One of the mechanism, used in order to provide positive control of structural vibration in the wake of earthquakes is hysteretic damper which dissipates the energy exerted into a structure. The TADAS (triangular-plate added damping and stiffness) device is one of them with elasto-plastic behavior. In this paper, the effect of ductility on the response modification factors of the frames equipped with TADAS dampers has been studied. For that matter, multi-story buildings were considered. The nonlinear incremental dynamic analysis and linear dynamic analysis have been performed using OpenSees software. In this research, seismic response modification factors for moderate and special moment resisting frames (MMRFs & SMRFs) with TADAS devices (T-MMRFs & T-SMRFs) and without them has been determined separately. The results showed that the response modification factors for TADAS frames were higher than the frames without TADAS devices. It was also found that the response modification factors for T-SMRFs were higher than T-MMRFs and also the ductility of structures has greater effect on the response modification factors of the frames with and without TADAS devices.
PUSHOVER ANALYSIS OF UNREINFORCED MASONRY STRUCTURES BY FIBER FINITE ELEMENT METHOD
A 2D finite element analysis for the numerical prediction of capacity curve of unreinforced masonry (URM) walls is conducted. The studied model is based on the fiber finite element approach. The emphasis of this paper will be on the errors obtained from fiber finite element analysis of URM structures under pushover analysis. The masonry material is modeled by different constitutive stress-strain model in compression and tension. OpenSees software is employed to analysis the URM walls. Comparison of numerical predictions with experimental data, it is shown that the fiber model employed in OpenSees cannot properly predict the behavior of URM walls with balance between accuracy and low computational efforts. Additionally, the finite element analyses results show appropriate predictions of some experimental data when the real tensile strength of masonry material is changed. Hence, from the viewpoint of this result, it is concluded that obtained results from fiber finite element analyses employed in OpenSees are unreliable because the exact behavior of masonry material is different from the adopted masonry material models used in modeling process.
USING FUZZY LOGIC APPROACH TO FIND THE COMPRESSIVE STRENGTH OF CONCRETE
The paper presents the research work is carried out to predict the 28 days compressive strength of concrete with supplementary materials such as flyash, bottom ash, super plasticizers, silica fume using fuzzy logic technique It also help in optimizing constituents available and reducing cost and efforts in studying design to develop mixes by pre-defining suitable range for experimenting. The model developed using fuzzy logic consists of 7 input parameters which are contents of cement, fine aggregates, coarse aggregates, silica fume, ash, water to cement ratio, super plasticizers and one output parameter that is compressive strength at 28 days. The model developed is completely based on experimental data of research papers.