جستجوی مقالات مرتبط با کلیدواژه "seismic design" در نشریات گروه "عمران"

Buildings with masonry materials are one of the weakest buildings against earthquakes, and the importance of proper design and correct construction of these buildings is not hidden. Among The buildings with masonry materials, the buildings with Ring beams are the most common of such buildings. Engineers use internal and external regulations and standards to design ring beam masonry buildings. The two main references for the design and construction of masonry buildings with Ring beams are the Code of Practice for Seismic Resistant Design of Buildings (Standard 2800, Fourth Edition) and the Eighth Topic of the National Building Regulations (2020 Edition) under the title of design and construction of buildings with masonry materials. The Provisions for masonry buildings with Ring beams are given in the fifth chapter of the Eighth Topic of the National Building Regulations and the Seventh Chapter of the 2800 Standard. In this research, an attempt was been made to examine the Provisions of masonry buildings with Ring beams of these two references and to identify the discrepancies and differences in the provisions. The investigation of these two references has shown that there were more than 66 cases of differences in Provisions regarding masonry buildings with Ring beams between the Eighth Topic of the National Building Regulations and the Seismic Resistant Design of Buildings. Most of the differences in the criteria were related to the sections of vertical and horizontal Ring beams, structural walls, and Non-structural walls with 34 cases and 51.5% compared to the total difference. Also, the type of soil is classified in the Eighth Topic of The National Construction Regulations with 3 types of soil and the 2800 Standard of Conduct is classified with 4 types of soil.

Based on the seismic design codes to prevent soft-story failure, columns of a soft story must be designed for amplified loads due to the discontinuity of braces or shear walls in that story. Because of the masonry infill walls discontinuity, Soft story failure has been reported in the recent earthquakes. Most national seismic design codes don't consider the effect of masonry infill walls for the design of the soft story. This paper aims to investigate the soft story failure and then present a simple formula for the design of soft-story in moment resisting frame structures. In this paper, the different arrangements of masonry infill walls are considered. Structural modeling was carried out based on reliable parameters and some national or international seismic design codes. By using nonlinear static analysis, a simple methodology is proposed and the main result is a simple formula that can be used for the engineering design of concrete moment resistant frames.

The 2800 standard is used as the main reference for theseismic design of structures in Iran. Structural analysis methods consist of two groups of linear and nonlinear analyzes that each hasdifferent parts. In this regard, the nonlinear staticanalysis method(Pushover)is applicable in accordance with the existing code. In this method, the capacity curve, which indicates the changes of the basic shear relative tothe structure of the roof's displacement. In this paper, we have investigated how to determine the capacity curve of a three-storey residential building with a bending frame systemin two main directions, based onthe fourth edition of the 2800 standard.

Every year, the phenomenon of earthquake causes a lot of human, financial and environmental losses. Transmission pipelines are one of the vital arteries that are very important, however, in the event of an earthquake can cause devastating damages. Safeguarding urban and interurban facilities, including electricity, water supply, oil and gas transmission lines, against these loads requires careful studies and engineering designs. Given that traditional methods for seismic design of pipelines such as FEM modeling and experimental methods are so expensive, a new combined method for predicting the strain of pipes based on the Artificial Neural Network (ANN) is proposed. For this purpose, the parameters of the pipeline including pipe and soil type, length, discharge, path slope, depth, etc. and earthquake-induced characteristics including earthquake acceleration, earthquake occurrence time, Peak ground acceleration (PGA), etc. were included in the model. Earthquake input parameters were considered as input parameters and pipe strains and stresses were considered as output parameter. ANSYS finite element software has also been used to simulate the pipeline and produce training data. The results of finite element software were used as input and output parameters for training and validating artificial neural network. 753 models created using ANSYS and its input/output data divided into three parts to creat ANN model. 70% of the total data were used for training, 15% for validating and 15% for testing the ANN model. Results show that the proposed Method provides a very good agreement with the computational results of the ANSYS with accuracy of 96 percent.

This work studies a new design procedure to account for accidental torsion in buildings subjected to seismic ground motions. The procedure does not require a design accidental eccentricity and it is based on a simple amplification of design parameters obtained from the corresponding model without accidental torsion. The objectives of the study are to present and to evaluate the torsion design proposed procedure. Based on representative low-rise, reinforced-concrete building models subjected to a bidirectional earthquake ground motion, several scenarios of accidental torsion were simulated using the Monte Carlo method. In the first part of the study, elastic analyses of simulated models were carried out to obtain the amplification factor value (Fat). In the second part, nonlinear analyses were performed to evaluate the design proposal based on ductility demands. Main conclusions of the study are: mean values of ductility demands do not significantly change between the torsionally balanced (TB) system and the corresponding one with accidental torsion (TU with Fat = 1.0). However, these mean values decreased about 18% for beams and 16% for columns when the torsion amplification factor (Fat = 1.2) was used in the TU systems. As for peak ductility demands, the unbalance due to accidental torsion leads to increments close to 42% for beams and 54% for columns. On the other hand, the torsion amplification factor Fat = 1.2 reduces the peak values in 25%, approximately, for beams and columns of systems with accidental torsion. Main limitations of the study are: it is based on one bidirectional ground motion (with several incidence angles) and eight structural models.

Quantitative and parametric investigations of the flexural robustness of seismically designed reinforced concrete (RC) building frames under column loss were conducted in this study. A robustness index expressed as the product of the seismic coefficient and the resistance ratio was proposed for the evaluation. Under column-loss conditions, the building frame may not sustain the effective seismic weight using the flexural mechanism as the robustness index is smaller than one. Analytical formulae of the robustness index for the three-dimensional frame model were derived using the energy method and plastic analysis technique. Seven moment-resisting RC building frames with different structural parameters were designed. Nonlinear static analyses were performed to investigate the effects of the span length, number of stories, and seismic coefficient on the robustness index. The results indicated that among these parameters, the span length was the most critical factor. The robustness index decreased with an increase in the span length. For the five-story building frames, it decreased to smaller than 1.0 when the span length increased from 4 to 6 m or larger. Nevertheless, the robustness index was approximately directly proportional to the seismic coefficient and number of stories. It was doubled as the seismic coefficient or number of stories increased from 0.1 to 0.2 or five to ten, respectively. Numerical verification confirmed that the proposed analytical formulae can provide conservative robustness evaluation for seismically designed RC building frames.