civil engineering
Maryam Kiani; Houshyar Eimani Kalehsar
Abstract
This article investigated the seismic performance of low-rise steel intermediate moment resistance frame with different percentages of mass irregularity. The irregularity of structures considered according to Iranian standard code No.. 2800 and ASCE7. For this purpose, a 3-story structure that is located ...
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This article investigated the seismic performance of low-rise steel intermediate moment resistance frame with different percentages of mass irregularity. The irregularity of structures considered according to Iranian standard code No.. 2800 and ASCE7. For this purpose, a 3-story structure that is located on soil type 2 of Iranian standard 2800 (soil type C of ASCE7) with the high-risk level hazard seismic category (region of Tehran), has been studied. The investigated structure had been subjected to nonlinear o time-history analysis under 22 records far-field ground motions considering soil-structure interaction and various mass irregularities at design basis earthquake level of Iranian standard No. 2800. This structure was simulated via OpenSees finite element software that the nonlinear behavior of geometry and materials is considered. The results showed that the drift and absolute acceleration responses of structures with flexible foundations did not have the same pattern compared to structures with rigid foundations. The considered irregularity of structures can be increased the drift value about 30 percent compared to rigid base structure. Also, the maximum absolute acceleration responses can increase about 40 percent with exciting irregularity compared to rigid base structure. In addition, the mean of absolute acceleration responses can increase about 22 percent with exciting irregularity compared to rigid base structure.
civil engineering
Morvarid Hajian; Reza Attarnejad
Abstract
The soil-structure interaction is one of the most important challenges in structural design that can significantly change the seismic response of structures. . During an earthquake, the behavior of the soil under the structure plays an important role in the response of the structure and affects the dynamic ...
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The soil-structure interaction is one of the most important challenges in structural design that can significantly change the seismic response of structures. . During an earthquake, the behavior of the soil under the structure plays an important role in the response of the structure and affects the dynamic characteristics of the structure. Therefore, there is a need for more accurate modeling of the soil environment in special structures. In engineering applications, the soil is often not modeled and its important effects are neglected, due to the unlimited nature of the soil environment and its modeling is more complicated than the structure modeling. There are different methods for modeling the soil-structure interaction phenomenon. One of the most popular methods is the method of beam on the elastic foundation. This method is based on the Winkler model, which is widely used in the design codes, but does not accurately show the changes in soil stiffness along the length of the foundation. Therefore, in the present article, the reaction of the soil under the foundation is investigated, and finally, a suitable and simplified model is presented for modeling the soil-structure interaction in engineering applications.To achieve this goal, several structures were modeled in 3D in the OpenSees environment. Then, the output of the reaction of the soil environment and the foundation of the structure has been used to estimate the hardness of the soil environment and foundation and extract simplified engineering relations
Civil Engineering
Morvarid Hajian; Reza Attarnejad
Abstract
This paper presents an exact formula for considering soil stiffness under the foundation. This formula derived from a 3D modeling of eight strip footings with different foundation widths supported on a soil medium. In the case of an earthquake, the behavior of the substructure soil plays an important ...
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This paper presents an exact formula for considering soil stiffness under the foundation. This formula derived from a 3D modeling of eight strip footings with different foundation widths supported on a soil medium. In the case of an earthquake, the behavior of the substructure soil plays an important role in the response of the structure. Studies show that the dynamic response spectrum of a structure on a flexible foundation is different from the response spectrum of a structure on a rigid foundation. Hence it is important to model the soil medium correctly to reach the best seismic results. There are different methods for modeling soil-structure interaction. These models use a constant value for modeling the soil stiffness. However, the soil stiffness varies along the foundation and should be calculated by analytical studies. This paper provides a simple formula which shows a non-uniform soil stiffness under the strip foundation and can be used for practical purposes.
Seyed Saeid Tabatabaei; Seyed hamid moafi madani
Volume 1, Issue 3 , August 2019, , Pages 10-28
Abstract
Due to the complexity of loads applied to wharves and piers because of their special application as mooring and berthing structures, their design always has many challenges. These structures have a large mass, and the piles and pile caps connections must sustain large inelastic deformations during major ...
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Due to the complexity of loads applied to wharves and piers because of their special application as mooring and berthing structures, their design always has many challenges. These structures have a large mass, and the piles and pile caps connections must sustain large inelastic deformations during major earthquakes which force-based design method cannot consider properly. So this study was undertaken to evaluate the full seismic performance of a typical synchrolift wharf located at Hormozgan province with performance-based design method by a series of static pushover analyses for three different hazard levels in accordance with ASCE/COPRI 61-14 code requirements and local seismicity. Soil-structure interaction, material overstrength, and site-specific response spectra were used to determine the displacement demands. The results reveal that using conventional force-based design method leads to the unreliable deck as well as uneconomical pile foundation designs.
