Simplified Pushover Analysis for Rapid Assessment of Shear-Type Frames

A simplified pushover method for rapidly assessing the seismic capacity of shear-type frames is presented. The frame global force-displacement capacity is described as a trilinear curve passing through three limit states (LS): Damage LS (DLS), Life safety LS (LLS), and Collapse LS (CLS). The global LSs are obtained consequently to the attainment of story-level, element-level, and section-level LSs. All LS capacities are described through closed-form equations. The validity of the proposed method is verified by applying it on several reinforced concrete (RC) frames with a varying number of stories. The results obtained with such an analytical procedure show a good match with those obtained from pushover based on finite element method (FEM) analysis models, in terms of both global force-displacement capacity curves and story displacements at various LSs. The proposed method has the potential to be conveniently applied in large-scale vulnerability/risk assessment studies, where the quality and quantity of the available data call for the use of simplified yet accurate models. More refined models would in fact require significantly heavier computational efforts, not justified by the quality of the results that are usually obtained. The simplicity of the proposed method in such a context is demonstrated through the development of the fragility curves of a five-story shear-type reinforced concrete frame, starting from a predefined set of mechanical and geometrical features characterizing a building typology.

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Case Study on Vulnerability Increase for a Reinforced Concrete Frame Structure

Mathematical Modelling in Civil Engineering ◽

10.1515/mmce-2015-0014 ◽

2015 ◽

Vol 11 (3) ◽

pp. 38-45

Author(s):

Ioana Olteanu ◽

Radu Marian Canarache ◽

Mihai Budescu

Keyword(s):

Reinforced Concrete ◽

Fragility Curves ◽

Response Spectrum ◽

Frame Structure ◽

Reinforced Concrete Frame ◽

Concrete Frame ◽

Capacity Curves ◽

Performance Point ◽

Reinforced Concrete Frame Structure

Abstract Seismic vulnerability for a structure represents the susceptibility to be affected by an event with a given intensity. The vulnerability of a structure can be influenced by the design methods or by different problems that may appear during the execution process. This paper shows a case study for the vulnerability increase of a reinforced concrete frame structure in 2 different situations: a) modification produced due to code changes, meaning P100-2006 respectively P100-2013; b) modifications produced the structure taking into account the errors which have occurred during the execution process; For both cases, capacity curves were plotted considering the nonlinear analysis, also called pushover. The numerical simulation was performed in SAP2000 software. These curves were compared with the response spectrum corresponding to the site conditions in order to obtain the performance point. For accurate results, fragility curves were plotted for both considered situations, according to previous research of the authors. The paper emphasizes the importance of each stage during the execution of a structure. More over the differences in the vulnerability index show the importance on the overall behavior of the structure. Solution to increase strength and safety for the structure are also given at the end of the paper

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Response Modification Factor of RC Frames Strengthened with RC Haunches

Shock and Vibration ◽

10.1155/2020/3835015 ◽

2020 ◽

Vol 2020 ◽

pp. 1-18

Author(s):

Junaid Akbar ◽

Naveed Ahmad ◽

Muhammad Rizwan ◽

Sairash Javed ◽

Bashir Alam

Keyword(s):

Reinforced Concrete ◽

Numerical Models ◽

Lateral Force ◽

Roof Displacement ◽

Response Modification Factor ◽

Capacity Curves ◽

Displacement Capacity ◽

Rc Frames ◽

Modification Factor ◽

Force Displacement

This paper presents experimental and numerical studies carried out on two-story reinforced concrete (RC) frames having weaker beam-column joints, which were retrofitted with reinforced concrete haunches to avoid joint panel damage under seismic actions. The design philosophy of the retrofit solution is to allow beam-column members to deform inelastically and dissipate seismic energy. Shake table tests were performed on three 1 : 3 reduced scale two-story RC frame models, including one model incorporating construction deficiencies common in developing countries, which was retrofitted with two retrofit schemes using RC haunches. The focus of the experimental study was to understand the seismic behaviour of both as-built and retrofitted models and obtain the seismic response properties, i.e., lateral force-displacement capacity curves and time histories of model response displacement. The derived capacity curves were used to quantify overstrength and ductility factors of both as-built and retrofitted frames. Finite element- (FE-) based software SeismoStruct was used to develop representative numerical models, which were calibrated with the experimental data in simulating the time history response of structure roof displacement and in predicting peak roof-displacement and peak base shear force. Moreover, the FE-based numerical models were subjected to a suite of spectrum natural accelerograms, linearly scaled to multiple intensity levels for performing incremental dynamic analysis. Lateral force-displacement capacity and response curves were developed, which were analyzed to calculate the structure ductility and overstrength factors. The structure R factor is the product of ductility and overstrength factors, which exhibited substantial increase due to the proposed retrofitting technique. A case study was presented for the seismic performance assessment of RC frames with/without RC haunches in various seismic zones using the static force procedure given in seismic code and using response modification factor quantified in the present research.

