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.

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.

The evolution of a new application for the use of fiber-reinforced polymer (FRP) formwork is described from its inception, through research and to actual implementation in a construction project. FRP formwork is becoming an attractive alternative to traditional wood forms in concrete floor construction and particularly for highway bridge decks. The recent development of new wide flange or bulb tee precast concrete bridge girders has resulted in short spans between girder flanges that need to be filled by formwork before the deck can be cast. FRP planks are an ideal solution for spanning this short gap and may be left as stay-in-place (SIP) forms. A commercial pultruded FRP floor plank was adopted for use as SIP forming for bridge decks. Rather than being used as intended, however, the plank is turned upside down before the concrete is placed and becomes bonded to the concrete. The testing of this SIP formwork system to prove its capacity in resisting static and impact loads during construction, its contribution to crack control in concrete under flexural loading, and its bond characteristics with a concrete deck are described. The results of the bond tests are used to create a "bond element" that could be used to predict the flexural behavior of concrete members with the FRP SIP formwork. A case study of construction of a highway bridge deck on U.S. Highway 12 with the new forming system is detailed after the FRP form capacities were proven through load testing. The advantages of using FRP planks for bridge deck construction are discussed and compared with traditional construction using wood forming that is subsequently removed.

This paper presents an analytical procedure for modeling concrete-filled fiber-reinforced polymer (FRP) tubes (CFFTs) subjected to reversed cyclic bending, including a method for predicting their fatigue life. The model employs procedures to account for creep and stiffness degradation of FRP and concrete. The predicted behavior compared reasonably well with experimental results of three large-scale CFFT specimens tested under reversed high-cycle fatigue. It was shown that excessive slip between the concrete core and FRP tube reduces fatigue life and, hence, the accuracy of prediction was better at lower moments as slip was less. A parametric study conducted showed that time-dependant properties of concrete and FRP affect the long-term deflection of CFFTs subjected to reversed cyclic bending. Increasing the loading frequency, for the same number of cycles, decreases the deterioration in the response in terms of excessive deflection. Finally, CFFT members with a larger diameter-to-thickness (D/t) ratio (that is, smaller FRP reinforcement ratio) suffer a slightly larger deterioration in their cyclic response than CFFTs with smaller D/t ratio.

An investigation of a structural fiber-reinforced polymer (FRP) stay-in-place (SIP) form used to construct and reinforce a deck for a prototype military bridge system is discussed. The FRP SIP form is supported by a deployable truss and the bridge is completed with a cast-in-place deck. A unique feature is that the fiber-reinforced concrete deck also acts as the upper chord of a truss for the bridge-subjecting it to combined bending and longitudinal axial load. An experimental program investigated the behavior and capacity of the fiber-reinforced concrete deck. Specimens spanning 1.83 m (6.00 ft) with simple supports and 3.66 m (12.0 ft) with an intermediate support were tested. The results were statistically analyzed and compared to the ACI 440.1R design guide. The results showed that flexural and flexural-shear capacities were accurately predicted, provided that the eccentricity, due to the combined loads, was accounted for in the calculations.