Pushover Analysis Research Papers - Academia.edu (original) (raw)

Mevcut yapıların deprem performans, risk ve güçlendirme analizlerinde, yanındaki yapı ile olan ilişkisini uygun modelleme teknikleri ile analiz aşamasının içine dâhil ederek, sonuçların ayrı ayrı analiz edilmiş binalara göre olan farklılıklarını incelemek önemli bir konu olarak ortaya çıkmaktadır. Bu çalışmada literatürdeki, komşu binaların birbirleri ile olan etkileşim modelleri, statik itme analizi ve doğrusal olmayan hesap yöntemleri, deprem ivme kayıtlarının bir veri tabanından alınması ve tasarım spektrumuna göre ölçeklenmesi, zaman tanım alanına göre hesap yöntemi, hareket denkleminin Newmark- yöntemi ile sayısal çözümü ve kırılganlık eğrileri ile bina performans seviyelerinin belirlenmesi konuları incelenmiştir. Bitişik (komşu) ve birbirine benzer binaların, deprem performanslarının birbirileri ile olan etkileşimli ve deprem yönüne göre değişen bir şekilde yapı blokları olarak ele alınıp, hasar görebilirlik-kırılganlık eğrileri yönünden değerlendirilmeleri incelenmiş ve binaların ayrı ayrı analiz edildikleri duruma göre daha farklı sonuçlar verdiği tespit edilmiştir.

In the present paper, a performance analysis of an 18 levels IMS system building, built in Santiago de Cuba city, which is classified as very high seismic hazard level for the new Cuban code, is carried out using the static nonlinear analysis method, known as the pushover analysis in the specialized literature. A retrospective of this method and their basic objectives are also given, and his use in Cuba as well. To perform the analysis, a characterization of their components, material used in the time of construction of the building, loads analysis, including the prestressed load was done. To obtain the structure´s response and his corresponding performance level, various artificial earthquakes compatibles with the seismicity of the region, according with the seismic demand levels specified by the Cuban code, were determined and included in the analysis, even the El Centro earthquake, which is recognized as a transcendental earthquake by specialists worldwide.
The potential formations of plastic hinges were defined according to the building´s characteristics, which their occurrence was corroborate according with the structure´s results. Geometric model was obtain using SAP2000 v16 software, and using the program´s capabilities, different eatures of the structure were determined, including, dynamic response, capacity curve, hinge formation mechanism, story drifts, and
maximum building´s drift, according to different levels of demand. Remarkable results of the performance objectives in the analyzed structure were obtained for each earthquake, as follows: for the earthquakes compatible with the seismicity of the zone, the classification was Fully Operational for the Occasional event, and for the events Rare,
and Very Rare the classification was Operational, fulfilling the objectives established according to the importance of the building.

Now a day's constructions with irregularity in structure are a common feature. The irregularities such as plan, vertical and floating columns at various level and locations are introduced to achieve the architectural and functional requirements, but these features are undesirable in high seismic regional. Study of floating columns in multistory building subjected to seismic load using pushover analysis. Floating columns are provided in different positions of building such as at interior of building, corner of building and outer edges of building are analysis by non linear static method of analysis. In this first type of model is internal floating column here floating columns are provided in interior of building in every story, second type of model is providing floating column in corner of the building in each story level and third type of model is floating columns are provided in outer edge of the column in each story level. In these all models we can provide floating column in any one story level in building. The analysis is carried out by non linear static method of analysis (pushover analysis) in software ETABS2015 and comparisons are made between No floating column building and different locations of floating column building.

- by IJRASET Publication
- •
- Pushover Analysis

Failure of reinforced concrete structures during the past earthquakes has taught us the importance of evaluation of the seismic capacity of the existing buildings. Presence of irregularities is considered as a major deficiency in the seismic behavior of structures. One such forms of irregularity is the presence of re-entrant corners which causes stress concentration due to sudden changes in stiffness and torsion in the buildings due to plan asymmetry. Strengthening the notch of the re-entrant cornered buildings is very essential to ensure a good seismic performance of such buildings. Introduction of bracings and stiff shear walls are the popular methods of strengthening the buildings against their poor seismic performance. This paper aims at comparing the efficiency of these two methods of strengthening of irregular buildings. For this purpose, eight storey buildings are modeled and analyzed by response spectrum and pushover analysis methods using ETABS software. Analysis is carried out for different configurations of bracings and shear walls as strengthening elements with varying stiffness. Results of the analysis confirm the reduction in roof top displacement with the increase in the stiffness of the strengthening elements. Further, for a similar performance level the efficiency and economy of both strengthening methods are compared using a cost comparison analysis. Results of the analysis have showed that shear walls prove to be more economical compared to bracings for a given performance level.

Numerous strategies are applied to increase the stability of structure against various forces. Since the advent of the industrial revolution, materials like steel have found increasing use in the construction industry. Among the many uses of steel in construction, one major application is the use of steel as bracing members in frames. Braced frames have higher stiffness and have thus show lesser deflection when subjected to seismic or other lateral loadings. Various bracing configurations can be applied to increase the stiffness of a structure. Some of these are-diagonal, X, V, inverted V, and knee among others. This paper aims to inspect the performance of unbraced and braced frames-diagonal, X, V and inverted V. The parameters for the comparison are: maximum base shear capacity, efficiency of bracing and damping factor. It was observed that the inverted V braced frame had that most base shear capacity and showed the least amount of drift at that lateral load. Additionally, the inverted V bracing also proved to be highly economical by meeting safe drift parameter while utilizing minimum bracing material. Moreover, from the spectral acceleration curves, it was noted that inverted V braced frames showed the least excitations and that the oscillations due to the excitation decayed the fastest in the V braced frame.

