International Concrete Abstracts Portal

This paper presents the seismic behavior of two large-scale hollow-core fiber-reinforced polymer-concrete-steel (HC-FCS) precast columns having two different footing connections. The precast HC-FCS column consists of a concrete shell sandwiched between an outer fiber-reinforced polymer (FRP) tube and an inner steel tube. The steel tube was embedded 635 mm (25 inches) into a reinforced concrete footing, while the outer FRP tube confined the concrete shell only i.e. it was truncated at the top surface of the footing. One connection included embedding the steel tube into the footing. The other one included using a corrugated steel pipe (CSP) embedded into the concrete footing outside the steel tube to achieve better confinement. This study showed that the connection including the CSP is deemed satisfactory and was able to develop the plastic flexural capacity of the HC-FCS column providing good ductility and energy dissipation compared with the other connection type.

Since the late 1980s, FRP products have seen increased use in repair and strengthening of concrete structures. The traditional technique is referred to as wet layup where carbon or glass fabric are saturated with epoxy in the field and applied to the structure. In this paper I present several new products that I have developed in recent years. One is very large pre-cured carbon or glass laminate sheets that can be used to repair columns, piles underwater, pipelines, etc. The other is a honeycomb-FRP combination that allows construction of lightweight stiff elements. This product can be used to build pipes that can serve as free-standing elements or in slip-lining repair of deteriorated culverts and pipes. These products can also be used as stay-in-place forms for repair of seawalls, large piers and the like. Examples of field applications are also presented.

To prevent future blowouts of sections of the 50-year-old pipe, the Providence Water Supply Board decided to evaluate the condition of a main water pipeline. Non-destructive testing (NDT) investigations revealed that certain sections of the pipe were potentially deficient due to corrosion and breakage of the prestressing system. Strengthening of deficient sections was necessary to maintain the pipeline operational. A carbon fiber in-situ lining appeared to be the fastest, least disruptive, and most cost-effective upgrade solution. The specialty concrete repair contractor conducted full-scale tests to validate optimum FRP repair and waterstop termination design. In these tests, after the carbon fiber liner was installed, the prestressing strands of the FRPstrengthened section were cut leaving the FRP to be the only reinforcement. The test pipe was progressively pressurized until failure occurred at approximately 2-1/2 times the pipe service and surge pressures. The full-scale test proved the integrity of the system beyond theoretical prediction and assured the owner that strength was added to the pipe sections. The lightweight, flexible carbon fiber material along with thorough planning helped overcome challenging working conditions and provided a fast and effective upgrade solution.

Important and often overlooked parts of any building or structure are the systems located behind the walls, under the floors, and in the ceilings of these structures. Installed when the framework of a building is just taking shape, these systems provide the occupants of the building with potable water and remove the waste water safely, quietly, and efficiently. Because these systems are installed within walls, floors, and ceilings, the reliability and longevity of the systems must be equal to the expected life of the building. Two such systems are the sanitary and stormwater piping systems found in all buildings. The wastewater system removes wastewater from the bathrooms, kitchens, and restrooms located inside these structures. The stormwater or rainwater systems drain the exposed roofs, patios, and terraces of rainwater, melted snow, and ice. Both systems use cast iron soil pipe, which is joined with varying types of fittings, within the building's structure. Both systems operate in nonpressure applications, using gravity to remove the rainwater and wastewater from the building. A necessary part of these piping systems is a reliable, cost efficient method of joining the pipe and fittings. This paper traces the history of cast iron soil pipe and discusses design changes in pipe and fittings and the development of applicable standards.

Reinforced concrete pipe used as sewer pipe is required to have excellent durability, especially chemical resistance, in addition to high strength and good economy. A precast composite pipe, in which a reinforced concrete pipe is lined with polymer mortar as soon as centrifugal compaction and drainage have been completed, was developed and investigated. Chemical resistance of the polymer mortar exposed to acidic and alkaline water was studied first by immersion tests and manufacturing process of the composite pipe was introduced next. Subsequently, load tests were carried out and elastic behavior, cracking, and breakable strength of the pipes were investigated. Finally, a reasonable design method for the composite pipe is discussed and proposed.