Accurate assessment of demand and capacity of structures is critical in developing performance-based design methodologies. In this research, new methods are presented towards quantifying demand and capacity of RCFT frames and members. An experimental database was compiled documenting local damage levels of RCFT members. The quantified information collected from the experiments was utilized in c...

A major objective of Army technology is the development of lighter and stronger platforms such as armored vehicles for Future Combat systems and Future Force. Here we show that carbon nanotubes could be the basis of such a possibility. It is shown for the first time that a carbon nanotube-iron composite, iron being the principle component of steel, has significantly enhanced mechanical strength...

Carbon nanotubes (CNTs) were deposited on various substrates namely untreated silicon and quartz, Fe-deposited silicon and quartz, HF-treated silicon, silicon nitride-deposited silicon, copper foil, and stainless steel mesh using thermal chemical vapor deposition technique. The optimum parameters for the growth and the microstructure of the synthesized CNTs on these substrates are described. Th...

We analyze the initiation and propagation of adiabatic shear bands in a thick-walled 4340 steel tube with a V-notch in the middle. The material is modeled as strain hardening, strain-rate hardening and thermal softening. The deformations are assumed to be locally adiabatic and the effect of inertia forces is considered. Two different loadings, i.e., torsional, and combined torsional and axial p...

In modern offshore installations, thin walled columns are used for energy absorption in accident situation. When this advanced offshore shock absorber is subjected to axial compressive load, plastic hinges are developed on the sides of column and the column crushes with repeatable patterns. It can absorb considerable impact energy due to large and continuous plastic deformation. This paper deve...

The assessment of response of composite seismic force resisting systems requires accurate nonlinear formulations for the composite members. In this work, reporting the first phase of a NEES project, a three-dimensional distributed plasticity formulation is presented for both circular and rectangular composite concrete-filled steel tubes (CFTs) that includes new constitutive models for the concr...

In this paper, the initiation and propagation of structural damage in a building due to the truck collision to one of its corner columns were investigated. For this purpose, a three-dimensional 4-story moment resisting steel frame with intermediate ductility was considered. The structure was designed using ETABS software under standard dead, live, and earthquake loads, and then impact loading w...

The behaviors of bar-reinforced concrete filled steel tubular columns subjected to axial load were studied. One plain concrete filled steel tubular column and three bar-reinforced concrete filled steel tubular columns were tested. The deformation of specimens and the strain of steel tubes were measured. Based on experimental researches, a simple numerical analysis method was presented to simula...

It has been a growing trend to use cold-formed steel (CFS) sections as primary structural members in low multi-story buildings due their high strength-to-weight ratios, ease of construction and flexibility manufacturing variety cross-sectional shapes. However, CFS frames are not widely used seismic regions; one important reason is that the less redundant joints generally have ductility energy d...