The effect of element strength assignment on the torsional response of stiffness-eccentric systems

2013 ◽  
Vol 40 (7) ◽  
pp. 655-662
Author(s):  
George K. Georgoussis
Keyword(s):  
Structural Design ◽  
Shear Force ◽  
Ground Motions ◽  
Building Structures ◽  
Centre Of Mass ◽  
Base Shear ◽  
Structural Behaviour ◽  
Torsional Response ◽  
Building Models ◽  
Storey Building

Building structures of low or medium height are usually designed with a pseudostatic approach using a base shear much lower than that predicted from an elastic spectrum. Given this shear force, the objective of this paper is to evaluate the effect of the element strength assignment (as determined by several building codes) on the torsional response of inelastic single-storey eccentric structures and to provide guidelines for minimizing this structural behaviour. It is demonstrated that the expected torque about the centre of mass (CM) may be, with equal probability, positive (counterclockwise) or negative (clockwise). This result means that the torsional strength should also be provided in equal terms in both rotational directions, and therefore the base shear and torque (BST) surface of a given system must be symmetrical (or approximately symmetrical). In stiffness-eccentric systems, appropriate BST surfaces may be obtained when a structural design is based on a pair of design eccentricities in a symmetrical order about CM, and this is shown in representative single-storey building models under characteristic ground motions.

scholarly journals EFFICIENT THREE-DIMENSIONAL MODELLING OF HIGH-RISE BUILDING STRUCTURES

2013 ◽  
Vol 19 (6) ◽  
pp. 811-822 ◽  
Author(s):  
Mohammed Jameel ◽  
A. B. M. Saiful Islam ◽  
Mohammed Khaleel ◽  
Aslam Amirahmad
Keyword(s):  
Three Dimensional ◽  
Shear Walls ◽  
Shear Wall ◽  
Frame Structure ◽  
Building Structures ◽  
Structural Behaviour ◽  
High Rise ◽  
Structural Responses ◽  
Wall Openings ◽  
Storey Building

A multi-storey building is habitually modelled as a frame structure which neglects the shear wall/slab openings along with the inclusion of staircases. Furthermore, the structural strength provided by shear walls and slabs is not precisely incorporated. With increasing building height, the effect of lateral loads on a high-rise structure increases substantially. Inclusion of shear walls and slabs with the frame leads to improved lateral stiffness. Besides, their openings may play imperative role in the structural behaviour of such buildings. In this study, 61 multi-storey building configurations have been modelled. Corresponding analyses are performed to cope with the influence of shear walls, slabs, wall openings, masonry walls and staircases in addition to frame modelling. The finite element approach is used in modelling and analysis. Structural responses in each elemental combination are evaluated through equivalent static and free vibration analyses. The assessment reveals that inclusion of only slab components with frame modelling contributes trivial improvement on structural performance. Conversely, the presence of shear wall slabs with frame improves the performance noticeably. Increasing wall openings decreases the structural responses. Furthermore, it is not recommended to model staircases in addition to frame–slab–shear wall modelling, unless the effect of wall openings and slab openings is adequately considered.

Combined seismic base shear and torsional loading provisions in the 1990 edition of the National Building Code of Canada

1991 ◽  
Vol 18 (6) ◽  
pp. 945-953
Author(s):  
A. M. Chandler
Keyword(s):  
Ground Motions ◽  
Building Code ◽  
Soil Conditions ◽  
Building Structures ◽  
Base Shear ◽  
Ground Acceleration ◽  
Period Range ◽  
Natural Period ◽  
Short Period ◽  
Edge Response

This paper evaluates the earthquake-resistant design provisions of the 1990 edition of the National Building Code of Canada (NBCC 1990) for asymmetric building structures subjected to combined lateral shear and torsional dynamic loadings arising from earthquake base excitation. A detailed parametric study is presented, evaluating the dynamic edge displacement response in the elastic range, for the side of the building which is adversely affected by lateral–torsional coupling. A series of buildings is studied, with realistic ranges of the fundamental natural period, structural eccentricity, and uncoupled frequency ratio. These buildings are evaluated under base loadings arising from a total of 45 strong motion records taken from earthquakes in North America, Mexico, Europe, the Middle East, and Southern Pacific, categorized according to site soil conditions and the ratio a/v of peak ground acceleration to velocity. The latter parameter together with the uncoupled lateral period are found to influence strongly the combined dynamic edge response, with the greatest forces on edge members arising from earthquakes with high a/v ratio in structures with natural periods below 0.8 s. In this case the NBCC 1990 loading provisions significantly underestimate the elastic dynamic response. For buildings with periods longer than 0.8 s, the conservatism of the base shear provisions leads to overestimation of combined dynamic edge response in asymmetric systems, and this is also true in the short-period range for buildings subjected to ground motions with low a/v ratio. The NBCC 1990 provisions are reasonably conservative for short-period systems subjected to ground motions with intermediate a/v ratio. Key words: earthquakes, seismic, design, response, spectra, base, shear, torsional, provisions.