- by IJRASET Publication
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- Pushover Analysis, Seismic Analysis, Staad Pro, Moment Resisting Frames

Albanian building stock is composed of reinforced concrete and masonry buildings. Most of these buildings are designed with Old Albanian Codes (KTP Codes) and some of them are constructed without any project. Considering these facts and the observations done in Albanian construction industry, presence of structural irregularities is very common in these buildings. Irregularities are weak points in the building which may cause fail of one element or total collapse of the building during an earthquake. Irregularities encountered in Albanian construction practice consist of short column, large and heavy overhangs, reinforcement details and soft story irregularity. Since Albania is a high seismic country which has been hit many times from earthquakes of different magnitudes establishes the need to study the effect of irregularities. Among all these irregularities in this study is taken in consideration the soft story effect under seismic loads in low and mid-rise buildings of Albanian construction practice. In order to get the effect of soft story irregularity in RC buildings several number of Nonlinear Static (Pushover) Analyses are done for regular frames, frames with soft story because of higher height and lack of masonry infill walls in ground story or because of the presence of both cases for the two types of structures, 3 and 6-story frames representing low and mid-rise buildings respectively. The analysis has been performed by ETABS software. The results of the analyses indicate that low and mid-rise structures with soft story irregularity due to absence of infill walls and higher height of ground story are more vulnerable during earthquakes.

- by Huseyin Bilgin
- •
- Reinforced Concrete Structures, Pushover Analysis, Soft storey

In this paper, the seismic behavior of three intermediate moment-resisting concrete space frames with unsymmetrical plan in five, seven and ten stories are evaluated by using pushover analysis. In each of these frames, both projections of the structure beyond a reentrant corner are greater than 33 percent of the plan dimension of the structure in the given direction. The performance of these buildings has been investigated using the pushover analysis. Results have been compared with those obtained from non-linear dynamic analysis.

- by Tariq Mahdi
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- Structural Engineering, Structural Dynamics, Nonlinear dynamics, Pushover Analysis

In recent years, an extensive examination going on performance of structure during a seismic event. During seismic action, building will deform in in-elastic zone, soits required evaluation which consider post-elastic behavior of structure. Performance based seismic design is a modern technique to earthquake resistance which can predict performance of structure using rigorous non-linear static analysis. Easy and most used method to evaluate performance of structure is non-linear static analysis widely known as pushover analysis. As name implies, it's a process of pushing structure horizontally, with a prescribed loading pattern incrementally, i.e "pushing" structure & plotting total applied shear force & associated lateral displacement at each increment, until structure reaches a limit state or collapse condition. It provides better understanding of seismic performance of building & also give identification of progression of damage and subsequently failure of building's structural element .By pushover analysis, One can get behavior of building in non-linear zone, which is not covered in conventional elastic design.

The issue of gravity induced instability during response to severe seismic excitation is examined. It is contended that while static instability is fully determined by the existence of at least one negative eigenvalue in the second-order tangent stiffness, this condition is necessary, but not sufficient for instability during dynamic response. It is noted that the likelihood of collapse is strongly dependent on the shape of the mechanism that controls during the critical displacement cycle and that this shape can be reasonably identified using a pushover analysis with an appropriately selected lateral load distribution. A characterization of the instability limit state based on reduction of a multistorey building to an equivalent SDOF system is presented.

Introduction One of the emerging fields in seismic design of structures is the Performance Based Design. The subject is still in the realm of research and academics, and is only slowly emerging out into the practitioner’s arena. Seismic design is slowly transforming from a stage where a linear elastic analysis for a structure was sufficient for both its elastic and ductile design, to a stage where a specially dedicated non-linear procedure is to be done, which finally influences the seismic design as a whole. The basis for the linear approach lies in the concept of the Response Reduction factor R. When a structure is designed for a Response Reduction factor of, say, R = 5, it means that only 1/5 of the seismic force is taken by the Limit State capacity of the structure. Further deflection is in its ductile behaviour and is taken by the ductile capacity of the structure. In Reinforced Concrete (RC) structures, the members (ie., beams and columns) are detailed such as to make sure tha...

- by Rahul Leslie
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- Pushover Analysis

The occurrences of (M w ¼ 7:4) Kocaeli and (M w ¼ 7:1) Duzce earthquakes in Turkey in 1999 once again demonstrate the nondamaged and high performance conditions of RC shear wall dominant structures commonly built by using the tunnel form technique. This study presents their seismic performance evaluation based on the nonlinear pushover analyses of two case studies. The contribution of transverse walls and slab-wall interaction during the 3D action, the effects of 3D and 2D modeling on the capacity-demand relation, as well as diaphragm flexibility, torsion and damping effects were investigated. An effort was spent to develop a shell element having closing-opening and rotating crack capabilities. This study shows that the applied methodology has a considerable significance for predicting the actual capacity, failure mechanism, and evaluation of the seismic response of tunnel form buildings. : S 0 0 4 5 -7 9 4 9 ( 0 2 ) 0 0 4 3 4 -0 Computers and Structures 81 www.elsevier.com/locate/compstruc

- by Erol Kalkan and +1
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- Engineering, Finite Element, Performance Evaluation, Nonlinear Analysis

There has been a growth in extensive research aimed at examining the effects of seismic events on the performance of a structure. Buildings have a tendency to exhibit inelastic deformation in during seismic activities and post-elastic behavior. Hence, better insights of the performance of structure can be obtained by examining its post-elastic behavior. Non-linear static analysis (also known as Pushover Analysis) is an improved and effective modern way of examining structural performance in the event of potential seismic impact. Such an approach involves horizontally pushing a structure using a predetermined loading pattern which constantly increases over time thereby making it possible to determine the collapse conditions, associated lateral displacement and total applied shear force. It offers a sound Perception of Structural Performance against earthquake as well as damages suffered. Thus, pushover analysis makes it feasible to ascertain the responsive behavior of buildings in non-linear zones which is not catered for by conventional elastic designs.