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Mechanical Analysis for the Assessment of the Seismic Capacity of Masonry Buildings’ Classes in the City Centre of Sulmona (Italy)

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.133-134.623 ◽

2010 ◽

Vol 133-134 ◽

pp. 623-628

Author(s):

Marco Munari ◽

Gianluca Busolo ◽

Maria Rosa Valluzzi

Keyword(s):

Mechanical Analysis ◽

City Centre ◽

Masonry Buildings ◽

Seismic Capacity ◽

Limit States ◽

Damage Level ◽

Capacity Curves ◽

Perfectly Plastic ◽

Displacement Capacity ◽

Comparison Of The Results

A mechanical based method for the evaluation of the seismic capacity of masonry buildings’ classes in terms of damage limit states is presented: the purpose of the study is to achieve, in the framework of vulnerability analyses at territorial scale, reliable values for the damage level of vulnerability classes of masonry buildings, depending on the seismic input level. This approach is, in fact, designed as a “1st level” tool based on easily traceable information provided by expeditious surveys. Once identified a limited number of typological, physical and mechanical parameters that are necessary to define each vulnerability class, a significant number of simplified models of masonry buildings belonging to each class has been created. Non-linear static analysis of these models allowed the creation of bilinear elastic perfectly plastic capacity curves: the displacement capacity described by these curves is related with the actual displacement values required by seismic intensities associated to different return periods. It is so possible to identify, for different vulnerability classes and different seismic inputs, the loss of capacity in terms of damage level of each building. An application of the method to models representative of masonry buildings in the historical centre of Sulmona, in L’Aquila province, and a comparison of the results with others obtained with other methodologies of assessment are presented.

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Analisis Kapasitas Seismik Struktur Gedung Kantor Dinas KetahananPangan Provinsi Sumatra Barat

Jurnal Teknologi ◽

10.35134/jitekin.v10i2.19 ◽

2021 ◽

Vol 10 (2) ◽

Author(s):

Thasbih Al Fajri ◽

Rafki Imani ◽

Zakpar Siregar

Keyword(s):

Reinforced Concrete ◽

Large Scale ◽

Seismic Evaluation ◽

Strength Index ◽

Seismic Capacity ◽

Total Strength ◽

Reinforced Concrete Building ◽

Richter Scale ◽

Concrete Building ◽

West Sumatra

The office building of the food security office of West Sumatra Province is a multi-storey building with reinforced concrete structures built in earthquake-prone areas that have the potential for large-scale earthquakes such as the one that occurred in 2009. Based on USGS data, from December 2004 to October 2009 There have been 10 earthquakes measuring more than 5 on the Richter scale that rocked Indonesia and resulted in damage to buildings, both minor damage to heavy damage and evencollapsing. The big earthquake that occurred on September 30, 2009 in Padang City, West Sumatra, was measuring 7.6 on the Richter scale. In this study, evaluated the seismic capacity of a reinforced concrete building 4 (four) floors built in earthquake-prone areas in the city of Padang. The seismic capacity of the building is evaluated based on the standard published by Japan, namely The Standard for Seismic Evaluation of Existin Reinforced Concrete Building, 2001. In this evaluation, it only looks at the structural elements of the column on the first floor. Seismic capacity is expressed in terms of the lateral strength index and the ductility index of the building. The results of the evaluation of seismic capacity obtained the total strength index value of the building is 0.707. The seismic capacity of this building can be shown to be adequate or strongin earthquake-prone areas compared to the seismic capacity of reinforced concrete buildings that survived the massive earthquake of 7.6 on the Richter Scale in West Sumatra in September 2009. From the evaluation results on this building which is located in an area including the prone to strong earthquakes can be stated to be able to behave ductile and able to withstand an earthquake or not experience sudden collapse

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The effect of vertical near-field ground motions on the collapse risk of high-rise reinforced concrete frame-core wall structures