scholarly journals Modelling and Analysis of Irregular Geometrical Configured RCC Multi-Storey Building Using Shear Wall

10.29007/7bqt ◽  
2018 ◽  
Author(s):  
Rutvij Kadakia ◽  
Vatsal Patel ◽  
Anshu Arya Arya
Keyword(s):  
Carrying Capacity ◽  
Lateral Displacement ◽  
Shear Wall ◽  
Lateral Load ◽  
Load Carrying Capacity ◽  
Base Shear ◽  
Building Models ◽  
Load Carrying ◽  
G 14 ◽  
Storey Building

This study aims to model and study G+14 RCC building with different geometrical configurations and provision of shear wall at different location for zone IV and V. The various parameters like Lateral displacement, Storey drift, Drift ratio, Base Shear are compared for building models developed by using SAP2000 with and without shear wall. The provision of shear wall in multistoried building in zone V improved lateral load carrying capacity and also other parameters are enhanced in comparison with building in zone IV.

scholarly journals Force Based Design and Direct Displacement Based Design for Dual System Structure

2019 ◽  
Vol 19 (3) ◽  
pp. 162
Author(s):  
Annisaa Dina Puspita ◽  
Anis Rosyidah
Keyword(s):  
Shear Force ◽  
Damage Control ◽  
Performance Level ◽  
Dual System ◽  
Reinforcement Ratio ◽  
System Structure ◽  
Building Structures ◽  
Base Shear ◽  
Direct Displacement Based Design ◽  
Displacement Based

The Force Based Design (FBD) and the Direct Displacement-Based Design (DDBD) are methods for designing seismic-resistant buildings. Building structures designed, are expected to be suitable with the purpose and usefulness of a building. For this reason, this study compares the performance of dual system structures using the DDBD and FBD methods that aim to prove better performance with consideration of safety against users during an earthquake. This research method uses design analysis method to compare the value of the base shear force, reinforcement ratio, and performance level using software for static nonlinear pushover analysis. The results showed the value of the base shear force x direction of the DDBD method was 17.57% smaller than the FBD method, whereas for the y direction the DDBD value was greater than 9.38% of the FBD. The value of the reinforcement ratio of the beam, column and shear wall results is greater DDBD than FBD. The actual drift of the DDBD and FBD methods is slightly different. So that both are at the same level of performance, namely damage control. The performance level has not reached the performance target of life safety design in DDBD, but the structure has met the level performance requirements for offices.

Influence of site amplification of seismic ground motions on forces in building structures

1991 ◽  
Vol 18 (6) ◽  
pp. 964-973
Author(s):  
A. C. Heidebrecht ◽  
P. Henderson ◽  
N. Naumoski ◽  
J. W. Pappin
Keyword(s):  
Site Response ◽  
Ground Motions ◽  
Site Amplification ◽  
Building Structures ◽  
Base Shear ◽  
Design Code ◽  
Seismic Design Code ◽  
Soil Site ◽  
Response Amplification ◽  
Different Characteristics

The results for nine sites with different characteristics subjected to earthquakes of varying intensity and frequency content are presented in the form of base shear coefficients, base shear coefficient ratios (surface to rock), and foundation factors. They indicate that large amplifications can be expected at structural periods close to the site periods, especially for low intensity excitation. Comparisons are made with the provisions of the National Building Code of Canada (NBCC) 1990. They show that, depending on the site and the nature and level of the excitation, the expected base shear can be well in excess of the values specified by the NBCC. Key words: seismic, design, code, soil, site, response, amplification, base, shear.

scholarly journals Impact of Variation in Plan Configuration on Structural Behaviour of Reinforced Concrete Building

2021 ◽  
Vol 9 (VIII) ◽  
pp. 495-505
Author(s):  
Akshit Kumar Ketanbhai Ravat
Keyword(s):  
Reinforced Concrete ◽  
Aspect Ratio ◽  
Population Increase ◽  
Centre Of Mass ◽  
Base Shear ◽  
Structural Behaviour ◽  
High Rise ◽  
Concrete Building ◽  
Structural Engineers ◽  
Day By Day

Nowadays high rise building is a new trend in India because day by day population increase and it’s a problem to accommodate large number of people in small place. To resolve this problem only one option is good which is vertical growth of building. Due to architectural purpose some building’s plan like L, C, E and + etc. cause plan irregularities and in elevation like vertical set-back type building cause vertical irregularities. These kind of shapes are creating problem for structural engineers because it demands serious damage in earthquake. In this study the main objective is to understand demand of lateral load on different plan aspect ratio and with varying heights of 18, 33 and 48meter. Modelling of varying heights OF 18, 33 and 48 meter R.C.C. framed building is done on the ETABS software for analysis. Post analysis of the structure, Centre of mass, Centre of resistance of building, maximum storey displacement, storey drift and base shear are computed and then compared for all the analyzed cases.

