Predicting the peak structural displacement preventing pounding of buildings during earthquakes

Abstract The aim of the present paper is to verify the effectiveness of the artificial neural network (ANN) in predicting the peak lateral displacement of multi-story building during earthquakes, based on the peak ground acceleration (PGA) and building parameters. For the purpose of the study, the lumped-mass multi-degree-of-freedom structural model and different earthquake records have been considered. Firstly, values of stories mass and stories stiffness have been selected and building vibration period has been automatically calculated. The ANN algorithm has been used to determine the limitation of the peak lateral displacement of the multi-story building with different properties (height of stories, number of stories, mass of stories, stiffness of stories and building vibration period) exposed to earthquakes with various PGA. Then, the investigation has been focused on critical distance between two adjacent buildings so as to prevent their pounding during earthquakes. The proposed ANN has logically predicted the limitation of the peak lateral displacement for the five-story building with different properties. The results of the study clearly indicate that the algorithm is also capable to properly predict the peak lateral dis-placements for two buildings so as to prevent their pounding under different earthquakes. Subsequently, calculation of critical distance can also be optimized to save the land and provide the safety space between two adjacent buildings prone to seismic excitations.

Download Full-text

An ANN-Based Approach for Prediction of Sufficient Seismic Gap between Adjacent Buildings Prone to Earthquake-Induced Pounding

Applied Sciences ◽

10.3390/app10103591 ◽

2020 ◽

Vol 10 (10) ◽

pp. 3591

Author(s):

Seyed Mohammad Khatami ◽

Hosein Naderpour ◽

Seyed Mohammad Nazem Razavi ◽

Rui Carneiro Barros ◽

Barbara Sołtysik ◽

...

Keyword(s):

Parametric Analysis ◽

Structural Parameters ◽

Seismic Gap ◽

Minimal Distance ◽

Lumped Mass ◽

Seismic Excitations ◽

Ground Acceleration ◽

Earthquake Records ◽

Adjacent Buildings ◽

Structural Arrangements

Earthquake-induced structural pounding may cause major damages to structures, and therefore it should be prevented. This study is focused on using an artificial neural network (ANN) method to determine the sufficient seismic gap in order to avoid collisions between two adjacent buildings during seismic excitations. Six lumped mass models of structures with a different number of stories (from one to six) have been considered in the study. The earthquake characteristics and the parameters of buildings have been defined as inputs in the ANN analysis. The required seismic gap preventing pounding has been firstly determined for specified structural arrangements and earthquake records. In order to validate the method for other structural parameters, the study has been further extended for buildings with different values of height, mass, and stiffness of each story. Finally, the parametric analysis has been conducted for various earthquakes scaled to different values of the peak ground acceleration (PGA). The results of the verification and validation analyses indicate that the determined seismic gaps are large enough to prevent structural collisions, and they are just appropriate for all different structural arrangements, seismic excitations, and structural parameters. The results of the parametric analysis show that the increase in the PGA of earthquake records leads to a substantial, nearly uniform, increase in the required seismic gap between structures. The above conclusions clearly indicate that the ANN method can be successfully used to determine the minimal distance between two adjacent buildings preventing their collisions during different seismic excitations.

Download Full-text

Study on Methods to Control Interstory Deflections

Geosciences ◽

10.3390/geosciences10020075 ◽

2020 ◽

Vol 10 (2) ◽

pp. 75 ◽

Cited By ~ 4

Author(s):

Seyed Mohammad Khatami ◽

Hosein Naderpour ◽

Seyed Mohammad Nazem Razavi ◽

Rui Carneiro Barros ◽

Anna Jakubczyk-Gałczyńska ◽

...

