Pounding Of Buildings Research Articles

Effect of Earthquake-Induced Structural Pounding on the Floor Accelerations and Floor Response Spectra of Adjacent Building Structures

The influence of earthquake-induced structural pounding among buildings is paramount in the seismic analysis and design of structures. The recognition of such a phenomenon has been growing in the last decades. The search for ways to understand and mitigate the consequences of these structural collisions in building structures is the primary goal of the investigation of earthquake-induced building pounding. This phenomenon is known for increasing the floor accelerations, mainly where pounding occurs, implying significant local damage. These collisions cause short-duration acceleration pulses that may compromise the building structure and the non-structural elements within the building’s stories. Non-structural elements supported by the structure’s floors under earthquake-induced pounding instances may present a risk to human lives and/or human activity. Hence, the influence of earthquake-induced pounding in the floor response spectra of two adjacent reinforced concrete structures with inelastic behavior is assessed by varying the number of stories and their separation distance. Pounding greatly influenced the floor acceleration spectra, increasing the spread of accelerations over a broader period range, particularly exciting low to moderate periods of vibration.

Experimental and numerical studies of seismic induced story-to-story and inter-story pounding

Pounding between adjacent buildings was repeatedly observed during many major earthquakes. Previous studies on building pounding are mainly based on the analytical and numerical investigations. A few experimental studies were reported, but these studies mainly focused on the story-to-story pounding, which is not necessarily the case in engineering practices. When the story heights of two adjacent buildings are different, inter-story pounding occurs. Moreover, most buildings have irregular shapes, which may result in the eccentric poundings. Few experimental studies have been performed to understand the combined inter-story and eccentric poundings between adjacent buildings yet. This paper presents the experimental studies on the seismic pounding between adjacent multi-story buildings. Shaking table tests on three 1/3 scaled 2-story and 3-story buildings were performed to understand their behaviors when they were subjected to the earthquake ground motions. The story-to-story pounding, inter-story pounding, and eccentric pounding are experimentally investigated and the results are presented and analyzed in this paper. Then a detail 3D FE model is developed and validated by experiment data. The effect of mass eccentricity on inter-story pounding is analyzed by the numerical model. The experimental and numerical results show that, pounding can induce much higher frequency contents to the structural responses compared to the case without pounding, and the pounding forces in the story-to-story pounding case are larger than those in the inter-story pounding case; mass eccentricity has obvious influence on the base share force and displacement response of the building.

Analysis of floor-to-column pounding of buildings founded on different soil types

The aim of this study is to investigate the effect of the soil type on buildings experiencing floor-to-column pounding during earthquakes. Five buildings with 4-storeys, 6-storeys, and 7-storeys were considered. Three types of the 4-storey building with different total heights were taken into account which leads to floor-to-column pounding at 1/3, 1/2 and 2/3 of the height of the impacted column. Two pounding scenarios were considered, i.e. pounding between the 4-storey and 6-storey buildings (three cases when collisions occur at 1/3, 1/2 and 2/3 of the height of the impacted column) and pounding between the 4-storey and 7-storey buildings (three cases when collisions occur at 1/3, 1/2 and 2/3 of the height of the impacted column). In the first part of this study, the shear demands of the columns at the contact area were studied and compared with the no pounding case to investigate the effect of the floor-to-column pounding. Then, the shear demands of the columns at the contact area were studied for buildings founded on different soil types to investigate the effect of the soil type on the structural response. The results of this study illustrate that the shear demands of the impacted column significantly increase due to collisions and it exceeds the shear strength in all cases. Moreover, impacted column experiences higher shear demands for buildings founded on the soft clay soil, then for buildings founded on the stiff soil, then for buildings founded on very dense soil and soft rock, and finally for buildings founded on the rock and hard rock.

Predicting the peak structural displacement preventing pounding of buildings during earthquakes

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.