— Most of the steel structures in India are made of conventional steel sections (such as angle, channel and beam sections). However, new hollow steel sections (such as square and rectangular hollow sections) are gaining popularity in recent steel constructions due to a number of advantages such as its higher strength to weight ratio, better fire resistance properties, higher radius of gyration, lesser surface area, etc. This type of hollow sections can save cost up to 30 to 50% over the conventional steel sections (Tata Steel brochure, 2012). But unlike the conventional steel sections these hollow sections do not have standard connection details available in design code or in published literature. To overcome this problem the objective of the present study was identified to develop a suitable and economic connection detail between two square hollow sections which should be capable of transmitting forces smoothly and easy to be fabricated. To achieve the above objective, a square hollow beam to square hollow column connection was selected and modeled in commercial finite element software ABAQUS. This model was analyzed for nonlinear static (pushover) analysis considering a number of connection details. Following four alternative scheme of connection details were selected for this study: (i) using end-plate, (ii) using angle section, (iii) using channel sections, and (iv) using collar plates. The base model (rectangular hollow beam welded to one face of the rectangular hollow column) is also studied for reference. The performance of the selected connection details are compared and the best performing connection details is recommended for rectangular hollow beam-to-rectangular hollow column joints. The result shows that the load carrying capacity of the joint and the maximum deformation capacity is highly sensitive to the type of connection used. Also, the location of formation of plastic hinges in the structure (which can be at joint or at beam) depends highly on the type of connection used.

A 2D finite element analysis for the numerical prediction of capacity curve of unreinforced masonry (URM) walls is conducted. The studied model is based on the fiber finite element approach. The emphasis of this paper will be on the errors obtained from fiber finite element analysis of URM structures under pushover analysis. The masonry material is modeled by different constitutive stress-strain model in compression and tension. OpenSees software is employed to analysis the URM walls. Comparison of numerical predictions with experimental data, it is shown that the fiber model employed in OpenSees cannot properly predict the behavior of URM walls with balance between accuracy and low computational efforts. Additionally, the finite element analyses results show appropriate predictions of some experimental data when the real tensile strength of masonry material is changed. Hence, from the viewpoint of this result, it is concluded that obtained results from fiber finite element analyses employed in OpenSees are unreliable because the exact behavior of masonry material is different from the adopted masonry material models used in modeling process.

- by Muhammad Abbassi
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- Pushover Analysis, Masonry structures, Finite Element Simulations

The subject of this master thesis is analyzis of the behavior of reinforced concrete frame structures due to the effect of seismic loading. Three models of six-storey reinforced concrete frame structure with different ratios beam to column cross section stiffness are studied.
A pushover nonlinear static method is applied in seismic analysis. The method was implemented using SAP2000. The results obtained in accordance with FEMA 356, FEMA 440, ATC-40 and EC8 regulations are compared and analyzed.
Starting from the concept of capacity design method, a conclusion was drawn about the possibility of predicting the occurrence of nonlinear deformations of a structure depending on the stiffness ratio column to beam.

- by Dusan Spasojevic
- •
- Nonlinear Analysis, Pushover Analysis, Capacity Design, Plastic Hinges

An earthquake resisting building is one that has been deliberately designed in such a way that the structure remains safe and suffers no appreciable damage during destructive earthquake. However, it has been seen that during past earthquakes many of the buildings were collapsed due to failure of vertical members. Therefore, it is necessary to provide vertical members strong so as to sustain the design earthquake without catastrophic failure. Capacity designing is aiming towards providing vertical members stronger compared to horizontal structural elements. A structure designed with capacity design concept does not develop any suitable failure mechanism or modes of inelastic deformation which cause the failure of the structures. In capacity design of earthquake resisting structures, elements of primary lateral load resisting system are chosen suitably and designed and detailed for energy dissipation under severe inelastic deformation.

- by Pd Mt
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- Structural Engineering, Pushover Analysis
- by Rabin Dora
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- Civil Engineering, Structural Engineering, Cable Structures, Pushover Analysis

Steel is by far most useful material in construction and played an important role in last few decades. It must necessary to analyze and design a structure to perform well under seismic loads and also endow with well strength, stability and ductility for seismic design. The seismic performance of a multi-story steel frame structure is analyzed according to the provision of current Indian code (IS800-20007), seismic data and seismic factor from Indian code (IS1893-2002). Few guidelines like Applied Technology Council (ATC40) and Federal Emergency Management Agency (FEMA356) have used. Steel bracing is very useful for increasing the shear capacity of the structure. Bracing can be used as retrofit as well. There are few possibilities to arrange steel bracings such as X, V, Diagonal, K (Concentric bracings) and some eccentric bracings as well. Enough work has done in these types of bracings in several analyses. In this study typical G+8 story Steel frame buildings have analyzed, for various types of eccentric and concentric bracings. In this thesis Diamond bracing (Double K), Invert V, two types of eccentric bracings and a bare frame. Performance of each frame is studied through pushover analysis. In the present study five different types of model analyzed using pushover analysis. The pushover analysis has been carried out using SAP2000 v18, a product of computer and structure international. The results of all models are analyze and compare in term of base shear, story displacement, pushover curve, spectrum curve, performance point of the structure and story drift. If the overall performance of the buildings have found between LS-CP (Life safety – Collapse Prevent) structures is safe. The hinge results and location has been determined and it is noted that the most of the hinges begin to form in B-IO range at performance point. Keywords: Pushover analysis, performance objectives high rise steel frame with different types of bracing, bracing pattern, performance point, displacement ________________________________________________________________________________________________________