Keyword(s):

Base Isolation ◽

Lateral Displacement ◽

Separation Distance ◽

Lumped Mass ◽

Seismic Excitations ◽

Mass Model ◽

Adjacent Structures ◽

Depth Analysis ◽

Lumped Mass Model ◽

Story Building

One of the possibilities to prevent building pounding between two adjacent structures is to consider appropriate in-between separation distance. Another approach might be focused on controlling the relative displacements during seismic excitations. Although the majority of building codes around the world recommend the use of some equations of various distances between structures to avoid pounding; a lot of reports after earthquakes have obviously shown that safety situation or economic consideration is not always provided due to the collisions between buildings and high cost of land; respectively. The aim of the present paper is to focus the analysis on the properties of structures and conduct an in-depth analysis of available methods to control interstory deflections so as to prevent pounding. For this purpose, a numerical lumped mass model of the five-story building has been considered and its response under different earthquake records has been investigated. Firstly, the influence of the change in structural properties (story stiffness; mass and damping) has been examined. Then the application of tuned mass damper, base isolation and base isolation with rubber bumpers has been considered. The results of comparative analyses clearly indicate that using base isolation, with the addition of bumpers, can be selected as the best method to control building deflections and decrease absolute lateral displacement between two buildings so as to prevent their pounding during earthquakes

Download Full-text

Parametric effect of vertical ground acceleration on the earthquake response of elastic structures

Canadian Journal of Civil Engineering ◽

10.1139/l90-026 ◽

1990 ◽

Vol 17 (2) ◽

pp. 209-217 ◽

Cited By ~ 3

Author(s):

S. T. Ariaratnam ◽

K. C. K. Leung

Keyword(s):

Ground Motion ◽

Structural Model ◽

Lateral Displacement ◽

Stochastic Modelling ◽

Tall Building ◽

Earthquake Excitation ◽

Restoring Force ◽

Ground Acceleration ◽

Linear Elastic ◽

Vertical Ground

An analytical procedure is presented for the calculation of the statistical properties of the response of a linear elastic tall building under earthquake excitation. Emphasis is placed on the effect of the vertical ground motion. The restoring force in each story of the structural model is assumed to arise from the bending deformation of the columns whose rigidities are subjected to a general reduction due to the combined action of gravitational forces and the random variations due to vertical ground acceleration. Since earthquakes are random phenomena, stochastic modelling of ground motion seems appropriate. Both the vertical and the horizontal accelerations are treated as amplitude-modulated Gaussian random processes. With these models, the techniques developed herein, using the concept of Markov processes and Itô's stochastic differential equations, may be applied. To illustrate the application of the method, numerical results are presented for a six-story building. For computational purposes, the structural properties are evaluated using the finite element method. Within the limit of linear elastic deformation, the vertical ground acceleration is shown to be capable of causing only a slight increase of 0.08% in the lateral displacement for this moderately tall building. The percentage is expected to be larger for a taller building and much larger when the deformations exceed the elastic limit. Key words: earthquake excitation, elastic frames, random vibration, Markov process, dynamic response.

Download Full-text

Critical distance between two irregular adjacent buildings in order to prevent collision during earthquake

Journal of Engineering Research ◽

10.36909/jer.13929 ◽

2021 ◽

Author(s):

Yaghub Ebrahimi ◽

◽

Ali Hemmati ◽

Ali Reza Mortezaei ◽

Mahmud Nikkhah Shahmirzadi ◽

...

Keyword(s):

Neural Network ◽

Lateral Displacement ◽

Critical Distance ◽

Gap Size ◽

Story Model ◽

Adjacent Buildings ◽

Mathematical Equations ◽

Lateral Displacements ◽

The Impact ◽

Tabas Earthquake

The aim of this study is to evaluate the value of suitable distance due to prevent the impact between two irregular adjacent buildings when earthquake is caused to occur large lateral displacement and damage the elements of buildings. For this purpose, by using a mathematical program based on neural network, the number of stories, the period and height of investigated models, PGD, PGV and PGA of earthquake records are defined and the nonlinear lateral displacements of different structures are determined in order to use in the program. Thus, the results of displacements based on all inputs are listed and the minimum critical distance is approximately estimated based on especial regression. For instance, a 3-4 story model is numerically investigated by Tabas earthquake record, which is suggested to provide required gap size about 70 cm. In fact, each model has to observe a 35 cm gap. A newly developed program based on mathematical equations are applied for determining the lateral displacements of each story. A new mathematical formula is proposed by neural network, which shows the least distance between irregular adjacent buildings. For investigating the accuracy of formula, two different ways are performed and the results of analyses confirm suggested equation. For this challenge, a 2-4 story model is considered and three different critical distances are calculated to be 59, 62 and 75 cm which show the last gap size is able to provide safety gap size, determined by suggested formula.

