Search

Optimum design of reinforced concrete buildings in terms of performance under earthquake loads is among the fundamental issues of structural engineering. The main purpose of this study is to obtain the optimum design of plan irregularity RC buildings in terms of their performance under static and dynamic loading. Torsional irregularity in RC structures is usually caused by the unsymmetrical form of the plan geometry or the stiffness distribution of the vertical elements. Structural optimization techniques solve this problem by efficiently distributing structural elements throughout the structure to eliminate torsional irregularity in each floor layout. Different discrete mathematical models of 3D multi storey buildings were used for this study which is computationally efficient in solving such type of optimization problems. It is clearly observed that the results are changed considerably with the applying sizing optimization. The Turkish Earthquake Code TEC-2007 is used to analyse buildings and as constraint. ETABS® program is used for analysis of 3D structural. The sizing optimization problem was formulated and implemented using MATLAB® by employing Genetic Algorithm method. The design variables consist of the columns and shear walls of the building in each storey layout. [ABSTRACT FROM AUTHOR]

SUMMARY Earthquakes can cause immense damage to precast structures, rendering them inhabitable. After the 1999 Marmara earthquake in Turkey, research by the Turkish Precast Union stated that 24.50% of the precast structures were damaged with some of this damage being observed in the beam-to-column connections of the structures. Since it is essential to provide those rendered homeless by the earthquake with safe habitable accommodation, repairing medium and slight levels of damage at the connection parts should be undertaken. In order to prove that a repaired connection was sufficiently strong, a precast beam-to-column post-tensioned connection was tested in three phases. In phase one, middle level damage was observed at 6% drift at these connections. In phase two, 1.2, 2.4 and 4.8% drifts were applied three times to the test specimens. As a result of the extra loads applied, little damage was observed. In the last phase, the four connections tested in the first phase were repaired using epoxy resin and then retested. The results from the tests on the repaired precast and the reference undamaged specimens showed that the repaired specimens were sufficiently strong, thus proving that repair to damaged precast beam-to-column post-tensioned connections can be undertaken. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

SUMMARY This article presents an experiment study on precast beam-to-column connections with 15.24 mm diameter pre-stressing strands. Stress levels of 40%, 50% and 60% tensile stress were applied to the pre-stressing strands. Following the experiments, precast specimens were compared with those of the reference specimen. The load capacity of the precast specimen stressed at the level of 60% tensile stress reached 98% of the load capacity of the reference specimen, and the amount of energy dissipated by the same specimen reached 48% of that dissipated by the reference specimen. The stiffness of the same precast specimen at 1.5% drift was observed to be 71% of the reference specimen at the same drift. In the experimental studies, it was seen that the maximum stress determined in this specimen, which pre-stressing strands provide connection, reached approximately 75% of the tensile strength of the pre-stressing strands. It could not be said that topping concrete in experiment specimens increased strength. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This study compares various seismic isolation methods used to reduce the damage caused by impulsive and oscillating impacts on liquid storage tanks during earthquakes. In the research seven models were created, for the reference model no seismic isolation element was used, three models used different rubber bearings of varying hardness as the seismic isolation element and three models used dampers together with rubber bearings of differing hardness. Implementing a system of seismic isolation is very important for both the economy of a country and the environment of countries that are located in zones of high seismic risk. The Nonlinear time history analyses of the models were performed in accordance with the data from the, El Centro (USA), Northridge (USA), and Izmit (Turkey) earthquakes. The way in which the models reacted to the impact of seismic resonance differed according to the elements used. The comparison of the results show that using rubber bearings and dampers can protect the tank systems from the destructive effects of earthquakes. [ABSTRACT FROM AUTHOR]