Design Implications of Structural Irregularity

2002 ◽  
Author(s):  
Wenshen Pong ◽  
David Nesbet
Keyword(s):  
Dynamic Analysis ◽  
Dynamic Performance ◽  
Regular Structure ◽  
Lateral Force ◽  
Seismic Zone ◽  
Base Shear ◽  
Structural Engineer ◽  
Seismic Forces ◽  
Structural Engineers ◽  
Building Designs

Irregular building designs present special problems to the structural engineer due to their uneven distributions of mass, stiffness, and strength. Because of these factors, irregular structures may have significantly different dynamic performance than a regular structure, which can lead to unanticipated force concentrations, deflections, and subsequent stresses on building members. Irregular building designs, while often more visually and architecturally interesting, are significantly more challenging to engineer for seismic loads. Discontinuities and irregularities in mass, configuration, and form can create many unwanted and unexpected effects when a structure is subjected to seismic forces. The Uniform Building Code (UBC) 1997 edition has addressed this concern by requiring dynamic analysis of irregular building designs greater than five stories in areas with greater seismic activity (seismic zones 3 and 4). The UBC’s requirement of a dynamic lateral force analysis, along with the requirement of a higher base shear force for irregular building designs (regular buildings are given a 10% base shear reduction bonus when dynamic analysis is performed), has made irregular building designs unattractive to structural engineers. Some structural engineers may question whether the UBC provisions are unnecessarily punitive to irregular building analysis, particularly for smaller buildings. To test this hypothesis, this study compares the results of using much simpler static seismic loading analysis with the results obtained from a dynamic analysis on two steel-frame six-story irregular building designs. The first building is irregular due to a type 3 vertical geometric irregularity (specifically a 3-story tower asymmetrically located above the remaining 3 stories). The second building is irregular due to a plan structural irregularity (a large central courtyard which creates diaphragm discontinuities in the top three stories). Both buildings are considered to be located in seismic zone 4, with a forcing input based on the 1997 UBC figure 16-3 used for the dynamic analysis. This study aims to present the design implications of structural irregularity. It seeks to investigate the differences in the calculated seismic forces, deflections, and stresses due to the two different methods of analysis.

scholarly journals Backstay Effect of Diaphragm in Tall Building

2020 ◽  
Vol 9 (3) ◽  
pp. 1578-1587
Keyword(s):  
Seismic Analysis ◽  
Response Spectrum ◽  
Retaining Wall ◽  
Tall Building ◽  
Structural Systems ◽  
Base Shear ◽  
High Rise ◽  
Structural Engineer ◽  
Structural Responses ◽  
Seismic Forces

Seismic analysis of structural systems with floor diaphragms has been a requisite in the recent past. The duty of a structural engineer is to be prudent about the behavior of every structural system adopted. Amongst the structural systems that are adopted world over, diaphragm with rigid and semi-rigid floor plate are adopted widely in the analysis. This research focuses on the backstay effect i.e. podium structural interaction with the tower area and consideration of retaining wall as increment of lateral stiffness as specified in latest tall building code IS6700:2016 for low and high rise structures. In the current study models were prepared with low to high rise storeys with rigid and flexible diaphragms considering backstay diaphragm placing tower at center and corner. The models were subjected to seismic forces; response spectrum along with the combination of the gravity loads. The structural responses like natural periods, base shear, displacement and inter storey drift were also studied.

scholarly journals Shear Walls Induced RC Structures

2021 ◽  
Vol 12 (2) ◽  
pp. 1827-1834
Author(s):  
Kesava Rao B, Et. al.
Keyword(s):  
Dynamic Analysis ◽  
Response Spectrum ◽  
Pushover Analysis ◽  
Shear Walls ◽  
Shear Wall ◽  
Lateral Force ◽  
Wind Pressure ◽  
Earthquake Response ◽  
Rc Structures ◽  
Seismic Forces

In recent years, the construction of skyscrapers has been on the rise to overcome the shortage of land. These buildings are subject to an external lateral force, such as an earthquake and wind pressure. Pushover analysis (POA) has been broadly used in predicting the earthquake response of structures, and shear walls have been shown to be lateral drag elements. Therefore, in the present work, the effect of placing a shear wall on the periphery symmetrically, the periphery asymmetrically and in the center of the building is performed using the ETABS software. Using the response spectrum methodand thetime history method, a dynamic analysis is performed. Responses such as floor shear, floor displacement, and lateral floor shifts due to seismic forces are evaluated for various locations of the shear wall. According to the results and analysis, the shear wall on the symmetrical periphery of the structure is reducing the displacement and deviation of the floor compared to other cases.

scholarly journals Effects of Beam Members on Performance of Buildings under Seismic Forces

2019 ◽  
Vol 8 (3) ◽  
pp. 7797-7803
Keyword(s):  
Reinforced Concrete ◽  
Seismic Analysis ◽  
Lateral Force ◽  
Seismic Zone ◽  
Response Factors ◽  
Cross Sectional ◽  
Force System ◽  
Beam Elements ◽  
Time Period ◽  
Seismic Forces

