جستجوی مقالات مرتبط با کلیدواژه « ساختمان های فولادی » در نشریات گروه « برق »

In the Current seismic codes, the earthquake load on the buildings depends to period of structure. More of these codes use the empirical relations to estimate the period of structures. These relations are suggested for the rigid floor structures. Then use of these relations for semi-rigid and flexible diaphragms is not accurate and cause error in determination of seismic load of structures. This topic is more important for the stiffened structures such as: structures with shear wall or bracing together joist-floors with lower rigidity in one direction and semi-rigid behavior. In this paper, the period of the braced steel building with block-joist floors for two different cases of real modeling without rigid diaphragm assumption and ideal modeling with rigid diaphragm assumption are compared and effect of flexibility of diaphragms on the period of structure is investigated. Also, for fast estimation of period of structures with flexible diaphragms, the simple equations are proposed.

Post-tensioned steel connections are new type of connections in which bending moment and shear force at the end of the beam are transmitted to the column using high strength strands. In these connections، energy dissipaters are used for increasing energy dissipation and controlling plastic deformations. In the present paper، the complete numerical model of the experimentally tested connection has been created using ABAQUS software; and cyclic response of this model is compared with the experimental results. Then، simplified numerical model of the connection with the shorter time of modeling and analysis has been created. In this simplified simulation، to model strands، the beam elements are used instead of solid elements، and welding is used instead of bolts for connecting the energy dissipater angles to the beam. A good agreement between cyclic response of numerical model and experimental result was obtained. Also، the results of the full model and simplified model are very close to each other. Therefore، the use of simplified model is confidence and it needs less time for analysis. In addition، the size of software output data is much less. Because، the construction of laboratory samples needs more time and cost compared to computer simulations، therefore، the numerical models can be created simply for modeling the connections with post-tensioned and energy dissipation systems، and effects of these systems on the connection behavior can be studied.

Up to now many research projects have been conducted regarding vibration control of structures and reducing seismic demands of main structural members leading to better lateral performance. Passive metallic dampers as fuse elements has attracted many researchers according to their absorbing and damping capacity under severe cyclic loading condition. This lecture analytically investigates effect of adding rhombic metallic dampers on seismic performance of steel frames to be strengthened. Nonlinear time history analysis results of 5 story moment resisting frame showed (53% - 143%) increase in PGA amount that structure can resist and 40% reduction in roof displacement. Using dampers in bracing system in 7 story braced frame caused (54% - 175%) increase in PGA amount that structure can resist, increase in effective equivalent damping to 20% and 72% reduction in base shear. Using the damping strategy, seismic performance of both two type frames got improved from “collapse” level to “operational” level.