Moment resisting frames are commonly used as the dominant mode of lateral resisting system in seismic regions for a long time. Beams, columns, and beam-column joints in moment frames are proportioned and detailed to resist flexural, axial, and shearing actions that result as a building sways through multiple displacement cycles during strong earthquake ground shaking. Reinforced concrete special moment frames are used as part of seismic force-resisting systems in buildings that are designed to resist earthquakes. The poor performance of Ordinary Moment Resisting Frame (OMRF) in past earthquakes suggested special design and detailing to warrant a ductile behaviour in seismic zones of high earthquake (zone III, IV & V). Thus when a large earthquake occurs, Special Moment Resisting Frame (SMRF) which is specially detailed and is expected to have superior ductility. Special proportioning and detailing requirements result in a frame capable of resisting strong earthquake shaking without significant loss of stiffness or strength. These moment-resisting frames are called Ã¢â‚¬Å“Special Moment Resisting FramesÃ¢â‚¬Â because of these additional requirements, which improve the seismic resistance in comparison with less stringently detailed Intermediate and Ordinary Moment Resisting Frames.

During past earthquakes column plastic hinges are more prominent than beam hinges which gives rise to global structural damage and high life threatening risk. All the structural components transfers their forces through column and column than shares it with foundation to soil, so u can imagine if column fails whole structure can collapse this is strong beam weak column concept. By making column more moment resistant than beams the plastic hinges shifts to beam and avoids the global damage in this case only beam will show flexure as a sign of beam damage and the people will have adequate time to evacuate the place and beam failure will only limit to a particular storey. This concept is strong column weak beam. In this paper three RC frame of 5, 8 and 12 storey height are investigated for strong column weak beam concept for zone 5 and medium soil and moment capacities are checked as per IS1893:2016. For checking the performance of plastic hinges of column and beam non linear static analysis (pushover analysis) is done in ETABS 2016 these hinges are checked and verified according to acceptance criteria given in FEMA 356. Base shear and performance point with displacement is checked for all frames.

- by IAEME Publication
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- Etabs, Pushover Analysis, Performance Point

This paper presents the results of analyzing 17 models with nonlinear static analysis. The models are 5, 10 and 15-story frame-wall structures with Re-entrant corners. The participations of frames to resist the shear force range between 25% and 60%. Moreover, There are 3 frame models used for comparing the performance of dual systems and frame systems. The lateral load pattern is first-mode pattern. The performance points are calculated by Equivalent Linearization and the target displacements are calculated by Displacement Modification. The results are compared with the roof displacements calculated by nonlinear dynamic analysis. The plastic hinges have been studied and numbers of plastic hinges have been compared with the change of frames participations.

- by Ihssan Tarsha
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- Civil Engineering, Structural Engineering, Pushover Analysis

Struktur gedung tidak beraturan memiliki resiko timbulnya torsi pada saat terjadi pergoyangan struktur akibat gerakan tanah saat gempa, menyebabkan pusat massa dan pusat kekakuan struktur tidak terletak pada titik yang sama atau berhimpit sehingga mempengaruhi kinerja struktur.
Pemodelan struktur yang ditinjau dalam tugas akhir ini adalah struktur beraturan (simetris) dan struktur ketidakberaturan horizontal yang memiliki karakteristik ketidakberaturan torsi tipe 1.a. kemudian dianalisis baik beban gravitasi dan beban gempa mengacu pada SNI 03-1726-2012 menggunakan program ETABS v.9.6.0. Dilanjutkan dengan melakukan pushover analysis dari struktur gedung beraturan dan struktur gedung tidakberaturan. Mengacu pada FEMA 451 b bahwa dengan dilakukan perencanaan urutan sendi plastis mampu meningkatkan redundansi lokal struktur. Dalam tugas akhir ini upaya untuk meningkatkan kinerja struktur melalui perencanaaan urutan sendi plastis dilakukan dengan menambahkan tulangan pada elemen balok dan kolom pada lokasi tertentu yang membutuhkan perhatian khusus dan dianalisa dengan metode pushover untuk mengetahui komparasi yang relevan pada struktur beraturan dan struktur ketidakberaturan torsi tipe 1.a. terhadap kondisi sendi plastis terjadi secara serentak. Sehingga struktur memiliki kinerja yang maksimal dan juga perencanaan lebih ekonomis dengan dilakukannya perencanaan urutan sendi plastis.
Dengan dilakukannya perencanaan urutan sendi plastis pada struktur beraturan dan struktur ketidakberaturan torsi bahwa struktur ketidakberaturan torsi memiliki kinerja yang efektif dibandingkan dengan struktur beraturan. Struktur beraturan dengan perencanaan sendi plastis pola 4 pushover arah X prosentase peningkatan tulangan mencapai 75% pada elemen balok dan kolom kinerja titik kinerja struktur (performance point) berdasarkan nilai displacement sebesar 57% dan base shear 53%. Dilanjutkan dengan pola 5 perencanaan urutan sendi plastis arah X prosentase peningkatan tulangan mencapai 47% diperoleh nilai displacement sebesar 25% dan base shear 38%. Perencanaan sendi plastis pada struktur ketidakberaturan torsi tipe 1.a. dengan pola 4 pushover arah X prosentase peningkatan tulangan mencapai 75% pada elemen balok dan kolom kinerja titik kinerja struktur (performance point) berdasarkan nilai displacement sebesar 65% dan base shear 51%. Dilanjutkan dengan pola 5 perencanaan urutan sendi plastis dengan X prosentase peningkatan tulangan mencapai 45% diperoleh nilai displacement sebesar 50% dan base shear 40%. Hanya saja penambahan tulangan pada pola 4 perencanaan urutan sendi plastis ini dinilai boros. Maka dengan pola 5 perencanaan urutan sendi plastis dinilai memiliki kinerja yang lebih baik dan ekonomis. Indeks redundansi dari kedua struktur yang ditinjau mengalami peningkatan yang signifikan dengan perencanaan sendi plastis pada kolom dibandingkan dengan perencanaan urutan sendi plastis pada elemen balok saja.

