This CD-ROM consists of 11 papers which were presented in two special sessions sponsored by ACI Committee 440 at the ACI Spring Convention in Los Angeles, California, on March 31, 2008. The technical papers presented at the sessions and published in this volume cover both open and closed FRP forms, including bridge decks, concrete-filled tubes, and girders, and address important relevant aspects such as surface preparation, bond aspects, fatigue, constructability, confinement, and field applications.

The State of Wisconsin recently constructed a highway bridge as part of the FHWA Innovative Bridge Research and Deployment Program. The superstructure is composed of precast concrete I-girders acting compositely with the concrete bridge deck that uses a fiber-reinforced polymer stay-in-place (FRP-SIP) formwork system that serves as positive flexural reinforcement. In-place load test strain data are used to compute wheel load distribution widths and estimates for bending moments acting on unit widths of bridge deck. These widths are compared with those computed using the AASHTO-LRFD and AASHTO Standard specifications. The in-place field data indicate that bending moments within the deck system are reasonably close to predictions made using the Standard and LRFD specification bridge deck approximate analysis procedures. The Standard specification estimates for bending moment per unit width of bridge deck were found to be conservative for interior and exterior deck spans. The LRFD specification estimates for strip width resisting wheel loads are also conservative for interior and exterior deck spans when compared to field-measurement-based predictions.

Hybrid FRP concrete steel double-skin tubular columns (DSTCs) are a new form of hybrid columns recently proposed by the second author. The column consists of an outer tube made of fiber-reinforced polymer (FRP) and an inner tube made of steel, with the space between filled with concrete. In this new form of hybrid columns, the three constituent materials are optimally combined to achieve several advantages not available with existing columns. This paper provides a summary of existing research on this new form of structural members, clarifying its structural behavior under axial compression, bending, and combined axial compression and bending. Test results of hybrid DSTCs are presented that demonstrate that they are very ductile under different loading conditions. A finite element (FE) model for its axial compressive behavior is also presented, which was employed in a parametric study leading to a simple stress-strain model for the confined concrete in hybrid DSTCs described in the paper. In addition, a conventional section analysis based on the plane section assumption and the fiber element approach is presented for predicting the behavior of hybrid DSTCs subjected to bending and eccentric compression. A variable confinement model that accounts for the effect of load eccentricity is adopted in this section analysis for the confined concrete, and is recommended for design use.

One of the applications of fiber-reinforced polymers (FRP) in building and bridge construction is stay-in-place formwork. FRP stay-in-place formwork, in the form of preformed tubes, provides easy form assembly protection of steel reinforcement and concrete against corrosion and chemical attacks while also improving the strength and ductility of structural elements in earthquakeresistant construction. Seismic performance of FRP tubes in building and bridge columns has been investigated through tests of large-scale specimens under simulated seismic loading. The experimental program consisted of tests of circular and square columns confined with carbon FRP (CFRP) tubes. The results indicate that the use of CFRP tubes increases column inelastic deformability significantly. Bridge columns under low levels of axial compression exhibit inelastic drift capacities in excess of 4% before failing in flexural tension due to the rupturing of longitudinal reinforcement. Building columns under higher levels of axial compression show drift capacities in excess of 8% when the behavior is governed by confined concrete. These observations and experimental results were used to develop a displacement-based design procedure for concrete confinement for FRP-encased concrete columns. The paper presents an overview of the experimental program and the design approach developed.

A continuing goal for the civil engineering industry is the design of lightweight flexural elements with high capacity and high resistance to corrosion. The behavior of hybrid composite hollow-box beams was investigated experimentally and analytically to determine the feasibility and effectiveness of such structural sections as the main flexural members in bridge construction. The section was composed of a glass fiber-reinforced polymer (GFRP) pultruded hollow section, reinforced with one layer of steel-reinforced polymer (SRP) sheet or two layers of carbon fiber-reinforced polymer (CFRP) sheet bonded to the bottom flange to carry the tensile stresses. A 54 mm (2 1/8 in) thin layer of ultra-high-performance concrete (UHPC) was cast on top of the section to carry the compressive stresses. In addition to the structural contribution of the GFRP, the box section will act as a permanent stay-in-place form for the concrete. All these materials have superior strength and durability compared to conventional construction materials, so they can be used in much smaller dimensions than traditionally. The materials in the section were assembled using different types of epoxy. Ease of construction and minimum production cost were included in the aims for the system being developed.