The main aim of the paper is to present an analysis to study on non-linear seismic analysis of reinforced concrete (RC) framed buildings as per the provisions of Indian code IS1893-2016 to evaluate the response of the building configurations depending upon the section sizes of the horizontal members; beams and as per variation in its cross-sectional area. The response of buildings has been noted in terms of quantities as the time period of buildings.Indian seismic code IS 1893 has been employed for the design provisions of the seismic analysis and the structures have been evaluated for seismic zone II. The design software STAAD.Pro has been used for the dynamic analysis.The response of the structure under lateral force system, induced due to seismic activities is must be analysed to understand the behaviour of structure under dynamic forces. The paper evaluates the most common but important response factors of the structure which are most important in the design of building. The paper also shows the detailed results of the time period of buildings for various building configuration. The evaluated results have been tabulated and analysed with the help of a comparative study of the obtained data. The work is useful for better understanding of the performance of the reinforced concrete buildings as per the different sizes and sections and stiffness of the beam elements.

scholarly journals Analysis of L-Shape Building with Lift Core at Different Locations And Its Torsional Effect

2020 ◽  
Vol 2 (1) ◽  
pp. 1-10
Author(s):  
Sushil Adhikari ◽  
Tek Bahadur Katuwal ◽  
Dipak Thapa ◽  
Suraj Lamichhane ◽  
Dhurba Adhikari
Keyword(s):  
Response Spectrum ◽  
Seismic Zone ◽  
Base Shear ◽  
Response Spectrum Analysis ◽  
Outer Corner ◽  
Drift Ratio ◽  
Time Period ◽  
Natural Time ◽  
Structural Responses ◽  
Seismic Forces

 In L-shape building, lift core wall is an important element for strengthening the structure of high seismic zone area. Seismic zone V is considered for most of the buildings in Nepal, which will cause maximum base shear to the structure. This study focuses the use of lift core in five and ten-storey building to resist the seismic forces, and the effect of the lift core is also taken into consideration. Based on the location of the lift core, these building are further subdivided into different models; Lift at outer corner (model 1), lift at lower edge corner (model 2), lift at upper edge corner (model 3), lift at lower and upper edge corner (model 4), lift at inner corner (model 5), and lift at inner and outer corner (model 6). Equivalent static method and response spectrum analysis was used for the analysis. The structural responses were measured in terms of modal periods, displacement, drift ratio, and torsional irregularities. Results from this study indicate that building with lift core wall at inner and outer (model 6) and lift at lower and upper edge corner (model 4) shows the minimum drift ratio, torsional irregularities, displacement and natural time period which lies within permissible limit of torsional irregularities. Hence, it can be concluded that the location of the lift core affects the torsion of an L-shape plan asymmetric building. Designing two lift core at the inner and outer corner (model 6) and lower and upper edge corner (model 4) is found to be effective in reducing the torsion.

Measured natural periods of concrete shear wall buildings: insights for the design of Canadian buildings

2012 ◽  
Vol 39 (8) ◽  
pp. 867-877 ◽  
Author(s):  
Damien Gilles ◽  
Ghyslaine McClure
Keyword(s):  
Seismic Analysis ◽  
Dynamic Properties ◽  
Response Spectrum ◽  
Shear Wall ◽  
Mode Shapes ◽  
Design Stage ◽  
Base Shear ◽  
Period Equation ◽  
Input Load ◽  
Structural Engineers

Structural engineers routinely use rational dynamic analysis methods for the seismic analysis of buildings. In linear analysis based on modal superposition or response spectrum approaches, the overall response of a structure (for instance, base shear or inter-storey drift) is obtained by combining the responses in several vibration modes. These modal responses depend on the input load, but also on the dynamic characteristics of the building, such as its natural periods, mode shapes, and damping. At the design stage, engineers can only predict the natural periods using eigenvalue analysis of structural models or empirical equations provided in building codes. However, once a building is constructed, it is possible to measure more precisely its dynamic properties using a variety of in situ dynamic tests. In this paper, we use ambient motions recorded in 27 reinforced concrete shear wall (RCSW) buildings in Montréal to examine how various empirical models to predict the natural periods of RCSW buildings compare to the periods measured in actual buildings under ambient loading conditions. We show that a model in which the fundamental period of RCSW buildings varies linearly with building height would be a significant improvement over the period equation proposed in the 2010 National Building Code of Canada. Models to predict the natural periods of the first two torsion modes and second sway modes are also presented, along with their uncertainty.

scholarly journals Dynamic Analysis for VSG-Based Power Flow Control Applied to DG Systems

2021 ◽  
Author(s):  
THIAGO FIGUEIREDO DO NASCIMENTO ◽  
ANDRES ORTIZ SALAZAR
Keyword(s):  
Power Systems ◽  
Dynamic Analysis ◽  
Power Flow ◽  
Control Strategies ◽  
Renewable Energy Sources ◽  
Dynamic Performance ◽  
Synchronous Generator ◽  
Power Flow Control ◽  
Grid Impedance ◽  
Impedance Parameters

