scholarly journals Evaluation of seismic forces under modified structural schemes in the process of vibrations

2021 ◽  
Vol 17 (4) ◽  
pp. 391-403
Author(s):  
Yury T. Chernov ◽  
Jaafar Qbaily
Keyword(s):  
Bearing Capacity ◽  
Natural Vibration ◽  
Seismic Analysis ◽  
Dynamic Properties ◽  
Actual Behavior ◽  
Inelastic Behavior ◽  
Time Step ◽  
Design Scheme ◽  
Static Calculation ◽  
Seismic Forces

The aim of the work - development of one of the possible methods for seismic analysis that considers the inelastic behavior of structures under seismic loads. This requires the development of seismic analysis methods that take into account the change (decrease) in the bearing capacity or the destruction of individual elements until the final loss of the bearing capacity of the structure. Methods. The dependences and algorithms include determining seismic forces using the method of normal forms, which until now is the main one in solving problems of the seismic resistance theory in seismic regions, calculation formulas to calculate seismic forces at each time step are presented in the form of expansions into natural vibration modes, which regard the changes in the design scheme. The calculation is repeated at each time step as a static calculation for the action of seismic forces determined at the previous stage, before the building collapses. Results. The developed dependencies and algorithms allow to consider changes in the design scheme during vibrations at each time step, changes in the dynamic properties of the building and, as a result, the values of seismic forces. The value of the coefficient of inelastic work of structures K 1, which are given in regulatory documents, do not give fully correspond to the actual behavior of the structure under seismic influences. The proposed calculation method allows to determine the estimated values of seismic forces and their distribution taking into account the influence of damage of elements and the appearance of inelastic zones in the design process of fluctuations at each time step and to assess the dynamic behavior of the building.

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 A comparative study on a complex URM building: part II—issues on modelling and seismic analysis through continuum and discrete-macroelement models

2021 ◽  
Author(s):  
G. Castellazzi ◽  
B. Pantò ◽  
G. Occhipinti ◽  
D. A. Talledo ◽  
L. Berto ◽  
...  
Keyword(s):  
Seismic Analysis ◽  
Dynamic Properties ◽  
Limit State ◽  
Central Italy ◽  
Nonlinear Static Analysis ◽  
Structural Safety ◽  
Masonry Building ◽  
Maximum Acceleration ◽  
Capacity Curves ◽  
Comparison Of The Results

AbstractThe paper presents the comparison of the results obtained on a masonry building by nonlinear static analysis using different software operating in the field of continuum and discrete-macroelement modeling. The structure is inspired by an actual building, the "P. Capuzi" school in Visso (Macerata, Italy), seriously damaged following the seismic events that affected Central Italy from August 2016 to January 2017. The activity described is part of a wider research program carried out by various units involved in the ReLUIS 2017/2108—Masonry Structures project and having as its object the analysis of benchmark structures for the evaluation of the reliability of software packages. The comparison of analysis was carried out in relation to: global parameters (concerning the dynamic properties, capacity curves and, equivalent bilinear curves), synthetic parameters of structural safety (such as, for example, the maximum acceleration compatible with the life safety limit state) and the response in terms of simulated damage. The results allow for some insights on the use of continuum and discrete-macroelement modeling, with respect to the dispersion of the results and on the potential repercussions in the professional field. This response was also analyzed considering different approaches for the application of loads.

scholarly journals Determination of Period of RC Buildings by the Ambient Vibration Method

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Mehmet Inel ◽  
Hayri Baytan Ozmen ◽  
Bayram Tanik Cayci
Keyword(s):  
Natural Vibration ◽  
Dynamic Properties ◽  
Shear Walls ◽  
Vibration Signal ◽  
Analytical Models ◽  
Ambient Vibration ◽  
Seismic Behaviour ◽  
Infill Wall ◽  
Infill Walls ◽  
Vibration Period

