P.V. Vijay’s research while affiliated with West Virginia University and other places

Buildings with historic and cultural significance are part of the national heritage and must be preserved for future generations. Preservation of historic buildings depends upon usage consistent with their structural capacities and regular maintenance. Most of the old and historic buildings built in previous centuries are constructed mainly of masonry, timber, and steel. These materials have different mechanical properties and fire-resistance capabilities. Fires can cause significant nonstructural or structural damage within a matter of minutes or hours. An overview of the fire-related damages in both old or historic buildings with respect to the types of materials, causes of fire, history of fire accidents, fire safety codes, and fire protection measures along with visual evaluation details of fire-affected historic buildings that were built nearly 200 years ago in Harpers Ferry, WV are presented and discussed.

Prefabricated fiber-reinforced polymer (FRP) repair systems are becoming popular for structural repair because FRPs superior resistance to corrosion and weathering. Several parameters impact the effectiveness of this type of repair, including the structural continuity provided by the joining system and grout properties. This study numerically investigated the effects of these critical design parameters to generate new knowledge and understand fundamental structural behaviour of a prefabricated composite repair system. The results reveal that the effective transverse tensile strength of FRP joint should be as low as 20% of the jacket strength for structural repairs. Moreover, grout stiffness dictated the stress transfer between the core and outer jacket. Increasing the compressive strength of the grout delayed grout cracking and degradation, accompanied by a rapid increase in FRP joint strain. Lastly, numerical simulation of a corroded steel column in an actual bridge shows that the application of the FRP jacket improves the strength capacity by 320%, which is 85% higher than that of the conventional FRP repair system. This study provides useful information for optimally designing and effectively using prefabricated composite jackets for structural repairs.

When used as an internal reinforcement, fiber-reinforced-polymer (FRP) composite bars are exposed to a highly alkaline (pH > 12.5) concrete environment. This study evaluated the durability of 24 types of FRP bars in a simulated alkaline concrete environment, specifically with respect to reinforcing-fiber type (carbon, basalt, and glass), fiber sizing, resin chemistry, and manufacturer. A total of 10 types of glass fibers, including two types of E-glass fibers and eight types of electrical corrosion resistance (ECR)-glass fibers, four types of basalt fibers, two types of carbon fibers, six types of resin systems based on vinyl ester, polyurethane, and epoxy resins, and five types of proprietary fiber sizings were used in manufacturing the bars. The study focused on assessing the tensile, transverse-shear, and interlaminar-shear properties of FRP bars subjected to 3 months of accelerated alkaline conditioning at 60°C, as per Canadian Standards Association (CSA) and American Society for Testing and Materials (ASTM) standards. The strength retention and failure of these bars were evaluated as a measurement of the durability and long-term performance of the FRP bars currently available on the market and for quality control by manufacturers. Statistical analysis using independent samples t-test and one-way analysis of variance revealed that the manufacturing parameters have a significant effect on the mechanical characteristics and alkaline resistance of FRP bars. In particular, the results show that the FRP bars manufactured with the same parameters and fiber types but by different fiber manufacturers with different fiber sizings and resin systems produced bars with totally different strength properties and durability performance in an alkaline environment. Vinyl ester resin and silane-sized fiber was the most compatible resin system and produced a more durable glass-FRP bar, while the epoxy resin yielded more durable basalt- and carbon-FRP bars. This paper also describes a procedure for and a criterion of the optimum manufacturing parameters to achieve specific mechanical properties and durability performance with FRP bars.

Fibre reinforced polymer (FRP) composites have attracted significant attention in repairing existing and deteriorating structures since the traditional rehabilitation techniques have several limitations in terms of durability, self-weight and complex installation process. Prefabricated FRP composite jackets are the preferred solution in repairing bridge piles located both underwater and above the waterline as they can be easily placed around the damaged pile to form a robust single-piece repair system. The structural continuity of the jacket in such a repair system is critical for effectively utilising its maximum strength. This study presents an extensive review of the current practices and new opportunities for using prefabricated composite jackets for structural repair. Important design considerations to effectively utilise prefabricated FRP composite jackets in repairing structures are presented and analysed. The review also identifies the challenges and highlights the future directions of research to increase the acceptance and use of emerging composite repair systems.