Modelling of earthquake-induced pounding between adjacent structures with a non-smooth contact dynamics method

This article presents the kinematic analysis of two adjacent structures with pounding using the framework of finite element dynamic analysis and a non-smooth contact dynamics (NSCD) method for treating contact-impact. The latter consists of a Moreau-Jean implicit integration scheme that uses Moreau’s sweeping process and Newton’s impact law. Test cases are carried out to prove the efficiency of the implementation and accuracy of the results relative to the widely used penalty method (PM). Furthermore, finite element simulations are compared with shaking table results of two structures susceptible to pounding. Models are steel frames 2.5 m to 5 m high, 3 m in span, have reinforced-concrete slabs, and distant 0 to 5 cm. Floor displacements, number and time of occurrence of impacts, as well as shape of the response spectra are in good agreement with experimental observations. Moreover, using the building pounding frame and the NSCD method, an estimation of a constant value for the coefficient of restitution was carried out. It is concluded that the NSCD method is a very numerically efficient tool in terms of reduction of CPU time and description of the impact physics. Consequently, this approach is amenable for fragility analysis of the dynamic response of structures involving a contact-impact phenomenon.

Study on Methods to Control Interstory Deflections

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

Damage‐based seismic planar pounding analysis of adjacent symmetric buildings considering inelastic structure–soil–structure interaction

SummaryIn cities and urban areas, building structures located at close proximities inevitably interact under dynamic loading by direct pounding and indirectly through the underlying soil. Majority of the previous adjacent building pounding studies that have taken the structure–soil–structure interaction (SSSI) problem into account have used simple lumped mass–spring–dashpot models under plane strain conditions. In this research, the problem of SSSI‐included pounding problem of two adjacent symmetric in plan buildings resting on a soft soil profile excited by uniaxial earthquake loadings is investigated. To this end, a series of SSSI models considering one‐directional nonlinear impact elements between adjacent co‐planar stories and using a method for direct finite element modeling of 3D inelastic underlying soil volume has been developed to accurately study the problem. An advanced inelastic structural behavior parameter, the seismic damage index, has been considered in this study as the key nonlinear structural response of adjacent buildings. Based on the results of SSSI and fixed base case analyses presented herein, two main problems are investigated, namely, the minimum building separation distance for pounding prevention and seismic pounding effects on structural damage in adjacent buildings. The final results show that at least three times, the International Building Code 2009 minimum distance for building separation recommended value is required as a clear distance for adjacent symmetric buildings to prevent the occurrence of seismic pounding. At the International Building Code‐recommended distance, adjacent buildings experienced severe seismic pounding and therefore significant variations in storey shear forces and damage indices. Copyright © 2016 John Wiley & Sons, Ltd.

2011 Sikkim Earthquake at Eastern Himalayas: Lessons learnt from performance of structures

On 18 September 2011, all the Indian states and countries surrounding Sikkim witnessed a devastating moderate earthquake of magnitude 6.9 (Mw). Originating in Sikkim–Nepal border with an intensity of VI+ in MSK scale, this earthquake caused collapse of both unreinforced masonry buildings, heritage structures and framed structures followed by landslides and mud slides at various places of Sikkim. Significant damages have been observed in relatively new framed structures mainly in Government buildings, thick masonry structures, while, the older wooden frame (ekra) non-engineered structures performed well during the earthquake. Further, it is noteworthy that government buildings suffered more than private ones and damages were observed more in newer framed structures than older ones. Analysis of the damages identify lateral spreading of slope, pounding of buildings, out-of-plane rotation, generation of structural cracks, plastic hinge formation at column capitals and damage of infill wall material as predominant damage features. A few remedial measures are also attempted to be mentioned with future need of research and application. It has been felt to create awareness regarding these issues and is the need of the hour.

Limitations in Simulation of Building Pounding in Earthquakes

Several methods have been proposed for the analysis of building pounding. In previous studies some of these models have been considered in isolation, while others have been studied as a specific configuration of buildings. Although the pounding force predicted by each model varies significantly, results from the evaluation of these models have been inconclusive. This leads to uncertainties in the practical applications of pounding force models. This study addresses the limitations in numerical and experimental simulations of building pounding. The Sears impact model is suggested to overcome some of these limitations. It is concluded that contact stiffness and coefficient of restitution are the main reason for the diverse numerical results, while differences observed in the experiments could be due to sampling rate and instrumental constraints.

An efficient methodology for simulating earthquake‐induced 3D pounding of buildings

SUMMARYThe current paper presents an efficient methodology for numerically simulating in three dimensions adjacent buildings that may experience pounding during strong earthquakes. In particular, a new approach to the numerical problem of spatial impact modeling that does not require the ‘a priori’ determination of the contact points is presented, taking also into account the geometry at the vicinity of an impact. In the current study, the buildings are simulated as linear multi‐degree‐of‐freedom‐systems, but the methodology can be easily extended to consider nonlinear behavior as well. A software application has been specifically developed to implement the proposed methodology, using modern object‐oriented design and programming. The developed software is utilized in a simple example, and the computed results are compared with the corresponding analysis results obtained from a commercial general‐purpose software application that uses typical contact elements for the simulation of impacts. A discussion follows on the advantages and capabilities of the proposed methodology and the developed software. Copyright © 2013 John Wiley & Sons, Ltd.

