Comparison of Seismic Responses for Reinforced Concrete Buildings with Mass and Stiffness Irregularities Using Pushover and Nonlinear Time History Analysis (original) (raw)
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The prediction of inelastic seismic responses and the evaluation of seismic performance of a building structure are very important subjects in performance-based seismic design. The seismic performances of reinforced-concrete buildings evaluated by nonlinear static analysis (pushover analysis and modal pushover analysis) and nonlinear time history analysis are compared in this research. A finite element model that can accurately simulate nonlinear behavior of building is formulated by considering several important effects such as p-delta, masonry in-fill walls, soil-structure interaction, and beam-column joints that can be considered rigid zones with joint failure due to poor detailing of joints. Both global response such as system ductility demand and local response such as inter-story drift are investigated in this research. A numerical example is performed on a 9-story reinforced concrete building in Bangkok. Because Bangkok is located in soft to medium soils, response of studied building under a simulated earthquake ground motion at Bangkok site is compared with that under a measured earthquake ground motion of EI-Centro. Finally, the global and local responses obtained from the modal pushover analysis are compared with those obtained from the nonlinear dynamic analysis of MDOF system. The results show that the MPA is accurate enough for practical applications in seismic performance evaluation when compared with the nonlinear dynamic analysis of MDOF system. The results also show that ductility of the studied building can be estimated to 2.40, 2.02 and 1.65 by Fajfar, Chopra and Lee methods, respectively, for simulated ground motion at Bangkok site for a 500-year return period.
Evaluating the Seismic Performance of Low-Rise Concrete Buildings Using Nonlinear Static Analysis
Civil Engineering and Architecture, 2023
Linear force-based analysis is the conventional method for seismic design in building codes, but it has limitations in accurately predicting the seismic behaviour of buildings, especially during strong earthquakes. While nonlinear time history analysis (NTHA) is theoretically more accurate, it is limited by high computational costs and the challenge of selecting appropriate ground motion records. Nonlinear static pushover analysis (NSPA) has become a popular and simpler alternative for evaluating building performance during earthquakes, but it lacks a rigorous theoretical foundation and does not account for dynamic effects. This study aims to investigate the accuracy of NSPA in predicting the seismic behaviour of low-rise concrete buildings with 3 and 5 storeys located in a high seismic hazard zone in Indonesia. The research focuses on addressing the limitations of current methods for seismic design and evaluation of low-rise concrete buildings and aims to compare the accuracy of NSPA and NTHA in predicting the global and local responses of the buildings. Commercial finite element software is used to perform pushover analysis considering both geometric and material nonlinearity. The study's findings demonstrate that pushover analysis is slightly less conservative than NTHA in predicting the seismic response of low-rise concrete buildings. The research provides insights into the use of pushover analysis as an effective and simplified method for seismic evaluation and design of low-rise concrete buildings, while also highlighting the importance of understanding the limitations and accuracy of the method. These findings can be used to improve the seismic design of low-rise concrete buildings and enhance their safety during seismic events.
Advances in Science, Technology and Engineering Systems Journal (ASTES), ISSN: 2415-6698, 2020
In many countries and regions in the world, earthquakes are one of the most common natural disasters, which affect both human life and property. To avoid negative effects of earthquake, the nonlinear response of structures under dynamic loading should be accurately modeled to investigate their actual behavior under earthquake loading to ensure safe and sound design. To yield proper results, accurate representative structural models should be developed for the elements resisting lateral loading and representative ground motions pertaining to the site should be employed. Then relating such response to that of elastic behavior should be conducted to correlate response modification factors in design codes with actual response. The main objective of the research is to investigate the effect of basements existence and considering soil pressure on retaining walls on the seismic response modification factor for reinforced concrete structures, based on ABAQUS software analysis results using pushover analysis and time history analysis. For this purpose, experimental results of individually tested RC structures are used in order to verify modeling technique to be adopted.
The Structural Design of Tall and Special Buildings, 2012
In recent decades, shear walls and tube structures have been the most appropriate structural forms for the construction of high-rise concrete buildings. Thus, recent Reinforced Concrete (RC) tall buildings have more complicated structural behaviour than before. Therefore, studying the structural systems and associated behaviour of these types of structures is very important. The main objective of this paper is to study the linear and nonlinear behaviour of one of the tallest RC buildings, a 56-storey structure, located in a high seismic zone in Iran. In this tower, shear wall systems with irregular openings are utilized under both gravity and lateral loads and may result in some especial issues in the behaviour of structural elements such as shear walls and coupling beams. The analytical methodologies and the results obtained in the evaluation of life-safety and collapse prevention of the building are also discussed. The weak zones of the structure based on the results are introduced, and a detailed discussion of some important structural aspects of the high-rise shear wall system with consideration of the concrete time dependency and constructional sequence effects is also included.
Nonlinear static pushover Analysis of a two story Reinforced Concrete Building (Case study)
Iran plateau lies in a high seismic zone and very seismic events of magnitude 6 or greater were recorded in long term period of last times. historical events involving ground cracking and fissuring with faults displacement took place in last years. The recent seismic events have led to concerns on safety and vulnerability of RC buildings, which were most designed for gravity and limited lateral loads in the past devoid of any ductile detailing of joints. This paper presents a 3D nonlinear static analysis for seismic performance evaluation and assessment in the form of capacity curve of an existing two-story reinforced concrete frame building .The building have columns with fixed supports at base, reinforced concrete frame and flat slab systems at different floor levels. The seismic displacement response of the RC frame building is obtained using the 3D pushover analysis. The 3D static pushover analysis was carried out using SEISMOSTRUCT incorporating inelastic material behavior for ...