Determining the dynamic properties of structures is important for understanding their seismic behaviour. Ambient vibration signal measurement is one of the approaches used to determine the period of structures. Advantages of this method include the possibility of taking real-time records and presenting nondestructive and rapid solutions. In this study, natural vibration periods are calculated by taking ambient vibration signal records from 40 buildings. The height of the building, infill wall effect, presence of seismic retrofit, and presence of damage are taken into consideration, and their effects on natural vibration periods are investigated. Moreover, the results are compared with the analytical methods to reveal the differences. A significant correlation between the period and height of the building is observed. It is seen that the natural vibration periods of the buildings decrease by 7% to 30% (15% on average) due to infill wall contribution. However, the efficiency of infill walls decreases as the building height increases. Another significant result is that adding shear walls substantially decreases the vibration period values by 23% to 33% with respect to the shear wall ratio. When the analytical estimates and measured building period results are compared, it is seen that analytical models have closer period estimates before infill walls are implemented. The limited data in scope of the study suggest that significant differences may present in the analytical and measured periods of the buildings due to infill wall contributions.

Seismic Analysis of the Single-Layered Cylindrical Grid Shell

2012 ◽  
Vol 166-169 ◽  
pp. 2159-2163 ◽  
Author(s):  
Cheng Shen ◽  
Cheng Wei Huang ◽  
Yong Lin Gao
Keyword(s):  
Seismic Performance ◽  
Seismic Analysis ◽  
Dynamic Properties ◽  
Static Stability ◽  
Spatial Structures ◽  
Long Span ◽  
Light Duty ◽  
Grid Shell ◽  
Cylindrical Grid ◽  
Spatial Grid

Among the long-span spatial structures, the grid shell has many advantages compared to the other spatial structures.Because of the combination of the reasonableness of mechanics and the economy production,and characteristics of the light-duty and the mature design methods,this structure has more wider application than the others.At present,the static stability problem of spatial grid shell structure has been well solved,but the research about dynamic properties and seismic performance is imperfect,especially about single-layered cylindrical grid shell.So this paper does some research about the seismic performance on the base of numerical analysis.

SEISMIC ANALYSIS OF OFFSHORE TRIANGULAR TENSION LEG PLATFORMS

2006 ◽  
Vol 06 (01) ◽  
pp. 97-120 ◽  
Author(s):  
S. CHANDRASEKARAN ◽  
A. K. JAIN ◽  
N. R. CHANDAK
Keyword(s):  
Deep Water ◽  
Seismic Analysis ◽  
Vertical Component ◽  
Vertical Direction ◽  
Gas Production ◽  
Hydrodynamic Drag ◽  
Environmental Loads ◽  
Axial Forces ◽  
Seismic Force ◽  
Seismic Forces

Oil and gas production from deep-water offshore fields represent a major structural engineering challenge for the industry. The tension leg platform (TLP) is a well-established concept for deep-water oil exploration. It is necessary to design an offshore TLP such that it can respond to moderate environmental loads without damage, and is capable of resisting severe environmental loads without seriously endangering the occupants. Seismic analysis of triangular TLP under moderate regular waves is investigated. The analysis considers nonlinearities due to the change in tether tension and nonlinear hydrodynamic drag forces. The coupled response of TLP under moderate regular sea waves due to change in initial pretension in the tethers caused by seismic forces (vertical direction) is then investigated. Seismic forces are imposed at the bottom of each tether as axial forces. The tether tension becomes unbalanced when the hull is under offset position. The vertical component of seismic force is an important item to take into consideration, because it is directly superposed to pretension of tethers. The change in initial pretension due to the vertical component of the earthquake affects the response of the triangular TLP in degrees-of-freedom experiencing such forces. The tether tension varies nonlinearly when the platform is subjected to seismic forces caused by the El Centro earthquake and artificially generated earthquake using Kanai–Tajimi's power spectrum. The response due to earthquakes varies with the intensity of the input ground motion. The seismic response of the triangular TLP exhibits nonlinear behavior in the presence of waves and it is non-proportionately influenced by the wave period and the wave height.

scholarly journals Response Quantities of Framed Buildings under Dynamic Excitation

2019 ◽  
Vol 8 (11) ◽  
pp. 3798-3804
Keyword(s):  
Seismic Analysis ◽  
Structural Response ◽  
Base Shear ◽  
Response Factors ◽  
Analysis And Design ◽  
Dynamic Excitation ◽  
Combination Methods ◽  
Time Period ◽  
Moment Resisting ◽  
Seismic Forces

