Gary Scott Prinz

Demands on Reduced Beam Section Connections with Out-of-Plane Skew

AbstractSome architectural designs for steel buildings require skew at moment frame connections. Reduced beam section (RBS) moment connections with out-of-plane skew have not been tested experimentally, and it is unclear how much skew, if any, should be permitted. In this study, finite-element models were used to investigate the effect of out-of-plane skew on RBS moment connection rotation capacity. The parameters investigated were the column depth, amount of skew, and model configurations (boundary conditions). The models simulated inelastic buckling in the RBS and corresponding strength degradation under cyclic loading. A low-cycle fatigue damage model was used to evaluate the results to determine if out-of-plane skew made the RBS or weld regions more susceptible to fracture. It was found that out-of-plane skew resulted in increased column twisting and minor yielding at the column flange tips, but not lower connection rotation capacity or increased susceptibility to fracture.

Effect of Slab Stiffness on EBF Link Rotation Demands and Implications for Link Ultra Low-Cycle Fatigue Susceptibility

This study aims to quantify slab contributions in EBFs by investigating the dynamic performance of two 3-story EBF configurations with and without concrete slabs: one configuration having long (flexural yielding) links and the other having shorter (shear yielding) links. Particular effort is spent investigating the relative accumulation of ultra low-cycle fatigue damage within the link regions during dynamic loading. All slab and frame geometries are modeled using shell elements. Linear springs and nodal constraints model the discrete slab-to-beam interactions. Recorded earthquake ground accelerations, scaled to design-level intensities, load the EBFs. Ultra low-cycle fatigue damage is investigated using a calibrated micro-mechanics based ductile fracture model. Results indicate reduced system-level frame demands (inter-story drift, residual drift, and link rotation) due to increased system stiffness from the concrete slabs. Reductions in these demands were larger for EBFs with long (flexural yielding) links as compared to the short (shear yielding links). Even with reduced rotation demands, EBF models with slabs sustained similar fatigue damage as the bare-steel EBF models due to increased plastic strain demands, presumably from a neutral axis shift.

On Fast Transition Between Shelters and Housing After Natural Disasters in Developing Regions

This paper presents the findings from an international workshop that brought together various NGOs, rebuilding coordinators, private sector leaders, engineers, and academics to discuss methods and issues related to fast reconstruction in developing regions affected by natural disasters. Natural disasters in developing regions often destroy homes and, together with economic conditions, force people to live in temporary shelters such as tents. Experience shows that rebuilding is often a long process because of issues related to land rights, evacuation of debris, standing building safety, coordination between local authorities, government organizations and NGO’s, etc. In order to debate on the matter, the following themes were selected for the workshop: • Stimulating local economies, involving the local unskilled workforce • Meeting basic needs, fast and safe rebuilding with appropriate materials; particularly considering the use of steel as a building material. • Adaptable construction, ways between affordable transitional shelters and sustainable long-term housing. Discussions on these three themes led to consider the particular problematic of rebuilding in urban settings. Fast rebuilding technologies suitable for high density urban environments are needed, as well as strategies for implementing such technologies in environments where construction methods are tied to habit. In this context, the idea of promoting a multi-story, multifamily, locally fabricated shelter concept for fast rebuilding in urban environments is explained.