The research revealed that three major factors, such as reserved strength, ductility and structural redundance Behaviour of multi-storey framed buildings throughout strong earthquake motion depend on the stiffness, strength and mass distribution in horizontal as well as vertical planes of the buildings. Damage occurring due to earthquake ground motion mainly starts at locations where structural weakness is present in the frames of multi-storey buildings. This weakness further increases and concentrates on the damage of structures by plastification resulting in the complete collapse of the building. In many cases, weakness occurs due to discontinuities in stiffness, mass or strength between two successive storeys. The storey discontinuities are often due to immediate variations in the geometry of frames along with the height. In past earthquakes, there are many examples of building failure due to such type of discontinuity in a vertical direction. Irregularity in configuration either in elevation or plan was sometimes recognized as one of the main causes of building failure during earthquakes. A common type of vertical irregularity (geometrical) in building develops due to a sudden reduction in the lateral dimension at specific levels of the building. This type of building is known as setback building. Many investigations have been performed to understand the behavior of setback buildings and to visualize methods for further improvement in performance.

- by IJRASET Publication
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- Pushover Analysis

Generally, in open ground storey buildings, unreinforced brick masonry infills are present in all floors except the ground storey. This leads to severe stiffness and strength irregularity and even sometimes leads to torsion irregularity. Buildings with these irregularities have consistently shown poor performance during past earthquakes. Normally, infills are considered as non-structural member; however, practically it provides significant stiffness under lateral load. If special provisions have not been followed in design, absence of infill at ground storey will lead to formation of soft ground storey. Under lateral loading, lack of infill stiffness will lead to larger inter-storey drift concentrated to ground storey leading to an early formation of plastic hinges, further impending collapse of structure. For this purpose, performance based analysis of soft storey structure was carried out. An existing open ground storey building with G+5 storey have been considered in zone V. Infill walls are modelled using procedure given in FEMA. Linear dynamic response spectrum analysis &Non-linear static pushover analysis has been done & studied effects of infills on dynamic characteristics, yield patterns, seismic performance using SAP 2000. Time period and base shear was obtained & compared by linear analysis. The pushover curves between base shear & displacement are plotted and compared.

The past earthquakes in which many reinforced concrete structures were severely damaged have indicated the need for evaluating the seismic adequacy of buildings. In particular, the seismic rehabilitation of older concrete structures in high seismicity areas is a matter of growing concern and an acceptable level of safety must be established. To make such an assessment, simplified linear-elastic methods are not adequate. Thus here we carried out the project using non-linear elastic method called as Pushover analysis which helps to assess the damage vulnerability of buildings. Earthquakes are most devastating natural hazards in terms of life and property of any region. The behavior of the structure greatly depends on size, shape and geometry of that structure i.e, vertical and horizontal irregularities and path of load transferring to the supporting ground. Irregularity in building attracts forces which lead to stress concentration at the point of irregularity; subsequently it leads to localized failure of that structure. The present study focuses on seismic performance of irregular RC models having irregularities i.e. plan re-entrant corner irregularity. For this purpose ETABS a finite element software has been used. Here 3-D RC models are modeled and analyzed for seismic zones IV and V. Roof displacement; Base shear carried; performance points; number of hinges formed are the parameters used to quantify the performance of the structure.

- by IJSRD Journal
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- Pushover Analysis, Irregularity, Performance Point

This study investigates the performance of the setback building with open ground storey using nonlinear static pushover analysis. Such type of building possess vertical geometric and mass irregularity as well as stiffness irregularity. In this paper, plan irregular setback building with open ground storey resting on plain and sloping ground which makes the building so weak to survive during earthquake. An attempt has made to alleviate effects of these irregularities during earthquake by replacing OGS columns by Reinforced concrete filled steel tube columns. RCFST columns increases the stiffness of the OGS which offset the soft storey effect as well as reduce storey displacement, drift and torsional response significantly. From hinges results, it can be observed that performance of the building is improved significantly.

- by GRD JOURNALS
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- Pushover Analysis, Irregularity, Soft storey

A simplified methodology for predicting the median and dispersion of collapse capacity of momentresisting frame and shear wall structural systems subjected to seismic excitations is proposed. The method is based on nonlinear static (pushover) analysis. Simple mathematical models denoted as ''generic structures'' are utilized to model moment-resisting frames and shear walls. After examining a wide range of structural parameters of the generic structures, a comprehensive database of collapse fragilities and pushover curves (using ASCE 7-05 lateral load pattern) are generated. Based on the obtained pushover curves, closed-form equations for estimation of median and dispersion of building collapse fragility curves are developed using multivariate regression analysis. Comparing the estimates of the median collapse capacity calculated from the closed-form equations with the actual collapse capacities determined from nonlinear response-history analysis indicates that the simplified methodology is reliable. The effectiveness of this methodology for predicting the median collapse capacity of frame and wall structures is further demonstrated with two case studies of structural systems designed based on current seismic provisions.

A new pushover analysis procedure derived through adaptive modal combinations ͑AMC͒ is proposed for evaluating the seismic performance of building structures. The methodology offers a direct multimode technique to estimate seismic demands and attempts to integrate concepts built into the capacity spectrum method recommended in ATC-40 ͑1996͒, the adaptive method originally proposed by Gupta and Kunnath ͑2000͒ and the modal pushover analysis advocated by Chopra and Goel ͑2002͒. The AMC procedure accounts for higher mode effects by combining the response of individual modal pushover analyses and incorporates the effects of varying dynamic characteristics during the inelastic response via its adaptive feature. The applied lateral forces used in the progressive pushover analysis are based on instantaneous inertia force distributions across the height of the building for each mode. A novel feature of the procedure is that the target displacement is estimated and updated dynamically during the analysis by incorporating energy-based modal capacity curves in conjunction with constant-ductility capacity spectra. Hence it eliminates the need to approximate the target displacement prior to commencing the pushover analysis. The methodology is applied to two existing steel moment-frame buildings and it is demonstrated that the AMC procedure can reasonably estimate critical demand parameters such as roof displacement and interstory drift for both far-fault and near-fault records, and consequently provides a reliable tool for performance assessment of building structures.

