Research Outputs
Cyclic behavior of beam-to-upright bolted connections: Experimental study of Chilean steel storage racks
In this research an experimental study to assess the cyclic behavior of bolted moment connection in racks structures is performed. The effect of bolt pretension in the response is evaluated. Sixteen full-scale steel rack joint configurations were subjected to cyclic load according to the protocol established in AISC Seismic provisions. The cyclic performance was evaluated in terms of hysteretic response, failure mechanism, energy dissipation, stiffness, and rotation on the components. Two different configurations were studied. The results showed that the steel rack connections using a 70 % of bolt pretension can accommodate a 0.8 My at 0.04 rad of drift angle, while the joints without bolt pretension reached values below 0.7 My at 4 % of rotation. The failure mechanism was controlled by weld fracture at 4 % of the rotation. A high dispersion in the energy dissipation pattern was obtained and a drop in energy dissipation of up to 4 times in all specimens tested for a 4 % rotation was developed. This phenomenon is due to the welding rupture between the beam and the L-connector. A degradation of the secant stiffness reached up to 60 % for 2 % rotation. Finally, the most important effect of bolt pretension on the cyclic response of steel rack connections was achieved in the increase of flexural resistance and rotation developed.
Influence of global slenderness and sliding pallets on seismic design of steel storage racks: A sensitivity analysis
In this research, the influence of global slenderness and sliding pallets factor on the seismic design of steel storage racks are assessed. Variations in span length, the height of storage levels, live load, and percentage of live load considered in the seismic mass are studied for different levels of seismic zone and soil type. The models were designed according to the Chilean Code NCh2369. Subsequently, a global sensitivity analysis was developed to analyze the influence of each studied parameter in the seismic design response in terms of fundamental period, drift, and base shear from a response spectral analysis approach. A total of 12000 simulations were performed. Two-hundred additional models were performed to evaluate the variation of seismic mass in the structural response. Results indicate a significant influence of live loads and seismic mass on steel racks designed for soft soils and unbrace conditions. The stiffness also modifies the performance of the racks, mainly in models using braces in the down-aisle direction and cross-aisle direction. In these cases, the seismic mass factor does not have a strong influence on structural response in comparison to the global slenderness.