Numerical Simulation of Reinforced Concrete Shear Walls Using Force-Based Fiber Element Method

Reinforced concrete shear walls are the structural elements that considerably increase the seismic performance of buildings. Fiber elements and fiber-spring elements are used for the modeling of the inelastic behavior of these elements. The Fiber Element Method provides a certain amount of accuracy for the modeling of reinforced concrete shear walls. However, the studies related to this method are still in progress. In this study, the efficiency of the force-based Fiber Element Method is investigated for different damping ratios and different damping types that used in the structural damping for reinforced concrete shear wall structures. Two shear wall structures that subjected to seismic loads are used for the comparison of numerical analysis and experimental results. The comparisons are achieved according to the absolute maximum values of the overturning moment, the base shear force, and the roof displacement. Rayleigh damping and stiffness-proportional damping types for the damping ratios that vary between 2-3% provide better results than mass-proportional damping. Additionally, the optimum number of fiber element for Rayleigh and stiffness-proportional damping types is determined for the optimum damping ratio that provides minimum differences between numerical analysis and experimental results. For these damping types, when the length of a fiber is smaller than 3% of the longitudinal length of the shear wall at the optimum damping ratios, the roof displacement differences between numerical analysis and experimental results are less than 2.5%.

Effects of Base Isolation and Infill Panels on the Nonlinear Time History Analysis of Reinforced Concrete Building

This paper presents the predicted results of nonlinear time history analysis of 11 storey (G+10) Reinforced Concrete (RC) residential building under the effects of a strong earthquake. The paper includes studying the effects of using Lead Rubber Bearings (LRB) as base isolators to improve the performance of RC building to sustain the impact of an earthquake. It also includes the effects of the infill panels on the overall dynamic response of both fixed base and base-isolated buildings subjected to a strong earthquake. The main results that are presented in this study include the variation of roof acceleration, roof displacement, base shear with time. The effects of using LRB and including the infill panels on the storey drift are also presented. Maximum reduction in the story drift was obtained when infill panels are included in the analysis of the base isolated building. The inclusion of the infill panels has only marginal effects on the variation of roof displacement with time when the building is isolated by LRB. The main important improvements that emerged from using LRB as well as the infill panels in the analysis are the reduction of inelastic energy and upgrading the elastic one that is summed up along the period of the earthquake.

Analisis Kapasitas Lateral Pada Fondasi Tiang Tunggal Dan Tiang Kelompok Pada Tanah Pasir

Fondasi ialah bagian dari suatu sistem rekayasa yang meneruskan beban yang ditopang oleh fondasi dan beratnya sendiri kedalam tanah dan batuan yang terletak dibawahnya. Pada jurnal ini, dilakukan analisa kapasitas lateral tiang tunggal dan tiang kelompok pada tanah pasir. Untuk dapat menganalisis tiang pancang tunggal dan tiang kelompok pada tanah pasir dalam kondisi elastic dapat dilakukan dengan metode analisis statik non linier atau analisis pushover. Analisis pushover adalah prosedur analisis untuk mengetahui keruntuhan suatu bangunan dengan memberikan suatu pola beban statik tertentu dalam arah lateral yang besarnya akan ditingkatkan secara bertahap sampai struktur tersebut mencapai target displacement tertentu atau mencapai pola keruntuhan tertentu. Dari hasil analisis pushover terhadap suatu tiang dihasilkan kurva yang menghubungkan antara base shear dan roof displacement atau disebut kurva kapasitas. Dari kurva kapasitas tersebut dapat dilihat perilaku suatu tiang dari kondisi elastis sampai plastis hingga mengalami kegagalan. Dengan adanya kurva kapasitas yang diperoleh, kita dapat melihat tingkat kinerja suatu tiang berdasarkan metode spektrum kapasitas berdasarkan peraturan ATC-40 dan Pushover Analysis of Underground Structures. The foundation is part of an engineering system that forwards the burden supported by the foundation and its own weight into the soil and rocks beneath. In this journal, an analysis of the lateral capacity of single piles and group piles is carried out on sandy soil. To be able to analyze a single pile and group piles on sandy soil in elastic conditions can be done by non-linear static analysis or pushover analysis. Pushover analysis is an analysis procedure to determine the collapse of a building by providing a certain static load pattern in the lateral direction whose magnitude will be increased gradually until the structure reaches a certain displacement target or reaches a certain collapse pattern. From the results of pushover analysis on a pile, a curve that connects the base shear and roof displacement is called a capacity curve. From the capacity curve, it can be seen the behavior of a pile from elastic to plastic conditions to failure. With the obtained capacity curve, we can see the level of performance of a pile based on the capacity spectrum method based on ATC-40 regulations and Pushover Analysis of Underground Structures.