- by Erol Kalkan
- •
- Civil Engineering, Structural Engineering, Static Analysis, Performance Assessment

This study proposes a procedure for developing seismic fragility curves for a pile-supported wharf. A typical pile-supported wharf, as commonly used in the ports of Taiwan, is chosen for demonstration. For a structural model of the wharf, the deck is modeled by shell elements and the Winkler model is used for the pile-soil system, in which the piles and soils are represented by beam elements and springs, respectively. A pushover analysis with lateral loads distributed according to the fundamental modal shape of the wharf structure is conducted to deduce the capacity curve of the wharf. The procedure for developing fragility curves can be explicitly performed using the spreadsheet platform in Microsoft EXCEL. First, quantitative criteria for damage states are established from the sequence of development of plastic zones. Then a nonlinear static procedure called the Spectrum Capacity Method (CSM) is used to efficiently construct a response matrix of the wharf to 24 earthquake events with differing levels of peak ground acceleration (PGA). Based on the damage criteria and the response matrix, the fragility curves of the wharf can be thus constructed through simple statistical analysis. Shifted lognormal cumulative distribution functions are also employed to better approximate the fragility curves for practical applications.

- by Shang-yi Hsu
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- Civil Engineering, Geophysics, Statistical Analysis, Pushover Analysis

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.

- by Mr Frank
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- Structural Engineering, Dynamic Analysis, Pushover Analysis, Seismic Evaluation

Structural frames are often filled with infilled walls serving as partitions. Although the infills usually are not considered in the structural analysis and design, their influence on the seismic behaviour of the infilled frame structures is considerable. In the present study, a parametric study of certain infilled frames, using the strut model to capture the global effects of the infills was carried out. Three concrete planar frames of five-stories and three-bays are considered which have been designed in accordance with Turkish Codes. Pushover analysis is adopted for the evaluation of the seismic response of the frames. Each frame is subjected to four different loading cases. The results of the cases are briefly presented and compared. The effect of infill walls on seismic behavior of two sample frames with different infill arrangements was investigated. The results yield that it is essential to consider the effect of masonry infills for the seismic evaluation of moment-resisting RC frames, especially for the prediction of its ultimate state, infills having no irregularity in elevation have beneficial effect on buildings and infills appear to have a significant effect on the reduction of global lateral displacements.

- by Konuralp Girgin
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- Pushover Analysis, Plastic Hinge, Seismic response, Capacity Spectrum Method

A B S T R A C T During the recent earthquakes, it has been observed that structural irregularities are one of the main reasons of the building damage. Irregularities are weak points in a building which may cause failure of one element or total collapse of the building during an earthquake. Since Albania is a country with moderate seismicity which has been hit by earthquakes of different magnitudes many times establishes the need to study the effect of irregularities is well-founded. The main structural irregularities encountered in Albanian construction practice consist of short column, large and heavy overhangs and soft story. In this study, these types of irregularities are considered in two different types of buildings, low and mid-rise reinforced concrete frame buildings represented by 3-and 6-story respectively. Pushover analyses are deployed to get the effect of structural irregularities on RC building response. A building set is chosen to represent the existing construction practice in the region; regular framed building and buildings with irregularities such as soft stories, short columns, heavy overhangs and the presence of soft story with heavy overhangs. The analyses have been conducted by using ETABS and Seismosoft software. Pushover curves of building set are determined by nonlinear static analysis in two orthogonal directions. Comparative performance evaluations are done by considering EC8 and Albanian Seismic codes (KTP-N2-89). From the obtained results, it is observed that low and mid-rise structures with soft story-two sided overhangs and short column are more vulnerable during earthquakes.

- by Huseyin Bilgin
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- Pushover Analysis, Structural Irregularities, Building Damage, Capacity Curve

Viene presentata una panoramica delle più efficienti tecniche di analisi statica non lineare, evidenziando i progressi fatti nella formulazione di procedure con profili di carico adattivi multimodali, finalizzati alla valutazione della risposta di strutture a comportamento fortemente non lineare. Vengono poi presentate le diverse procedure che consentono di analizzare il comportamento di strutture irregolari in altezza o con grandi periodi di vibrare, nella quale la risposta è fortemente influenzata dai modi superiori. In quest’ambito viene evidenziato il ruolo della procedura Modal Pushover Analysis, che risulta fra le più efficienti nel riprodurre il comportamento di strutture fortemente irregolari in pianta e in elevazione a comportamento debolmente non lineare. Viene ripresa una tecnica di combinazione dei contributi modali mediante la CQC, implementata attraverso l’impiego di coefficienti di correlazione non lineari per sistemi isteretici. Un esempio numerico nel quale la tecnica viene applicata per la prima volta a sistemi spaziali irregolari in pianta ne mostra l’efficacia in questo campo.