scholarly journals Parametric Characterization and Analysis of Pounding Behavior Adjacent Multi-Storied Buildings of Varying Heights

2021 ◽  
Vol 9 (10) ◽  
pp. 1048-1057
Author(s):  
Sudhir Kumar
Keyword(s):  
Response Spectrum ◽  
Time Base ◽  
Seismic Gap ◽  
Building Structures ◽  
Analysis Method ◽  
Base Shear ◽  
Severe Damage ◽  
Building Models ◽  
Adjacent Building ◽  
G 12

Abstract: Many past earthquake studies show that during strong vibrations, the adjacent building structures which are closely spaced to each other are vulnerable to severe damage when the adjacent buildings are not at an adequate distance to accommodate their relative displacements. The primary goal of this research is to find out the minimum separation gap between buildings of varying height at the same floor-to-floor height level. SAP 2000 software is used to analyze the structural behavior of building during the earthquake.Three building models are taken for the study, one is six floors (G+6) and another two are nine floors (G+9), and twelve floors (G+12) respectively. Six floors (G+6)& twelve floors (G+12) structures have the same floor to floor height and plan and same beam and column size (equal stiffness) and G+9 buildings have floor to floor height are same but different beam and column sizes (different stiffness). The linear dynamic (RSA) analysis method is used to calculate the response (Displacement, frequency at fundamental time, Base Shear) of the structure at different floors levels. Response (top story displacements) calculated from the response spectrum is compared with the provisions of seismic gap per story height given in IS 4326: 2005.

Torsional motion of buildings during earthquakes. I. Elastic response

1998 ◽  
Vol 25 (5) ◽  
pp. 898-916 ◽  
Author(s):  
J L Humar ◽  
P Kumar
Keyword(s):  
Good Practice ◽  
The Other ◽  
Elastic Response ◽  
Earthquake Response ◽  
Torsional Motion ◽  
Torsional Response ◽  
A Value ◽  
Earthquake Motion ◽  
Building Models ◽  
Storey Building

Analytical studies are carried out on the elastic torsional response of single- and multi-storey building models subjected to earthquake motion. Effects of both the natural and accidental torsion are considered. The results of analysis are compared with the design provisions of the National Building Code of Canada (NBCC). It is shown that the NBCC provisions for the design of resisting elements on the flexible side are overly conservative. On the other hand, provisions for the design of elements on the stiff side are conservative in some situations and inadequate in others. Modifications to the design provisions are suggested which give design forces closer to the results obtained from a dynamic analysis, and are at the same time simpler than the existing provisions. It is shown that the ratio of the uncoupled torsional and translational frequencies is an important parameter governing the torsional response and it would be a good practice in design to achieve a value greater than 1 for this ratio.Key words: earthquake response, natural torsion, accidental torsion, elastic torsional response, design for torsion.

scholarly journals Analisis Perpindahan Lateral Struktur Beton Bertulang Pada Bangunan Bertingkat Beraturan dan Ketidak Beraturan Horizontal

2020 ◽  
Vol 3 (1) ◽  
pp. 19
Author(s):  
Jawarta Simamora ◽  
Leonardus Setia Budi Wibowo ◽  
Didik Purwanto ◽  
Norman Ray
Keyword(s):  
Type A ◽  
Building Structures ◽  
Type B ◽  
Base Shear ◽  
Drift Ratio ◽  
Building Models ◽  
Percentage Difference ◽  
Irregular Buildings ◽  
Load Intensity ◽  
Structural Irregularities

The effect of earthquake forces on buildings will certainly be different if applied to regular and irregular buildings. The performance of structures produced in irregular buildings will be different from the performance of irregular building structures for the same load intensity. In the earthquake resistant structure planning regulations, SNI 1726-2012 concerning structural irregularities. Where in this regulation there are two types of structural irregularities namely horizontal structural irregularities and vertical structural irregularities which are then subdivided into several types of irregularity. The study was carried out to compare the results of building structure performance with horizontal irregularity compared to regular buildings as seen from displacement, drift ratio, base shear, performance level based on ATC-40, differences in reinforcement weight. This research resulted in the largest displacement for the x-direction, namely the type A irregular building where it experiences a deviation of 0,49 m difference and for the y-direction of 0,44 m in the type A irregular building Type A. The biggest drift ratio of the x-direction and direction y is a Type B irregular building that is equal to 0,64 m for the x-direction and 0.57 m for the y-direction. The largest base shear occurs in regular buildings with Type B irregular buildings at 16.34%. the level of performance based on ATC-40 for all building models is immidiate occupancy, the biggest reinforcement need is the irregular building model B with a percentage difference of 11,20%.

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