STUDI STUDI KAJIAN PERILAKU BANGUNAN GEDUNG KAYU BERTINGKAT RENDAH DENGAN ANALISIS TIME HISTORY

Hotel dirancang menyerupai rumah panggung yang merupakan rumah khas bagi masyarakat Bugis-Makassar. Material struktur yang dipilih adalah kayu Libung karena ringan, dan fleksibel. Struktur bangunan dimodelkan menjadi Model 1 (konvensional) dan Model 2 (link). Beban gempa menggunakan analisis riwayat waktu. Analisis riwayat waktu dengan empat beban gempa referensi yang diskalakan dapat digunakan untuk memberikan gambaran gaya lateral yang bekerja pada bangunan. Struktur kayu tersebut dievaluasi terhadap parameter gaya geser dasar, simpangan antarlantai, dan taraf kinerja struktur. Taraf kinerja struktur mengacu pada ATC-40 yang ditentukan dari rasio maximum total roof displacement terhadap ketinggian struktur. Model struktur dengan link memiliki nilai periode lebih besar daripada struktur model konvensional, karena memiliki kekakuan sambungan balok-kolom yang lebih rendah. Model struktur dengan link memiliki gaya geser dasar akibat gempa lebih rendah, namun simpangannya lebih besar. Nilai rasio maximum drift terhadap tinggi total struktur akibat empat gempa yang ditinjau memiliki nilai rasio lebih kecil 0,010 sehingga taraf kinerja struktur adalah immediate occupancy.

Response Modification Factor of RC Frames Strengthened with RC Haunches

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.

Optimization of the Dampers Position in High Rise Building

In India the need of high-rise buildings are increasing day by day and it is being constructed also but most of them has common issue of low natural damping. So, increasing capacity of damping of a structural system has become common in the new generationfhighrisebuilding.Itcanbe controlledby variousmeans but selecting damper has a number of factors as efficiency, capital cost, operating cost, compactness and weight, maintenance requirements and safety. In this presentstudy analysis of anR.Cframed high-rise building of 15 storey located in seismic zone V and soil type III having plan dimension 24 m x 25 m and the total height is 45 m is assigned with dampers at different positions (a) building without damper (b) building with dampers at face corner (c) building with dampers at face Centre (d) building with dampers at inner corner (e) building withdampersatinnerCentre is carried out.Theparameterslike roof displacement, storey drift, base shear, ultimate displacement, ductility factorand patternofhinge formationwere investigated and resultswere compared. Itisobserved thatthemodelwithdampers atinnerCentrehasless roof displacement and storey drift as compared to other models whereas the model with dampers at inner corner has more base shear, ultimate displacement and ductility factor. Above analysis is done inEtabs.

Fragility Analysis of Concrete-Filled Steel Tubular Frame Structures with BRBs under Multiple Earthquakes Considering Strain Rate Effects

The fragility of concrete-filled steel tubular (CFST) frame structures with buckling-restrained braces (BRBs) subjected to multiple earthquakes is studied in this paper. First, a fiber beam element model with rate-dependent concrete and steel material properties is developed for CFST members and, then, the effect of the strain rate on the seismic response of the CFST frame structure is investigated numerically. The influence of BRBs on the seismic response of the CFST frame structure is then comparatively analyzed. The seismic responses of the CFST frame structure with BRBs under single mainshocks and earthquake sequences are investigated, and the fragility curves are generated using probabilistic seismic demand analysis. The obtained roof displacement and inter-story drift ratio (ISDR) of the structure decreased by 10.2% and 6.9%, respectively, when obtained while considering the strain rate effect, compared with those obtained without consideration of the strain rate effect. BRBs can effectively improve the seismic performance of the CFST frame structure in that the maximum roof displacement and ISDR can be reduced by 45.1% and 43.9%, respectively. Compared with those under single mainshocks, the maximum roof displacement and ISDR of the structure with BRBs under earthquake sequences significantly increase. The fragility of the BRB structure under earthquake sequences is more severe than that under single mainshocks. Therefore, the influences of the strain rate effect and earthquake sequence should be considered to realistically evaluate the seismic fragility of CFST structures.

Nonlinear Behavior of Flat Slab using Shear Wall

Flat slab is a reinforced concrete slab supported directly by concrete columns without the use of beams .However; in multi-storey buildings it has weak resistance to the lateral loads. Hence this work is concerned to decrease the damage under lateral loading and to minimize the displacement. Shear wall are used to provide stability to structures from lateral loads. The aim of the present study is to analyze effect of shear wall and perimeter beam for flat slab building, and also effectiveness of core shear wall. For present work five models are studied 1) conventional slab building 2) simple flat slab building considered without any drop and column head 3) flat slab with drop building is considered without column head 4) flat slab with drop with perimeter beam building 5) flat slab with perimeter beam and shear wall buildings, each of plan size 25mX25m are selected. For stabilization of structural parameters, shear wall are provided. The seismic parametric studies comprise of roof displacement, base shear, and sequence of hinge formation .from study it concluded that the shear walls significantly increases the base shear capacity and reduces roof displacement and also getting good Performance