Advances in Structural Engineering ◽

10.1177/13694332211056106 ◽

2021 ◽

pp. 136943322110561

Author(s):

Arsam Taslimi ◽

Mohsen Tehranizadeh

Keyword(s):

Reinforced Concrete ◽

Seismic Performance ◽

Fragility Curves ◽

Ground Motions ◽

Reinforced Concrete Frame ◽

Engineering Structures ◽

Intensity Measures ◽

Vertical Excitation ◽

High Rise ◽

Wall Structures

According to the observations of past earthquakes, the vertical ground motions have had a striking influence on the engineering structures, especially reinforced concrete ones. Nevertheless, the number of studies on their aftermath is insufficient, and despite some endeavors done by researchers, there is still a shortage of knowledge about the inclusion of vertical excitation on the seismic performance and the collapse probability of RC buildings. Hence, the variation in the collapse risk of three high-rise RC frame-core wall structures when they undergo bi-directional ground motions is discussed. In this paper, incremental dynamic analyses are carried out under two circumstances, including the horizontal (H) and the combined horizontal and vertical (H+V) earthquakes, and the seismic fragility curves are derived. The inter-story drift ratio corresponding to the onset of collapse has also been defined. The buildings collapse risk under the two circumstances is obtained from the risk integral. Results indicate that in the H+V state, structures meet the collapse criteria for lower intensity measures. Thus, the collapse risk increases as the structures are subjected to bi-directional seismic loads, and the consideration of this effect leads to a more accurate evaluation of buildings seismic performance.

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Multi-Type Finite Elements Hybrid Model for Simulating Global Behavior of Reinforced Concrete Frames in Fires

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.353-356.2357 ◽

2013 ◽

Vol 353-356 ◽

pp. 2357-2361

Author(s):

Yong Jun Liu ◽

Yang Yang Liu ◽

Ran Bi ◽

Jing Hai Zhou

Keyword(s):

Reinforced Concrete ◽

Finite Elements ◽

Hybrid Model ◽

Large Scale ◽

Research Work ◽

Concrete Structures ◽

Concrete Frames ◽

Reinforced Concrete Frame ◽

Element Analysis ◽

Reinforced Concrete Frames

In general, reinforced concrete frames have excellent fire resistance properties, but more and more concrete buildings collapsed in fires. The majority of past research work on the response of concrete building to fire has looked at the effects of fire upon individual structural members, and most commonly when subjected to heating from standard fire tests. At present, the fire behaviors of whole reinforced concrete frame are not adequately understood. There is a great need for development of models which consider the effects of fire on the whole structure under more realistic heating regimes. There is also a fundamental requirement for further large-scale testing of concrete structures, to observe the behavior of whole concrete structures in real fires and also for validation of advanced computer analysis tools. Accuracy and efficiency are two major concerns in finite element analysis of structural response of concrete frames in fires. In this paper, a multi-type finite elements hybrid model for simulating structural behavior of whole reinforced concrete frames in real fire is suggested.

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Assessment of Seismic Vulnerability of Reinforced Concrete Frame buildings

MATEC Web of Conferences ◽

10.1051/matecconf/201814902036 ◽

2018 ◽

Vol 149 ◽

pp. 02036

Author(s):

Cherifi Fatiha ◽

Farsi Mohammed ◽

Kaci Salah

Keyword(s):

Reinforced Concrete ◽

Seismic Vulnerability ◽

Reinforced Concrete Frame ◽

Nonlinear Method ◽

Seismic Risk Analysis ◽

Building Inventory ◽

Concrete Frame ◽

Capacity Curves ◽

The North ◽

Frame Buildings

The seismic activity remains strong in the north of Algeria since no less than 30 earthquakes per month are recorded. The large number of structures built before the introduction of the seismic standards represents a high seismic risk. Analysis of damage suffered during the last earthquakes highlighted the vulnerability of the existing structures. In this study the seismic behavior of the existing buildings in Tizi-Ouzou city, located in the north of Algeria, is investigated. To make this assessment, a database was created following a building inventory based on a set of technical folders and field visits. The listed buildings have been classified into different typologies. Only reinforced concrete frame buildings are considered in this paper. The approach adopted to estimate structures damage is based on four main steps: 1) construction of capacity curves using static nonlinear method “push-over”, 2) estimate of seismic hazard, 3) determination of performance points, and finally 4) deduction of damage levels.

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