A shake table investigation on interaction between buildings in a row

Pounding damage has been observed frequently in major earthquakes in the form of aesthetic, minor or major structural cracks and collapse of buildings. Studies have identified a building located at one end of a row of buildings as very vulnerable to pounding damage, while buildings in the interior of the same row are assumed to be safer. This study presents the results of a shake table investigation of pounding between two and three buildings in a row. Two steel portal frames, one stiffer and another more flexible, were subjected to pounding against a frame with eight other configurations. Three pounding arrangements were considered, i.e., the reference frame (1) on the right of the second frame, (2) in the middle of two identical frames, and (3) on the right of two identical frames. Zero seismic gap was adopted for all tests. Five different ground motions are applied from both directions (right to left and left to right). The amplification of the maximum deflection due to pounding was calculated for each configuration. The results showed that, for the stiffer building in a row, row building pounding is more hazardous than pounding between only two buildings. The location of the stiffer frame, whether at the end or the middle of the row, did not have much effect on the degree of amplification observed. Additionally, for all cases considered, pounding caused less amplification for stronger ground motions, i.e., the ground motions that produced higher maximum deflection without pounding than other ground motions.

Influence of Seismic Pounding on RC Buildings with and without Base Isolation System Subject to Near-Fault Ground Motions

Building pounding occurs between two adjacent buildings with small gap or without sufficient separation distance. It leads to damage buildings during earthquake due to impact. Many researchers have investigated building pounding based on impact force reduction and energy dissipation increase, when two buildings collide with each other. In numerical investigations, using specific link element, impact force is calculated in order to get the proper evaluation of damage for preventing failure of structural elements. In this paper, focusing on numerical investigation, the effectiveness of impact and energy dissipation is studied. For this challenge, two RC structural models are considered to evaluate the pounding to calculate the impact force and finally, to compare the effectiveness of Base Isolation (BI) support against fixed support. A link element is located at the connection level between two studied dynamic models.

Utilization of object-oriented programming, design patterns and java for simulating earthquake-induced poundings of base-isolated buildings

Base-isolated buildings experience large horizontal relative displacements during strong earthquakes due to the excessive fl exibility that is purposely incorporated, through seismic bearings, at their bases. When the available clearance around a base-isolated building is limited, there is a possibility of the building pounding against the surrounding moat wall or adjacent structures. Considering the nonlinearities involved in this structural impact problem, it is evident that the effects of potential pounding on the overall seismic response of base-isolated buildings during earthquake excitations should be investigated numerically through appropriate simulations. Object-oriented programming (OOP), design patterns (DPs), and the Java programming language have been utilized in order to design and implement a fl exible and extendable software application that can be effectively used to perform the necessary numerical simulations and parametric studies of base-isolated buildings that may experience structural poundings during earthquake excitations. The aim of this paper is twofold: (i) to explain the signifi cant advantages of utilizing OOP, DPs, and Java in structural analysis software and (ii) to use the developed software to study earthquake-induced poundings of base-isolated buildings.

Building pounding damage observed in the 2011 Christchurch earthquake

SUMMARYBuilding pounding damages observed in the February 2011 Christchurch earthquake are described in this paper. The extent and severity of pounding damage is presented based on a street survey of Christchurch's central business district. Six damage severity levels and two confidence levels are defined to classify the observed damage. Generally, pounding was observed to be a secondary effect. However, over 6% of the total surveyed buildings were observed to have significant or greater pounding damage. Examples of typical and exceptional pounding damage are identified and discussed. Extensive pounding damage was observed in low‐rise unreinforced masonry buildings that were constructed with no building separation. Modern buildings were also endangered by pounding when building separations were infilled with solid architectural flashings. The damage caused by these flashings was readily preventable. The observed pounding damage is compared to that observed in the September 2010 Darfield earthquake to explore if the damage could have been predicted. It is found that pounding prone buildings can be identified with reasonable accuracy by comparing configurations to characteristics previously noted by researchers. However, detailed pounding damage patterns cannot currently be precisely predicted by these methods. Copyright © 2011 John Wiley & Sons, Ltd.