Download Full-text

Damage-Involved Structural Pounding in Bridges under Seismic Excitation

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.754.309 ◽

2017 ◽

Vol 754 ◽

pp. 309-312 ◽

Cited By ~ 2

Author(s):

Robert Jankowski

Keyword(s):

Structural Damage ◽

Structural Model ◽

Viscoelastic Model ◽

Time History ◽

Seismic Wave Propagation ◽

Seismic Excitation ◽

Lumped Mass ◽

Positive Role ◽

Contact Points ◽

Elevated Bridge

During severe earthquakes, pounding between adjacent superstructure segments of highway elevated bridges was often observed. It is usually caused by the seismic wave propagation effect and may lead to significant damage. The aim of the present paper is to show the results of the numerical analysis focused on damage-involved pounding between neighbouring decks of an elevated bridge under seismic excitation. The analysis was carried out using a lumped mass structural model with every deck element discretized as a SDOF system. Pounding was simulated by the use of impact elements which become active when contact is detected. The linear viscoelastic model of collision was applied allowing for dissipation of energy due to damage at the contact points of colliding deck elements. The results show that pounding may substantially modify the behaviour of the analysed elevated bridge. It may increase the structural response or play a positive role, and the response depends on pattern of collisions between deck elements. The results also indicate that a number of impacts for a small in-between gap size is large, whereas the value of peak pounding force is low. On the other hand, the pounding force time history for large gap values shows only a few collisions, but the value of peak pounding force is substantially large, what may intensify structural damage.

Download Full-text

Analysis of Mistuned Blade Vibrations Based on Normally Distributed Blade Individual Natural Frequencies

Volume 7B: Structures and Dynamics ◽

10.1115/gt2015-43121 ◽

2015 ◽

Cited By ~ 4

Author(s):

Felix Figaschewsky ◽

Arnold Kühhorn

Keyword(s):

Probability Distribution ◽

Development Process ◽

Structural Model ◽

Natural Frequencies ◽

Rotor Blades ◽

Lumped Mass ◽

Mass Model ◽

Influence Coefficients ◽

Random Mistuning ◽

Rotor Assembly

With increasing demands for reliability of modern turbomachinery blades the quantification of uncertainty and its impact on the designed product has become an important part of the development process. This paper aims to contribute to an improved approximation of expected vibration amplitudes of a mistuned rotor assembly under certain assumptions on the probability distribution of the blade’s natural frequencies. A previously widely used lumped mass model is employed to represent the vibrational behavior of a cyclic symmetric structure. Aerodynamic coupling of the blades is considered based on the concept of influence coefficients leading to individual damping of the traveling wave modes. The natural frequencies of individual rotor blades are assumed to be normal distributed and the required variance could be estimated due to experiences with the applied manufacturing process. Under these conditions it is possible to derive the probability distribution of the off-diagonal terms in the mistuned equations of motions, that are responsible for the coupling of different circumferential modes. Knowing these distributions recent limits on the maximum attainable mistuned vibration amplitude are improved. The improvement is achieved due to the fact, that the maximum amplification depends on the mistuning strength. This improved limit can be used in the development process, as it could partly replace probabilistic studies with surrogate models of reduced order. The obtained results are verified with numerical simulations of the underlying structural model with random mistuning patterns based on a normal distribution of individual blade frequencies.

Download Full-text

Influence of Multiple Openings on Reinforced Concrete Outrigger Walls in a Tall Building

Applied Sciences ◽

10.3390/app9224913 ◽

2019 ◽

Vol 9 (22) ◽

pp. 4913 ◽

Cited By ~ 2

Author(s):

Han-Soo Kim ◽

Yi-Tao Huang ◽

Hui-Jing Jin

Keyword(s):

Reinforced Concrete ◽

Structural Model ◽

Lateral Displacement ◽

Tall Buildings ◽

Structural Performance ◽

Element Analysis ◽

Wall Area ◽

Strut And Tie ◽

Equivalent Bending Stiffness ◽

Strut And Tie Model

Outrigger systems have been used to control the lateral displacement of tall buildings. Reinforced concrete (R.C.) outrigger walls with openings can be used to replace conventional steel outrigger trusses. In this paper, a structural model for an R.C. outrigger wall with multiple openings was proposed, and the effects of the multiple openings on the stiffness and strength of the outrigger walls were evaluated. The equivalent bending stiffness of the outrigger wall was derived to predict the lateral displacement at the top of tall buildings and internal shear force developed in the wall. The openings for the passageway in the wall were designed by the strut-and-tie model. The stiffness and strength of the outrigger wall with multiple openings was analyzed by the nonlinear finite element analysis. Taking into consideration the degradation in stiffness and strength, the ratio of the opening area to the outrigger wall area is recommended to be less than 20%. The degradation of stiffness due to openings does not affect the structural performance of the outrigger system when the outrigger has already large stiffness as the case of reinforced concrete outrigger walls.