Fibre reinforced polymer (FRP) composite jackets have become a popular option for repairing deteriorated structures due to the superior characteristics of composite materials in resisting corrosion and in providing a high strength but lightweight repair system. Recently, a novel prefabricated FRP composite jacket with an easy-fit and self-locking mechanical joining system was developed. This paper presents the experimental and numerical studies on the effectiveness of the FRP jacket in repairing reinforced concrete (RC) columns with simulated corrosion damage under uniaxial compressive loading. The experimental results showed that the jacket successfully stabilised and restored the axial strength capacity of the damaged concrete columns. Moreover, the results of the finite element (FE) analysis revealed that the joint of the jacket should be placed away from the damaged zone to minimise stress concentration and to effectively utilise the jacket as a repair system. Finally, a joint strength of at least 20% of the hoop tensile strength of the jacket is effective in repairing damaged structures.

There is an increased demand for abrasive wear-resistant coatings that add durability to steel hydraulic structures, particularly for those subjected to flowing water with debris and alternate wet/dry cycles. These coating systems provide not only corrosion and chemical resistance, but also good erosion and abrasion resistance to the metallic surfaces, which are constantly exposed to flowing water containing sand particles and debris. Generally, vinyl-based coatings are used on hydraulic steel structures to protect them from corrosion and abrasion. However, due to the existence of high water force and debris, the coating is abraded at a faster rate leading to significant maintenance and repair costs. In this study, abrasive wear resistance of conventional vinyl-based coating systems currently used on lock and dam steel structures by U.S. Army Corps of Engineers has been compared with polymer matrix composite coatings, fibrous polymer coatings, and ultrahigh molecular weight polyethylene (UHMWPE). Six coating systems were evaluated through two-body abrasion tests using a reciprocating abrader under dry and wet conditions. Furthermore, wettability of the coating systems and its effect on the wear rate under the presence of water was studied. In addition, scanning electron microscopy of the wear tracks on different coatings was conducted to study and identify their failure mechanisms. Based on the results, UHMWPE and polymer–ceramic composite coatings were found to perform significantly better than the conventional vinyl-based coatings.

This study evaluates the effectiveness of a novel composite repair system consisting of prefabricated fibre reinforced polymer (FRP) jacket with joint and grout infill for damaged concrete structures subject to flexural loads. Full-scale beams were prepared and tested under four-point static loads to evaluate the effects of damage location in the concrete member, joint location and internal surface coating of the jacket. The results showed that the behaviour of the repaired system is governed by the tensile cracking of the grout and failing of teeth at the joint. The FRP jacket is found to be more effective in repairing concrete members under flexural load when the damage is located at the top than at the bottom of the member. This effectiveness can be further increased by placing the joint of the composite jacket away from the compression zone. Moreover, the provision of epoxy and coarse aggregates inside the jacket surface resulted in better stress distribution and cracks propagation in the grout than the one without. Finally, a simplified fibre model analysis which considers the confined tensile and compressive properties of the grout reliably predicted the flexural capacity of the damaged beams repaired with the FRP jacket.

Jacketing using prefabricated fiber reinforced polymer (FRP) composite shells is an attractive repair system for deteriorating structures exposed to the marine environment. However, most available techniques lack an effective joining system capable of providing structural continuity along the hoop direction. This paper addresses the evaluation of the efficiency of a FRP jacket with an innovative joining system and the behavior of damaged concrete columns repaired with jackets considering several parameters, that is, level of steel corrosion, level of concrete cover damage, and the shape effect. The results showed that the jacket restored the load-carrying capacity by 99% and 95% for columns with 25% and 50% corrosion damage, respectively. Moreover, the jacket effectively restored the axial load capacity of columns with 50% and 100% concrete cover damage by 95% and 82%, respectively. The proposed system was more effective in circular columns because the axial load capacity of the repaired columns was 43% higher than the square columns. A theoretical analysis of the axial load capacity of the repaired columns indicated an excellent agreement with the experimental results.

This work focused on the structural condition assessment, repair, and rehabilitation aspects of old buildings built primarily with masonry and timber. Specifically, several school buildings that are old and considered historically important in the regional education landscape were considered for evaluation. Several visual and nondestructive load-testing techniques were used to evaluate the structural condition, stresses and deformations, structural and nonstructural issues, and building safety. Cost-effective designs were implemented to repair and rehabilitate damaged structural members with locally available materials that matched the visual needs while meeting the design requirements. Evaluations of buildings focused on masonry foundations and walls, wood floor joists and roof rafters, steel beams and truss members, and other structural elements. Energy losses were evaluated through infrared (IR) thermography techniques. After approximately a century of service, most of the building elements were found to have the required design strength and meet the serviceability criteria.