A series of push-out tests of rectangular concrete-filled tubular columns (CFT) was recently conducted. The objective of this research program was to identify the shear transfer mechanisms between the infilled concrete and the steel tube and to determine a method for evaluating the capacity of the steel-concrete interface in a CFT column. The experimental variables investigated were the wall slenderness ratio (b/t) of the steel tube and the use of shear tab connections to apply axial load to the steel tube. The results of this study indicated that three mechanisms are responsible for shear transfer along the steel-concrete interface in a push-out specimen: adhesion of the concrete to the steel surface, friction, and wedging of the concrete core. The role of each mechanism in transferring shear between the concrete and steel in the CFT push-out specimen at various stages of load and slip is discussed. Design guidelines for shear transfer in rectangular CFT columns are presented, including a proposed bond strength equation and a recommended strength reduction factor for bond.

Reinforced concrete buildings with shearwalls are very efficient to resist earthquake disturbances. In general, reinforced concrete frames are governed by flexure and shearwalIs are governed by shear. If a structure includes both frames and shearwalIs, it is generalIy governed by shearwalIs. However, the ductility of ordinary reinforced concrete framed shear walls is very limited. To improve the ductility, this paper describes experiments on framed shearwal I s made of corrugated stee I, and the experimental results are compared with ordinary reinforced concrete frames and shearwalls. It is found that the ductility of framed shearwalls can be greatly improved if the thickness of the corrugated steel wall is appropriate to the surrounding reinforced concrete frame. If the thickness of the corrugated steel wall is too large when compared to the surrounding frame, the ductility will be reduced. It is also shown in this paper that the fiber-reinforced plastic composites can be used to strength the critical sections of the reinforced concrete frames, so that the seismic behavior (including ductility and dissipated energy) is improved.

were used to upgrade reinforced concrete beams, slabs and piles. GFRP shells were also used for pile upgrade. Some of these components were reinforced and prestressed with CFRP rods and tendons. Finally, other composites, such as epoxy coatings for rebars and engineered wood were addressed. Long term Since 1992, the U.S. Navy, Naval Facilities Engineering Service Since 1992, the U.S. Navy, Naval Facilities Engineering Service Center (NFESC), has been involved in the study and use of advanced fiber Center (NFESC), has been involved in the study and use of advanced fiber reinforced plastic (FRP) composites for its waterfront infrastructure applications. reinforced plastic (FRP) composites for its waterfront infrastructure applications. Carbon FRP (CFRP) and glass (GFRP) composites were assessed and Carbon FRP (CFRP) and glass (GFRP) composites were assessed and demonstrated at NFESC and at various sites throughout the Navy. CFRP sheets demonstrated at NFESC and at various sites throughout the Navy. CFRP sheets were used to upgrade reinforced concrete beams, slabs and piles. GFRP shells were also used for pile upgrade. Some of these components were reinforced and prestressed with CFRP rods and tendons. Finally, other composites, such as epoxy coatings for rebars and engineered wood were addressed. Long term durability issues are still being investigated. This paper represents an overview of the assessment and use of FRP materials in Navy reinforced concrete waterfront structures. durability issues are still being investigated. This paper represents an overview of the assessment and use of FRP materials in Navy reinforced concrete waterfront structures.

Using experimental data from previous tests and detailed analytical studies, the applicability of ACI and AISC standard techniques for concrete-filled tubular columns (CFTs) is evaluated. The test specimens include short and slender CFTs made with normal and high strength steel tubes filled with normal and high strength concrete. The focus of this paper is on rectangular and square tubes. To gauge the success of the code-based methods, the capacities are also computed by the fiber analysis techniques, along with a member level iteration algorithm for analyzing members with significant length. The results indicate that the ACI and AISC methods can yield substantially different capacities. In general, the capacities from the ACI method are reasonably close to those obtained from detailed analytical methods so long as normal strength tubes are used. Both the ACI moment magnifier method and AISC method are appropriate for slender CFTs although the ACI method tends to match the analytically calculated capacities more closely. Neither the ACI nor AISC method is applicable for CFTs made with high strength steel tubes as both techniques substantially underestimate the capacity of such columns. For CFTs with high strength steel tubes, it is more appropriate to assume that the steel tube fully yields when the capacity is developed. A revised version of the ACI standard method was developed by incorporating this assumption. The revised ACI method provides a fairly close estimate of the experimentally obtained capacities and those from detailed analysis.

This book is dedicated to Walter P. Moore, Jr., a leader in composite building design and engineering education. Topics include beam connection detail, advanced composites for waterfront infrastructure, evaluation of high-strength square CFT columns, push-out behavior of rectangular concrete-filled steel tubes, damping factors of composite RCS frames, structural safety of reinforced concrete flexural and compression members, behavior of new steel-concrete hybrid frame system, and hybrid RC frame-steel wall systems. 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. SP196