International Concrete Abstracts Portal

With traffic volumes continuing to increase on a rapidly deteriorating infrastructure, new methods are needed for expediting construction of durable, high performance concrete pavements with minimal disruption to traffic. One method, which has received significant attention in recent years, involves the use of precast concrete panels. Precast concrete panels can be cast and cured in a controlled environment, stockpiled, and set in place in a short amount of time, allowing for construction to take place during overnight or weekend operations. In March 2000, the Center for Transportation Research at The University of Texas at Austin completed a feasibility study which investigated the use ofprecast prestressed concrete panels for pavement construction. Following the feasibility study, a pilot project was initiated by the Texas Department of Transportation to test and refine these concepts on an actual project. Recently, consbuction of this pilot project was completed on a section of frontage road along northbound Interstate 35 near Georgetown, Texas. Although it was constructed without the time constraints and complexities that will eventually need to be considered for precast pavement construction, the viability of the concept for precast prestressed concrete pavement was clearly demonstrated and will ultimately lead to development of future precast prestressed concrete pavements.

This Symposium Publication is a compilation of 13 papers presented at a sympsoium held at the 2002 ACI Spring Convention in Detroit honoring Richard W. Furlong. Topics include high-strength high-performance concrete columns and biaxial bending, the rold of FRP reinforcement and strut-and-tie models, the use of precast prestressed concrete in building and highway pavements, composite steel-concrete construction, and the teaching of structural concrete design. 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. SP213

This paper provides discussion and suggestions on the very difficult question of how to best teach the design and construction of concrete structures at the undergraduate level and beyond. The end goal remains unchanged-to provide the best possible constructed facilities for the public and private sectors. After presenting the background and scope of coverage, important issues in structural design are discussed, including a defmition of the three types of knowledge bases needed in performing any design. Expectations of new graduates as they enter the work force are covered, and implications for professional registration are discussed. The paper continues with extended discussion on a host of important issues that need coverage to varying degrees in the curriculum. The critical importance of proper integration of materials selection into the overall design process is explored. Given that learning must be a life-long process, professional post-B.S. education approaches (both "conventional" and internet-based) are presented, along with comments on the ASCE position that the professional Master’s degrees should become the degree of entry into the profession. The paper concludes with suggestions and recommendations.

A finite element analysis of strength determined from 150 physical tests of rectangular composite steel-concrete columns taken from the published literature was undertaken. The columns used for this study were braced and pin-ended and were constructed using normal strength concrete with a specified compressive strength between approximately 2500 and 8100 psi (17.2 and 55.8 MPa). The columns were subjected to short-term loads producing pure axial force, combined axial force and symmetrical single curvature bending, or pure bending. Major variables included the concrete strength, the end eccentricity ratio, the slenderness ratio, the structural steel index, and the tie/hoop volumetric ratio. The study provides a critical review of the reliability of the finite element modeling method examined.

The amount of tension reinforcing steel bars plays a major role in determining the flexural ductility of reinforced concrete beams. The addition of Carbon Fiber Reinforced Polymer (CFRP) composites, which is another form of tension reinforcement, affects the ductility of concrete beams strengthened with CFRP sheets. Several researches have'investigated the use of CFRP for increasing the flexural strength of concrete beams. However, the flexural ductility of beams with respect to the amount and yield strength of existing ordinary steel bars has not been investigated in depth. In addition, delamination of CFRP sheets dominates the ultimate mode of failure of flexural members strengthened with CFRP sheets, which limits the ductility of strengthened members. There is a need to investigate the effect of CFRP anchorage system on the overall ductility of strengthened girders. This paper presents the results of an experimental investigation of nine large-scale reinforced concrete beams strengthened with CFRP composite sheets. The main variables are the amount of the existing reinforcing steel bars, yield strength of steel bars, and the type of CFRP anchorage. The amount (size and type) of the longitudinal CFRP sheets was maintained constant. Test results showed that the lower the amount of existing ordinary steel bars the lower the flexural ductility of the CFRP strengthened beams. Test results have also shown that CFRP anchorage could significantly increase the flexural ductility of CFRP strengthened beams. Such important findings should be reflected on the design equations of CFRP sheets required for strengthening existing reinforced concrete beams to ensure an acceptable level of flexural ductility.