Seismic analysis of structure is employed to make the structure enable to resist the seismic forces and perform against the factors causing the failure of the structure under dynamic excitation. Among various response factors, the base shear and time period of buildings are predominant factors used in the analysis and design of the structure. The prime objective of the paper is to present an analytical study on non-linear seismic analysis of moment resisting framed buildings (as per Indian code IS1893 – 2016) to evaluate the base shear of different configurations of buildings according to different mode combination methods. The obtained results have been presented the comparative analysis of different combination methods. The paper also presents the evaluated results in the form of the time period values of the different buildings depending upon variation in its configuration. As a result, the responses of multistoried moment-resisting framed buildings have been evaluated for various models of considered buildings based on different mode combination methods, and the results of obtained responses have been analyzed in a comparative manner to understand the behaviour of buildings under various methods and configuration conditions. The work presented in the paper can support to develop better understanding of structural response and efficient designing of structures.

scholarly journals Design and Seismic Analysis of Ground Supported Water Tank

10.29007/gqkl ◽  
2018 ◽  
Author(s):  
Rahul Patel ◽  
Rishi Dave ◽  
Prutha Vyas
Keyword(s):  
Program Analysis ◽  
Seismic Analysis ◽  
Hydrodynamic Pressure ◽  
Water Tank ◽  
Base Shear ◽  
Moment Capacity ◽  
Spreadsheet Program ◽  
Analysis And Design ◽  
Working Stress ◽  
Seismic Forces

The ground supported tanks are firmly attached with ground and tank walls are subjected to hydrostatic as well as hydrodynamic pressure due to seismic forces. Base of the tank is subjected to weight of water and pressure of soil. Top of the tanks may be covered and is designed by using IS 3370:2009 Part (I, II) [4] and IS 1893:2007 (part-2) draft code[3] is used for the seismic analysis of the tank. This paper gives idea behind the design of liquid retaining structure (rectangular ground supported water tank) using working stress method. This paper includes the seismic analysis and design of the tank. The values are obtained with the help of spreadsheet program. Analysis of ground supported water tank has been carried out and relationship between tank capacity with moment capacity and reinforcement area, base shear with impulsive height and overturning moment with convective height is derived.

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 Analysis of Reinforced Concrete Intze Water Tank with Different Staging Heights in Different Seismic Zones

2020 ◽  
Vol 8 (6S) ◽  
pp. 185-190
Keyword(s):  
Water Distribution ◽  
Seismic Analysis ◽  
Hydrodynamic Pressure ◽  
Soil Condition ◽  
Soil Types ◽  
Water Tank ◽  
Seismic Zone ◽  
Lateral Forces ◽  
Seismic Forces ◽  
Water Tanks

RC intze water tanks are constructed for storage and suppling of water through a certain height with adequate pressure of water distribution. Many overhead water tanks affected due to certainty like earthquake that can induce large lateral forces. So, there is a necessity to Understand and examine the behavior of intze tank supported on framing in context to different soil types under the seismic forces. This paper evaluates the experimental output of seismic analysis that compares shear and moments at base and also hydrodynamic pressure at wall and base slab for various seismic zone and different type of soil condition at different staging heights.

scholarly journals Seismic Behavior of RC Intze Water Tank under Various Zone and Soil Condition

2020 ◽  
Vol 9 (3S) ◽  
pp. 22-25
Keyword(s):  
Seismic Behavior ◽  
Water Distribution ◽  
Seismic Analysis ◽  
Soil Condition ◽  
Soil Conditions ◽  
Water Tank ◽  
Seismic Zone ◽  
Zone Ii ◽  
Seismic Forces ◽  
Water Tanks

RC intze water tanks are constructed for storage and suppling of water through a certain height with adequate pressure of water distribution. Many overhead water tanks affected due to certainty like earthquake that can induce large lateral forces. So, there is a necessity to Understand and examine the behavior of intze tank supported on framing in context to different soil types under the seismic forces. This paper evaluates the experimental output of seismic analysis that compares shear and moments at base for different seismic zone (II, III, IV, V) in different type of soil conditions.

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