- by Gabriele Testa, Ph.D. Student and +1
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- Earthquake Engineering, Seismic Engineering, Pushover Analysis, NONLINEAR STATIC (OR PUSHOVER) ANALYSIS

Nonlinear static analysis is an iterative procedure so it is difficult to solve by hand calculation and that's why software is required to do nonlinear static analysis. ETABS 9.7 have features to perform nonlinear static analysis. This... more

- by 家仁劉
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- Pushover Analysis

Many reinforced concrete structures were severely damaged in past earthquakes have indicated the need for retrofit. This seismic rehabilitation of older concrete structures in high seismicity areas is a matter of growing concern. Simplified linear-elastic methods are not adequate to assess such seismic deficient buildings. Thus here we carried out the project using Pushover analysis a non-linear elastic method which helps to assess the seismic deficiency or damage vulnerability of buildings. Earthquakes cause the loss in terms of life and property of any region so they are the most devastating natural hazards. size, shape and geometry of that structure i.e, vertical and horizontal irregularities and path of load transferring to the supporting ground will affect the behaviour of the structure. Irregularity in building attracts forces which lead to stress concentration at the point of irregularity and leads to collapse or localized failure of that structure. The present study focuses on seismic performance of irregular RC models having irregularities i.e. vertical geometric irregularity. ETABS a finite element software has been used to analyse the structure. Here 3-D RC models are modeled and analyzed for seismic zones IV and V. Roof displacement; Performance point; Base shear carried; Number of Hinges formed are the parameters used to quantify the performance of the structure.

- by IJSRD Journal
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- Pushover Analysis, Performance Point, Hinge

Pushover analysis is a static, nonlinear procedure using simplified nonlinear technique to estimate seismic structural deformations. It is an incremental static analysis used to determine the force-displacement relationship, or the capacity curve, for a structure or structural element. The analysis involves applying horizontal loads, in a prescribed pattern, to the structure incrementally, i.e. pushing the structure and plotting the total applied shear force and associated lateral displacement at each increment, until the structure or collapse condition. In technique a computer model of the building is subjected to a lateral load of a certain shape (i.e., inverted triangular or uniform). The intensity of the lateral load is slowly increased and the sequence of cracks, yielding, plastic hinge formation, and failure of various structural components is recorded. Pushover analysis can provide a significant insight into the weak links in seismic performance of a structure. The performance criteria for pushover analysis are generally established as the desired state of the building given roof-top or spectral displacement amplitude.

- by Editor IJRET
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- Civil Engineering, Structural Engineering, Pushover Analysis

Owing to the simplicity of inelastic static pushover analysis compared to inelastic dynamic analysis, the study of this technique has been the subject of many investigations in recent years. In this paper, the validity and the applicability of this technique are assessed by comparison with 'dynamic pushover' idealised envelopes obtained from incremental dynamic collapse analysis. This is undertaken using natural and artificial earthquake records imposed on 12 RC buildings of different characteristics. This involves successive scaling and application of each accelerogram followed by assessment of the maximum response, up to the achievement of the structural collapse. The results of over one hundred inelastic dynamic analyses using a detailed 2D modelling approach for each of the twelve RC buildings have been utilised to develop the dynamic pushover envelopes and compare these with the static pushover results with different load patterns. Good correlation is obtained between the calculated idealised envelopes of the dynamic analyses and static pushover results for a defined class of structure. Where discrepancies were observed, extensive investigations based on Fourier amplitude analysis of the response were undertaken and conservative assumptions were recommended.

Pushover analysis has been in the academic-research arena for quite long. The papers published in this field usually deals mostly with proposed improvements to the approach, expecting the reader to know the basics of the topic... while the common structural design practitioner, not knowing the basics, is left out from participating in those discussions. Here I’m making an effort to bridge that gap by explaining the Pushover analysis, from basics, in its simplicity.

- by Rahul Leslie
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- Pushover Analysis

The static pushover analysis is becoming a popular tool for seismic performance evaluation of existing and new structures. The expectation is that the pushover analysis will provide adequate information on seismic demands imposed by the design ground motion on the structural system and its components. The recent advent of structural design for a particular level of earthquake performance, such as immediate post-earthquake occupancy, (termed as performance based earthquake engineering), has resulted in guidelines such as ATC-40, FEMA-356 and standards such as ASCE-41. Among the different types of analysis, pushover analysis comes forward because of its optimal accuracy, efficiency and ease of use. In the present study, the behaviour of G+20 storied R.C frame buildings (H shape in plan, with and without T shaped column) subjected to earthquake, located in seismic zone III is discussed briefly using ETABS software. Gravity loads and laterals loads as per IS 1893-2002 are applied on the structure and it is designed using IS 456. Displacement control pushover analysis is carried out.

- by Editor IJRET
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- Civil Engineering, Structural Engineering, Pushover Analysis, Seismic Evaluation

One of the evocative designs for tall buildings is embraced by the diagrid (diagonal grid) structural system. Diagrid (with a perimeter structural configurations characterized by a narrow grid of diagonal members involved both in gravity and in lateral load resistance) has emerged as a new design trend for tall-shaped complex structures due to aesthetics and structural performance. Since it requires less structural steel than a conventional steel frame, it provides for a more sustainable structure.
This study focuses on the robustness assessment of a tall diagrid structure. The aim is to provide insight on whether the gains in terms of sustainability, have a negative impact on the structural robustness the structure. Numerical comparisons for different failure scenarios are performed and presented.

- by Konstantinos Gkoumas and +1
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- Finite Element Analysis (Engineering), Structural Robustness, Pushover Analysis, Diagrids

It is critical to ensure the functionality of highway bridges after earthquakes to provide access to important facilities. Since the 1971 San Fernando earthquake, there has been a better understanding of the seismic performance of bridges. Nonetheless, there are no detailed guidelines addressing the performance of skewed highway bridges. Several parameters affect the response of skewed highway bridges under both service and seismic loads which makes their behavior complex. Therefore, there is a need for more research to study the effect of skew angle and other related factors on the performance of highway bridges. This paper examines the seismic performance of a three-span continuous concrete box girder bridge with skew angles from 0 to 60 degrees, analytically. Finite element (FE) and simplified beam-stick (BS) models of the bridge were developed using SAP2000. Different types of analysis were considered on both models such as: nonlinear static pushover, and linear and nonlinear time history analyses. A comparison was conducted between FE and BS, different skew angles, abutment support conditions, and time history and pushover analysis. It is shown that the BS model has the capability to capture the coupling due to skew and the significant modes for moderate skew angles. Boundary conditions and pushover load profile are determined to have a major effect on pushover analysis. Pushover analysis may be used to predict the maximum deformation and hinge formation adequately.