Pounding of structures modelled as non‐linear impacts of two oscillators

AbstractA new formulation is proposed to model pounding between two adjacent structures, with natural periods T1 and T2 and damping ratios ζ1 and ζ2 under harmonic earthquake excitation, as non‐linear Hertzian impact between two single‐degree‐of‐freedom oscillators. For the case of rigid impacts, a special case of our analytical solution has been given by Davis (‘Pounding of buildings modelled by an impact oscillator’ Earthquake Engineering and Structural Dynamics, 1992; 21:253–274) for an oscillator pounding on a stationary barrier. Our analytical predictions for rigid impacts agree qualitatively with our numerical simulations for non‐rigid impacts. When the difference in natural periods between the two oscillators increases, the impact velocity also increases drastically. The impact velocity spectrum is, however, relatively insensitive to the standoff distance. The maximum relative impact velocity of the coupled system can occur at an excitation period Tn* which is either between those of the two oscillators or less than both of them, depending on the ratios T1/T2 and ζ1/ζ2. Although the pounding force between two oscillators has been primarily modelled by the Hertz contact law, parametric studies show that the maximum relative impact velocity is not very sensitive to changes in the contact parameters. Copyright © 2001 John Wiley & Sons, Ltd.

Building pounding damage during the 1989 Loma Prieta earthquake

This paper presents a survey of building pounding caused by the 1989 Loma Prieta earthquake. Pounding was present over a wide geographical area including the cities of San Francisco, Oakland, Santa Cruz and Watsonville. The survey database contains more than 200 pounding occurrences involving more than 500 building structures. The paper discusses the distribution of pounding damage in the specific areas, types of pounding damage, and examples of pounding damage involving major miltistorey buildings. Some significant pounding occurred at sites with large epicentral distances indicating the possible catastrophic damage that may occur during future earthquakes having closer epicentres.

Analytical prediction of experimental building pounding : A. Filiatrault, P. Wagner & S. Cherry, Earthquake Engineering & Structural Dynamics, 24(8), 1995, pp 1131–1154

Analytical prediction of experimental building pounding : A. Filiatrault, P. Wagner & S. Cherry, Earthquake Engineering & Structural Dynamics, 24(8), 1995, pp 1131–1154

Analytical prediction of experimental building pounding

AbstractValuable insights on the problem of seismic pounding have been obtained recently from analytical studies. So far, the proposed analytical models have not been validated experimentally. This paper presents the results of shake table tests of pounding between adjacent three‐ and eight‐storey single‐bay steel framed model structures. The pounding response of the frames was measured for various earthquake intensities and initial separations. The experimental results were compared to the predictions resulting from two existing pounding analysis programs. The solution strategy of the first program, SLAM‐2, is based on a modal superposition technique. The second program, PC‐ANSR, is a non‐linear time‐step analysis code in which an elastic gap element has been included. Modelling the pounding effect by elastic gap elements in the two programs produced accurate displacement and impact force results. Amplitudes of short acceleration pulses were not well predicted, however, for practical time‐step increments. Relative rotations between adjacent floors induced grinding contacts which cannot be captured by uni‐axial gap elements.

Pounding of buildings during earthquakes: a Canadian perspective : A. Filiatrault, M. Cervantes, B. Folz & H. Prion, Canadian Journal of Civil Engineering, 21(2), 1994, pp 251–265

Pounding of buildings during earthquakes: a Canadian perspective : A. Filiatrault, M. Cervantes, B. Folz & H. Prion, Canadian Journal of Civil Engineering, 21(2), 1994, pp 251–265

Pounding of buildings during earthquakes: a Canadian perspective

The main objective of this paper is to provide information to structural engineers on how to consider and mitigate the phenomenon of pounding between adjacent structures during earthquakes. The first part of the paper reviews the problem of seismic pounding; observations of damage from pounding during recent earthquakes are described as well as the pounding potential for buildings in large Canadian cities. A review of literature on analytical and numerical studies of earthquake pounding is presented along with methods that have been proposed to mitigate pounding. In the second part of the paper, the seismic behaviour of three closely spaced, Canadian code designed, plane steel frames is investigated. Nonlinear time-step dynamic analyses and nonlinear elastic gap elements, to model pounding, are used for this purpose. Several parameters, such as separation distances, pounding locations, and ground motion characteristics, are considered. Key words: dynamics, earthquakes, impacts, pounding, seismic.