studies are conducted on the effect of using GFRP rebars as reinforcement in CRCP on concrete stress development, which is directly related to the concrete crack formation that is inevitable in CRCP. Under restrained conditions, concrete volume change because of shrinkage and temperature variations is known to cause early- age cracks in CRCP. In this study, an analytical model has been developed to simulate the shrinkage and thermal stress distributions in concrete due to the restraint provided by GFRP rebars in comparison with the stresses induced by steel rebars. The results show that the stress level in concrete is reduced with GFRP rebars because of a low Young’s modulus of GFRP. In addition, the analytical model has been used to estimate concrete strain variation in reinforced concrete slabs because of changes in concrete volume, and the results were compared with the experimental observation. Finite element (FE) methods are also developed to predict the stress distribution and crack width in the GFRP-reinforced CRCP section that is subjected to the concrete volume changes under various CRCP design considerations, such as the coefficient of thermal expansion (CTE) of concrete, the friction from the pavement's subbase, and the bond-slip between concrete and reinforcement. Based on the results from the FE simulation along with the mechanistic analysis, a series of feasible designs of the GFRP-reinforced CRCP is proposed. The stress levels in the GFRP reinforcement, the crack widths, and the crack spacings of the proposed pavements are shown to be within the allowable design requirements.