International Concrete Abstracts Portal

This Symposiuml Publication includes 48 papers from the ACI Fifth International Confrence on Innovation in Design with Emphasis on Seismic, Wind, and Environmental Loading, Quality Control, and Innovation in Materials/ Hot-Weather Concreting, held in December 2002 in Cancun, Mexico. Topics include the behavior of flared-column bents under seismic loading, marine exposure of high-strength light-weight concrete, and seismic strengthening of a nonductile concrete frame building. Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP209

Test results of four composite RCS beam-column-slab subassemblies under cyclic loading are presented in this paper. The specimens were designed for beam plastic hinging and controlled joint deformations through the use of a deformation-based design model for RCS connections. Tho types of simple connection details were used in the specimens, one with overlapping U-shaped stirrups passing through the steel beam web, and the other with steel band plates wrapping around the column just above and below the steel bem flanges. The performance of the test specimens was evaluated in terms of load-displacement response, beam rotations, joint deformations and energy dissipation capacity. The accuracy of the deformation-based joint model was also evaluated. Excellent response was observed for all specimens, with large beam rotations, minor to moderate joint damage, and significant energy dissipation capacity, indicating that RCS frame construction is adequate for use in zones of high seismicity. Good agreement was also found between predicted and experimental shear force vs. shear deformation response in RCS connections.

This paper presents a rational approach used for the evaluation of inplace concrete pavement with flexural strength requirements. During the construction of a concrete paving project at McCarran International Airport in Las Vegas, Nevada, data was developed from the testing of over 450 specimens of concrete beams, cylinders, and cores representing samples from nearly 170 locations. Hexural, compressive, and splitting tensile strength testing was performed on these samples obtained from locations where comparison between the different types of strength tests was possible. Relationships between this data were evaluated and a rational approach to the evaluation of in-place concrete for compliance with flexural strength requirements was developed. This approach that begins with trial batch data and includes cast and cored specimen, could be applied to other concrete paving projects with similar concerns.

An optical fiber monitoring system was designed and built into a three-span high performance concrete highway bridge. The Rio Puerco Bridge, locgted 15 miles west of Albuquerque, is the first bridge to be built using HPC in New Mexico. The bridge has 3 spans with length of 29 to 30 m. It is designed to be simply supported for dead load and continuous for live load. HPC was used for the cast-in-place concrete deck and the prestressed concrete beams. A total of 40 long-gage (2-m long) deformation sensors, along with thermocouples were installed in parallel pairs at the top and bottom flange of the girders. The embedded seams measured temperature and deformations at the supports, at quarter spans and at mid-span. Measurements were collected during: Beam Fabrication (Casting of the beams, Steam curing, Strand release, Storage), Bridge Constructio~ and Service. The data collected was analyzed to calculate the prestress losses in the girders, compare the losses to the predicted losses using available code methods, and get a better understanding of the properties and behavior of high performance concrete. The project is funded by the Federal Highway Administration, the New Mexico State Highway and Transportation Department, and the National Science Foundation.

The benefits derived from the ability of the fibers to control crack propagation have been recognized for many years. In addition, the development of high-perfurmance concretes has enhanced this situation as the increases in strength lead to a more brittle behavior of the material. The introduction of steel-fiber rein- forcement in these concretes is probably the best way to improve the performance of concrete when higher tenacity is required. This paper shows the contribution of fiber reinforcement in both conventional and high-strength concretes exposed to temperatures up to 500°C. Conuutes with diffemnt types and content of fibers are analyzed, mainly regarding the failure mechanism and tenacity. The post-peak behavior under conpressive and flexural loads is studied using a close loop system. NDT was also used to evaluate the damage. The residual mechanical properties of fiber-reinforced concretes qre affected in a similar way thau those corresponding to plain concrete. Nevertheless, it can be seen that the residual parmeters tend to increase as the strength increases when high carbon-steel fibers bstead of low carbon-steel fibers are used, and when fiber reinforcement is introduced.