The integration of distributed generation (DG) systems based on renewable energy sources (RES) by using power converters is an emerging technology in modern power systems. Among the control strategies applied to this new configuration, the virtual synchronous generator (VSG) approach has proven to be an attractive solution due providing suitable dynamic performance. Thus, this paper presents a dynamic analysis of gridtied converters controlled by using VSG concept. This analysis is based on a dynamic model that describes the DG power flow transient characteristics. Based on this model, the grid impedance parameters variation effects on the VSG controllers dynamic performance are discussed. Simulation results are presented to evaluate the effectiveness of the theoretical analysis performed.

scholarly journals Dynamic Analysis on RCC and Composite Structure for Uniform and Optimized Section

2021 ◽  
Vol 9 (12) ◽  
pp. 1114-1127
Author(s):  
Ankit Kumar
Keyword(s):  
Dynamic Analysis ◽  
Composite Structure ◽  
Composite Structures ◽  
Response Spectrum ◽  
Steel Structures ◽  
Seismic Zone ◽  
Dead Weight ◽  
Conventional Concrete ◽  
High Rise ◽  
Time Period

Abstract: This study examines the composite structure that is increasing commonly in developing countries. For medium-rise to high-rise building construction, RCC structures is no longer economical due to heavy dead weight, limited span, low natural frequency and hazardous formwork. The majority of commercial buildings are designed and constructed with reinforced concrete, which largely depends on the existence of the constituent materials as well as the quality of the necessary construction skills, and including the usefulness of design standards. Conventional RCC structure is not preferred nowadays for high rise structure. However, composite construction, is a recent development in the construction industry. Concrete-steel composite structures are now very popular due to some outstanding advantages over conventional concrete and steel structures. In the present work, RCC and steel-concrete composite structure are being considered for a Dynamic analysis of a G+25-storey commercial building of uniform and optimized section, located at in seismic zone IV. Response Spectrum analysis method is used to analyze RCC and composite structure, CSI ETABS v19 software is used and various results are compared such as time period, maximum storey displacement, maximum storey stiffness. Maximum storey shear and maximum stoey overturning moment. Keywords: RCC Structure, Composite Structure, Uniform Section, Optimized Section, Shear Connector, Time Period, Storey Displacement, Storey Shear, Storey Stiffness, Response Spectrum method, ETABS

The Force Analysis of Anchor Anti-Slide Pile in Slope Reinforcement under Seismic Load

2015 ◽  
Vol 777 ◽  
pp. 148-153
Author(s):  
Hui Ding ◽  
Jie Chen ◽  
Li Song
Keyword(s):  
Dynamic Analysis ◽  
Seismic Wave ◽  
Contact Stress ◽  
Dynamic Performance ◽  
Bending Moment ◽  
Dynamic Contact ◽  
Design Parameters ◽  
Seismic Load ◽  
Slope Reinforcement ◽  
Earthquake Action

The force affect factors of anchor anti-slide pile in slope reinforcement under seismic load are studied in this paper. First of all, the method of dynamic analysis is introduced in FLAC3D. At the same time, seismic wave is selected in seismic dynamic analysis. Then, the sensitivity influence of anti-slide pile design parameters on dynamic contact stress, shear force and dynamic bending moment is analyzed by applying the seismic wave, giving the most significant effect factors of the dynamic contact stress and dynamic moment. In the end, the distribution regular of the contact force and the pile body stress under earthquake action is analyzed by selecting a case, laying a theoretical foundation for the further study of the dynamic performance of the reinforced slope.

scholarly journals Structural model and dynamic analysis of six-axis Cartesian coordinate robot for sheet metal bending

2019 ◽  
Vol 16 (4) ◽  
pp. 172988141986156
Author(s):  
Fengyu Xu ◽  
Quansheng Jiang ◽  
Lina Rong ◽  
Pengfei Zhou ◽  
Jinlong Hu
Keyword(s):  
Dynamic Analysis ◽  
Sheet Metal ◽  
Laboratory Testing ◽  
Structural Model ◽  
Dynamic Performance ◽  
Work Conditions ◽  
Structure Model ◽  
Sheet Metal Bending ◽  
Cartesian Coordinate ◽  
The Stability

Bending is an important procedure for processing sheet metals, while it is a key link in the realization of automatic processing of sheet metal. To improve the efficiency and accuracy of bending processing, this article proposed a structure model and a prototype of a six-axis Cartesian coordinate robot for sheet metal bending to replace workers completing automatic bending processes. Based on the analysis of overall structure schemes of the robot, kinematic simulation is conducted by using the automatic dynamic analysis of mechanical system (ADAMS). Furthermore, the dynamic performance of the structural model of the robot for sheet metal bending is analysed and design optimization is performed. A prototype of the robot based on the optimal structural model of six-axis Cartesian coordinate robot for sheet metal bending is made. Finally, under the work conditions, the efficiencies and accuracies of sheet metal bending by a worker and the robot are compared and tested. The structural model of six-axis Cartesian coordinate robot for sheet metal bending presented in this article is found to be applicable to sheet metal bending robot and improves the stability of sheet metal bending machine. The laboratory testing and experimental results verified the feasibility of the proposed robot.

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