Download Full-text

Identification of Sudden Stiffness Change in the Acceleration Response of a Nonlinear Hysteretic Structure

Shock and Vibration ◽

10.1155/2020/3824216 ◽

2020 ◽

Vol 2020 ◽

pp. 1-20

Author(s):

Sheng-Lan Ma ◽

Shao-Fei Jiang ◽

Chen Wu ◽

Si-Yao Wu

Keyword(s):

Structural Model ◽

Dynamic Responses ◽

Physical Parameters ◽

Discrete Wavelet ◽

Time Varying ◽

Ground Acceleration ◽

Structural Dynamic ◽

Filter Tuning ◽

Structural Responses ◽

Extent Of Damage

The integration of discrete wavelet transform and independent component analysis (DWT-ICA) method can directly identify time-varying changes in linear structures. However, better metrics of structural seismic damage and future performance after an event are related to structural permanent and total plastic deformations. This study proposes a two-stage technique based on DWT-FastICA and improved multiparticle swarm coevolution optimization (IMPSCO) using a baseline nonlinear Bouc–Wen structural model to directly identify changes in stiffness caused by damage as well as plastic or permanent deflections. In the first stage, the measured structural dynamic responses are preprocessed firstly by DWT, and then the Fast ICA is used to extract the feature components that contain the damage information for the purpose of initially locating damage. In the second stage, the structural responses are divided at the identified damage instant into segments that are used to identify the time-varying physical parameters by using the IMPSCO, and the location and extent of damage can accordingly be identified accurately. The efficiency of the proposed method in identifying stiffness changes is assessed under different ground motions using a suite of two different ground acceleration records. Meanwhile, the effect of noise level and damage extent on the proposed method is also analyzed. The results show that in a realistic scenario with fixed filter tuning parameters, the proposed approach identifies stiffness changes within 1.25% of true stiffness within 8.96 s; therefore, it can work in real time. Parameters are identified within 14% of the actual as-modeled value using noisy simulation-derived structural responses. This indicates that, in accordance with different demands, the proposed method can not only locate and quantify damage within a short time with a high precision but also has excellent noise tolerance, robustness, and practicality.

Download Full-text

Inelastic Deformation of One-Story Asymmetric-Plan Systems Subjected to Strong Earthquake Ground Motions

Earthquake Spectra ◽

10.1193/1.1585797 ◽

1994 ◽

Vol 10 (4) ◽

pp. 777-790 ◽

Cited By ~ 1

Author(s):

Masakazu Ozaki ◽

Tatsuya Azuhata ◽

Toru Takahashi ◽

M. Shaomei

Keyword(s):

Strong Earthquake ◽

Ground Motions ◽

System Response ◽

Vibration Period ◽

Torsional Strength ◽

Inelastic Response ◽

Earthquake Ground Motions ◽

Strength Capacity ◽

Building Systems ◽

Story Building

Inelastic response of one-story building systems with eccentricity is investigated based on linear static and nonlinear dynamic analyses using asymmetric-plan systems simultaneously subjected to strong earthquake ground motions in the x- and y-directions. Inelastic story drift ratios in the x- and y-directions are evaluated considering shear and torsional strength capacity and the corresponding shear force and torsional moment acting in each direction of asymmetric-plan system. Response analysis of one-story systems with one-axis plan asymmetry and varying parameters such as uncoupled lateral vibration period, torsion-to-lateral frequency ratio, rigidity and strength eccentricities, and shear and torsional strength capacity ratio is carried out and compared with those of corresponding one-story symmetric systems. In addition, inelastic response of one-story building systems with two-axes eccentricity including a L-shape asymmetric-plan system is also investigated.

Download Full-text