Abstract in English:Abstract The influence of crack geometry on the buckling load of axially compressed mild steel cones was presented in this paper. The following geometrical parameter was used: bottom radius-to-top radius ratio, r2/r1=2.0; top radius-to-thickness ratio, r1/t=25; axial length-to-bottom radius ratio, L/r2=2.24; nominal shell thickness, t=1mm; cone angle, β=12.6°. The local buckling phenomenon was investigated through a series of numerical computations (50 ≤ r1/t ≤ 2000). Numerical results show that crack geometry (i.e., length and orientation) influences the buckling strength of the cones differently. For instance, as the crack length increases, the loading capacity of cones drops; cones with a circumferential crack (0°) display the most severe drop. As the crack orientation increases (from 0° to 90°) the buckling strength of the cracked cones with crack length greater than 1 increases. Whereas, for cracked cones with crack length less than 1, increasing the crack orientation has little or no effect on the buckling strength. Hence, it can be said that crack orientation has a secondary effect on the buckling of cracked conical shells.
Abstract in English:Abstract Buckling mode interaction in cold-formed steel (CFS) members must be considered for the structural design, which may lead to a significant reduction of the structural strength, usually recognized as erosion of the limit load. So far, the distortional-global (DG) buckling interaction is not covered by codes, e.g. Brazilian code NBR 14762:2010. The present investigation is aimed at the DG interaction of CFS lipped channel (LC) columns, which is the most usual section. The methodology evolves a parametric analysis, over a single LC column under DG buckling interaction. First, a study of initial geometric imperfection (IGI) sensibility is performed, with the purpose of understanding the influence of the IGI on the column’s behavior. Moreover, the parametric analysis is extended to a set of yielding stress and column lengths, to understand the ultimate load under different types of DG buckling interaction natures. Conclusions on this research have been shown that the actual global buckling equation from the Direct Strength Method is already suitable to cover the DG buckling interaction for the case of lipped channel columns.
Abstract in English:Abstract In this paper, a fully coupled fluid structure interaction (FSI) method is used to investigate the hydro-elastic response of a fully submerged standing structure under seismic excitations. Two different domains (solid and fluid) are modelled by mesh based and meshless methods, respectively. Solid domain is modeled by finite element method (FEM) and fluid domain is modeled by smoothed particle hydrodynamics (SPH). Coupling between FEM and SPH is implemented via contact mechanics, and this method differs from others in the way of coupling mechanism. Invading SPH particles are solved together with finite elements by using contact mechanics, then, a fully coupled method is achieved. In the scope of this research, different seismic excitations are applied to a rectangular tank. Half of the tank is filled with water and a submerged rubber plate is attached to its mid bottom. Thus, two-dimensional motion of rubber plate and water is investigated experimentally and simulated numerically.
Abstract in English:Abstract A proposal of a semi-rigid self-centering connection for the seismic protection of wooden structures is studied. An analytical model for the characterization of the response of the connection is developed. Quasi-static tests of a wooden column with the proposed connection allowed to validate the model and calibrate its parameters, obtaining errors smaller than 6% between analytical prediction and experimental results. The self-centering capacity and the effectiveness of the connection to limit the loads transmitted to the connected elements were evidenced. Damped free vibration tests evidenced the capacity of the connection to reduce structural vibrations. It was verified that the resistance and dissipation capacity of the connection can be modified by two design parameters that can be adjusted at the assembly. The proposed connection has desirable characteristics for its use in the protection of structural wooden frames, is versatile, and its design is simple, with explicit physical parameters.