Non-Linear Dynamic Analysis of Earthquake Resistant Reinforced Concrete Building
Ground motion due to earthquake can cause severe damage to the structures thus a threatening to the mankind. In order to take protection against the damage of structures due to strong ground motion, it is important to know its characteristics. The most important and useful dynamic characteristics of an earthquake are peak ground acceleration, frequency and duration. These characteristics play an important role in studying the behavior of buildings under the earthquake ground motion. There are different methods of seismic analysis of building. Among the different methods of seismic analysis of structure time history analysis method is one of the most important method for structural seismic analysis generally when the estimated structural response is nonlinear in nature. In this project I am doing nonlinear dynamic analysis on RC buildings with and without shear wall with different codes. As the IS 1893-2016 is latest revision so to know new provisions this code is taken into consideration. Also, to know the other countries codal provision Eurocode 8 -1998 is also taken into consideration. It is commonly recognized that nonlinear time-history analysis method is the most correct way for simulating response and behavior of structures exposed to strong levels of seismic excitation. There are two methods of analysis one is linear method and second is nonlinear method. In linear and nonlinear analysis there are sub types one is static and another is dynamic. "Nonlinear time history analysis is known for simulating a building behavior under severe earthquake more proper than other methods" .
DergiPark (Istanbul University), 2023
In our country, which is located on an active fault line, population growth and the construction brought by this population growth are increasing rapidly. This is why it is required to consider soil-structure interaction to obtain more realistic result in structural earthquake analyses. However, considering the soil-structure interaction in the calculations sometimes gives positive results and sometimes negative results. Whether the soil is rigid or not also affects this situation. In addition, soil structure interaction starts from the moment the construction starts. Stresses and deformations occurring in a newly constructed building affect the soil on which the building sits, while simultaneously the response of the soil affects the building. Especially for loose soils, also known as soft soils, the extent of this interaction becomes even more important. This study intends to reveal the effect of soilstructure interaction in seismic analyses. Within the scope of the study finite element model were created for a 10-storey reinforced concrete. Nonlinear time history analyses were applied to the model. The results of the study show that the natural vibration period and shear forces of the building increase in the model where the soil-structure interaction is taken into account, and significant differences occur in the collapse mechanisms of the structure.
CivilEng
This paper aims to guide structural engineers on how to apply the rapid nonlinear time history analysis (RNLTHA) procedure effectively to predict seismic demand, taking into account ductility and overstrength, and effects of dynamic phenomena including cyclic degradation of strength and stiffness in structures, in a direct and expedient manner. The shortcoming of the conventional force-based approach of design involving the use of a force reduction factor to account for nonlinear effects is well recognised. Nonlinear static (pushover) analysis and dynamic nonlinear time history analysis (NLTHA) are offered as alternative methods of analysis by major codes of practices to achieve better optimisation in the use of materials. NLTHA has advantages over pushover analysis in being more direct and capable of capturing cyclic response behaviour. Despite the merits of NLTHA, its adoption in the industry has been limited, mainly because of the complexity and the higher analysis cost involved....
Procedia Engineering, 2017
Seismic design codes mostly claim that their requirements lead to Life Safety (LS) Performance Level (PL) for buildings. This is while many buildings, designed based on the current codes have shown unacceptable performance, and even have collapsed in some recent earthquakes, particularly near-source events. On this basis, it seems that the code provisions still need further improvement to create sufficient confidence in the engineering community. This study has been conducted to find out how IBC 2009 And ACI 318-2014 codes are effective in providing the LS PL in reinforced concrete multi-story regular buildings with special moment frame lateral load bearing system. For this purpose, a set of multi-story buildings up to 16 stories were considered in the highest seismic hazard zone of Tehran, and were designed based on the codes. Then, a set of near-source three-component accelerograms were employed and scaled according to the code, and a series of nonlinear time history analyses were conducted for all buildings. Roof displacement and acceleration, and base shear forces were calculated, and also the formation trend of plastic hinges and their distribution in the structures were investigated for evaluating the seismic performances. Results show that for some earthquakes the buildings performance exceed LS PL, and even in some cases they reach collapse level.
Performance Based Seismic Design of Reinforced Concrete Building By Non-Linear Static Analysis
Journal of Advances and Scholarly Researches in Allied Education
Recent earthquake disasters in the world have shown that significant damage can occur even when the buildings are designed to satisfy the codal provisions, thus exposing the inability of the codes to ensure minimum safety of the structures under an earthquake. The displacement-based approach known as the performance-based seismic design (PBSD), which evaluates how building systems are likely to perform under a variety of conditions associated with potential hazard events, is becoming very popular now. In contrast to force-based approaches, PBSD provides a systematic methodology for assessing the seismic performance of a building, thus ensuring life safety and minimum economic losses. PBSD demands the use of non-linear analysis procedures to evaluate the response of structures under lateral loads. The non-linear time history analysis is the most accurate, but requires much computational effort, time and cost. Thus, the use of nonlinear static analysis procedure known as the pushover analysis has been proposed. In pushover analysis, the magnitude of the lateral loads is incrementally increased, maintaining a predefined distribution pattern along the height of the building. It gives an insight on the progressive mode of failure of the structure, thus making it more performancebased. The scope of the present study aims at evaluation of RC buildings designed according to IS 456:2000. The non-linear static pushover analysis procedure has been used in this regard. The non-linear methods can give an Idea regarding the pattern of the plastic hinge formations and thus aid in the performance based seismic design of the structure. The pushover analysis has been carried out using ETABS Softwere. The results of analysis have been compared in terms of base shear, storey drift, storey displacements and plastic hinge rotations. An existing five storeyed residential building was analysed for seismic performance using the dual requirement of life safety under design basis earthquake (DBE) and collapse prevention under maximum considered earthquake (MCE).