Ali Golara

The current research presents a quick method for estimating the lateral stiffness and torsional stiffness of 3D MRF (moment-resistant frame) structures, considering irregular moment frames. This study also provides a method for calculating story displacement and rotation and natural frequencies with respect to different lateral load patterns. This study proposes a method for calculating lateral and torsional stiffness for each frame in two directions, and then converting the stiffness of all frames to one frame to obtain the deformation and natural frequency for two directions. The basic idea of the proposed innovative method was developed through the force method to obtain the lateral deformation and stiffness of 2D building structures. Then, the mentioned procedure was expanded into 3D building structures. Some examples have been made to compare the latter method with linear analysis. The results showed that the suggested method can capture 3D dynamic characteristics with accuracy compared with linear analysis.

In this paper potential use of the EGF (empirical green function) approach as a prediction tool in strong ground motion seismology is presented. This analysis was carried out on Kojoor earthquake. Here thirty possible rupture models are generated on causative fault’s plane to account for source variability. These models were based on previous study of this area and without including any knowledge of the source characteristics prior to the occurrence of this earthquake. The strong ground motion prediction provides an accurate, justifiable means to characterize site and path effects, and therefore allows the uncertainties in the predicted hazard to be because of unresolved issues about the earthquake source such as the geological constraints of a particular fault and details about the physics of earthquakes. It is found that the actual ground motion recordings fell within the range of synthesized ground motions. To conclude, it is possible to make reasonable strong ground motion “pred...

Using energy dampers in structures is highly considered for the dissipation and absorption of earthquake energy. The main advantage of using energy dampers is absorbing the earthquake energy in some sections apart from the structure. Among different types of dampers, hysteresis dampers are of special place because of low cost, high reliability and the lack of mechanical parts. In this paper, a special kind of hysteresis damper is considered under the name of buckling brace, which is provided with the aim of the study and investigation of X-brace in the seismic behavior of the steel framed buildings and for pipe and equipment racks that are extensively used in the oil and gas industry. In this paper, 62 models of steel frames with X-brace and buckling type damper are processed with different bays and heights. The frames' plasticity index, behavior coefficient, distribution type and the number of plastic hinges formed were calculated. Furthermore, suitable locations of braces for improving nonlinear behavior and suitable distribution of plastic hinges were presented and it was de-termined that for some models, the behavior coefficient of structure will increase to 1.5 times.

This  study  aims  at  evaluating  and  modeling  the  cyclic behavior  of  panel  zone  in  Special  Moment Resisting  Frame  (SMRF),  according  to  their  connection  type,  such  as welded  unreinforced  flange-bolted  web (WUF-B) connections, cover plate connection, one sided haunch and double sided haunches. In this research, some test specimens of experimental works conducted by SAC joint venture (report) were used to investigate the behavior of PZ.  In  the analytical models of  this  study, all component of connection  including bolts, and weld are modeled
using  a  surface  contact  for  shear  tab  and  bolt  and  shank,  to  evaluate  the  connection  behavior  precisely.  Then analytical  response of  the model  including cyclic behavior of beams and PZ obtained  from analytical models and experimental models were used for training of Neural Network (N.N). Then new analytical data generated by Neural Network (N.N.) used for empirical modeling of PZ according to their corresponding connection types. The results of this study showed  that  the panel zone seismic behavior depends on  the  type of connections, and plastic and elastic shears strain values of panel zone changes regarding type of connections and the proposed model presented in  this research predicts the panel zone seismic behavior accurately.

The Modeling of Panel Zone (PZ) seismic behavior, because of its role in overall ductility and lateral stiffness of steel moment frames, has been considered a challenge for years. There are some studies regarding the effects of different doubler plate thicknesses and geometric properties of PZ on its seismic behavior. But there is not much investigation on the effects of number of provided continuity plates in case of presence of one haunch or two haunches (3 to 4 continuity plates) in comparison with no haunch case (2 continuity plates) for exterior columns. In this research first detailed finite element models of 14 tested connection of SAC96 were created and analyzed then obtained cyclic behavior backbone curves of these models besides other SAC96 results for similar tests, were used for neural network training. Then seismic behavior (back bone curve of hysteretic behavior) of these data will be categorized according to continuity plate’s arrangements. As a result, for each case, an analytical model for estimation of PZ seismic behavior will be proposed.