- by Gokhan Pekcan
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- Civil Engineering, Finite Element, Pushover Analysis, Seismic response

Most of the reinforced concrete (RC) structures are not designed to resist major or moderate earthquakes. The designs of such building are regularly done by using gravity loading without considering the earthquake load. Thus these buildings are vulnerable during the event of an earthquake.. In present study bare frame and soft storey are modeled considering special and ordinary moment resisting frame (SMRF & OMRF) for medium soil profile under zone III. The masonry infill panels were modeled as equivalent diagonal strut seven and ten storey buildings are considered to represent medium and high rise buildings , equivalent static and response spectrum analysis was performed on bare frame, infill frames as brick and infill frame as solid concrete block using SAP 2000 V15 software. Nonlinear static pushover analysis carried out for default-hinge properties, M, PM, V and P hinges are applied to beam, column and strut available in some programs based on the FEMA-356 and ATC-40 guidelines. While such documents provide the hinge properties for several ranges of detailing, programs may implement averaged values. The performance of building frames were compared with bare frame, in terms of ductility, safety, and stiffness. The investigation concludes that the performance of the buildings having non-ductile moment resisting frames can be improved by adding infill walls and SMRF building models are found more resistant to earthquake loads as compared to the OMRF building models in terms of performance level, performance point and hinging variation the performance of building for OMRF lies in LS to CP range where as SMRF are found under life safety range ,this shows in high seismicity region the ductile detailing must be adopted to avoid the vulnerability of building for tremor loads.

- by Editor IJRET
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- Civil Engineering, Structural Engineering, Pushover Analysis, Stiffness

The evaluation of seismic performance of existing buildings is essential to determine an acceptable solution in terms of capacity and performance. In this paper pushover analysis of a 3-storey steel building is carried out by incorporating inelastic material behaviour and assigning inelastic effects to plastic hinges at member ends. An analytical procedure is developed to estimate the inelastic deformations of beams, columns and connections and the same is incorporated for the analysis of the building frame with semi-rigid connections using finite element analysis software. The capacity curve obtained is compared with acceptable levels of damage for the evaluation of seismic performance of the building.

- by CINITHA AJITH
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- Civil Engineering, Earthquake Engineering, Earthquake, Structural Design

In this study, the seismic design and performance of composite steel-concrete frames are studied. The new Eurocode 4 and Eurocode 8, which are in a preliminary stage at the moment, are employed for the design of six composite steel-concrete frames. The deficiencies of the codes and the clauses that cause difficulties to the designer are discussed. The inelastic static pushover analysis is employed for obtaining the response of the frames and the overstrength factors. The evaluation of the response modification factor takes place by performing incremental time-history analysis up to the satisfaction of the yield and collapse limit states in order to investigate the conservatism of the code. The last purpose of this study is to investigate if elastically designed structures can behave in a dissipative mode.

- by André Plumier and +1
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- Civil Engineering, Seismic Design, Pushover Analysis, Concrete Structure

Many urban multi-storey buildings in India today have open first storey as an unavoidable feature. This is primarily being adopted to accommodate parking or reception lobbies in the first storey. This paper highlights the importance of explicitly recognizing the presence of the open first storey in the analysis of the building and also for immediate measures to prevent the indiscriminate use of soft first storeys in buildings. Alternate measures, involving stiffness balance of the open first storey and the storey above, are proposed to reduce the irregularity introduced by the open first storey. The structural engineering profession has been using the nonlinear static procedure (NSP) or pushover analysis. Modeling for such analysis requires the determination of the nonlinear properties of each component in the structure, quantified by strength and deformation capacities, which depend on the modeling assumptions. Pushover analysis is carried out for either user-defined nonlinear hinge properties or default-hinge properties, available in some programs based on the FEMA-356 and ATC-40 guidelines. This paper aims to evaluate the zone –II selected reinforced concrete building to conduct the non-linear static analysis (Pushover Analysis). The pushover analysis shows the pushover curves, capacity spectrum, plastic hinges and performance level of the building. This non-linear static analysis gives better understanding and more accurate seismic performance of buildings of the damage or failure element.

In Pakistan most of the non-engineered buildings, like houses or small scale commercial centers are infilled with masonry but the behavior and interaction of masonry with rest of structure is not taken into account. During the massive 2005 earthquake, in Kashmir region of Pakistan, immense damage occurred due to masonry failure and caused a lot of life loss. A two storey reinforced concrete masonry infilled frame structure was modelled in DRAIN-3DX based on Finite Element Analysis (FEA) approach. FEA of infill frames includes modeling of beams, columns, and modeling of masonry infill. Masonry infill was modelled as strut subjected to compressional force and will unload inelastically after the removal of force.

Buildings are subject to different lateral loads out of which seismic loads and wind loads are predominant. The
earthquake and seismic phenomenon of structures is one of the most devastating and dangerous havoc not only to human life
but also to the economy of the nation life as well.
Therefore it is necessary to study the vulnerability characteristics of the structures when subjected to such a phenomenon or
earthquake excitations to reduce the impact of the socioeconomic calamity. Wind loads are due to wind pressure acting on the
buildings. Some of the pressure acting on exposed surfaces of structural members is directly resisted by bending of these
members.
In this present work a brief discussion of how a structure behaves when subjected to lateral loads (includes seismic loads and
wind loads) and its behavior under acting such loads is found. And also the behavior of the structure is studied when it is
interpreted with setbacks by calculating the displacements and static pushover analysis is carried out to find its performance
point.

- by IJRASET Publication
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- Pushover Analysis