Author: Y. Richard Kim | Size: 61.9 MB | Format:PDF | Quality:Unspecified | Publisher: CRC Press | Year: 2014 | pages: 1966 | ISBN: 113802693X
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MITIGATION OF SEISMIC POUNDING BETWEEN ADJACENT BUILDINGS
Author: A. Hameed, M. Saleem, A.U. Qazi, S. Saeed* and M. A. Bashir | Size: 661 KB | Format:PDF | Quality:Unspecified | Publisher: Pakistan Journal of Science (Vol. 64 No. 4 December, 2012) | Year: 2012 | pages: 08
Adjacent buildings during an earthquake may collide against each other when, owing to their different dynamic characteristics, the buildings vibrate out of phase and the at-rest separation distance is inadequate to accommodate their relative motions. Seismic pounding can cause severe damage to the structures. Such buildings are usually separated by an expansion joint which is insufficient to accommodate the lateral movements of buildings under earthquakes. While seismic pounding can be prevented by providing adequate safe code specified separation distances, sometimes getting of required safe separations is not possible in metropolitan areas because buildings are built very close to each other due to high land value, limited availability of land space, the need for centralized facilities under one roof and/or often ignoring the likelihood of seismic pounding between adjacent buildings during design. If building separations in metropolitan areas found to be deficient to prevent pounding, then there should be some secure and cost-effective retrofitting methods to mitigate
structural pounding. This research work covers the mitigation techniques of pounding between adjacent buildings due to earthquakes. Use of shear wall, bracing system and friction dampers are proposed as possible mitigation techniques.
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Author: R. Shafiei-Tehrany, M. ElGawady*, W. Coffer | Size: 872 KB | Format:PDF | Quality:Unspecified | Publisher: Electronic Journal of Struct ural Engineering 11(1) 2011 | Year: 2011 | pages: 10
Nonlinear pushover analysis is a powerful tool for evaluating the inelastic seismic behavior of structures. This paper presents a detailed seismic analysis of a complex bridge. The I-5 Ravenna Bridge was assessed through nonlinear pushover analyses that highlights many important issues of bridges constructed on hollow core prestressed concrete piles. A three dimensional finite element analysis of the bridge have been carried out including modeling of the bridge bearings, expansions joints, and soil-structure interaction. The nonlinear response of the bridge was investigated from the first pier hinging to the inelastic equilibrium condition using three different response spectrums representing ground motions with different return periods. The effects on the seismic demand due to period lengthening and damping increase produced by structural deterioration were evaluated. The effects of three different soils on the bridge performance were investigated as well. Using dense sand increased the stiffness of the system and the ductility capacity. In addition, change the soil type has insignificant effect on the post-yielding stiffness of the bridge
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Development of pounding model for adjacent structures in earthquakes
Author: S. Khatiwada, N. Chouw and J.W. Butterworth Department of Civil and Environmental Engineering, University of Auckland, New Zealand | Size: 394 KB | Format:PDF | Quality:Unspecified | Publisher: Proceedings of the Ninth Pacific Conference on Earthquake Engineering Building an Earthquake-Resilient Society 14-16 April, 2011, Auckland, New Zealand | Year: 2011 | pages: 08
Building pounding, a frequently recurrent problem in strong earthquakes,
occurs when there is inadequate separation between adjacent structures. Several models have been proposed for the calculation of the resultant impact force, and its effect on the participating structures. This study analyzes two impact models, viz. the elastoplastic impact model by van Mier et al and the nonlinear viscoelastic impact element proposed by Jankowski and proposes a new impact model. The proposed viscous elastoplastic impact element combines all three properties of viscosity, elasticity and plasticity in an impact element for the first time. The plastic effect may be due to the material yielding at the contact location of the participating structures. A sample numerical investigation is presented for the seismic pounding between two adjacent buildings due to the 1940 North South El-Centro ground motions. The results show that the time history of the roof displacement of the participating structures is significantly different and the maximum displacement is reduced when the new model is employed when compared to the results obtained from numerical simulations using a nonlinear viscoelastic impact element.
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Pounding Effects on Bridge s during Extreme Earthquakes
Author: Tzu-Ying Lee 1, Kai-Tien Chen 1, Chun-Chuan Su 1 1Department of Civil Engineering, National Central University, No.300, Jhongda Road, Jhongli, Taiwan | Size: 486 KB | Format:PDF | Quality:Unspecified | Publisher: Proceedings of the 8th International Conference on Structural Dynamics, EURODYN 2011 Leuven, Belgium, 4-6 July 2011 G. De Roeck, G. Degrande, G. Lombaert, G. M¨uller (eds.) | Year: 2011 | pages: 06 | ISBN: 978-90-760-1931-4
In the past extreme earthquakes, a number of bridges suffered damage with unseating of superstructures.
Whenever unseating failure occurs, local cracking or crushing due to pounding between superstructures can be observed in the
sites. Therefore, this paper is aimed to study pounding effect on isolated bridges in ultimate situation through numerical analysis.
The Vector Form Intrinsic Finite Element (VFIFE) is superior in managing the engineering problems with material nonlinearity,
discontinuity, large deformation, large displacement and arbitrary rigid body motions of deformable bodies. The VFIFE is thus
selected to be the analysis method in this study. Since the VFIFE is in its infant stage of development, there are still a number of
elements to be developed. Three types of impact models are developed for VFIFE to simulate the pounding effect. The
developed impact elements are verified to be accurate by a model comprising two SDOF systems. Two adjacent single-span
isolated bridges are then analyzed to study the pounding effect under extreme earthquakes. The results show insignificant
difference of the pounding effect by any impact model with or without energy dissipation. It is interesting to observe that the
column ductility demand remains identical regardless of the strength of unseating prevention device. The larger the mass ratio of
the two adjacent decks, the larger the intensity of the ground motion the column reaches its ultimate ductility.
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POUNDING OF ADJACENT RC BUILDINGS DURING SEISMIC LOADS
Author: Mizam DOĞAN1, Ayten GÜNAYDIN2 | Size: 1.7 MB | Format:PDF | Quality:Unspecified | Publisher: Journal of Engineering and Architecture Faculty of Eskişehir Osmangazi University, Vol: XXII, No:1, 2009 | Year: 2009 | pages: 17
Turkey is in high seismic risk zone. On a possible earthquake, adjacent buildings which are not separated from each other properly are under pounding risk. Although gap size requirements are given in Turkish Earthquake Code (TEC), in Turkey, adjacent buildings are still been constructing with insufficient gap sizes. In this paper; results of pounding and effects of pounding to structural elements of buildings are studied. Stress analyses are made on frame models for different impact points and analysis results are discussed. It is concluded that pounding forces are not completely absorbable because of their high values but their effects on structure can be reduced by placing elastic materials between adjacent buildings or by reinforcing structural systems with cast-in-place reinforced concrete (RC) walls
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Pounding between base-isolated and fixed-base RC buildings during earthquakes
Author: Deepak Raj Pant, Anil C. Wijeyewickrema Department of Civil and Environmental Engineering, Tokyo Institute of Technology, Japan | Size: 438 KB | Format:PDF | Quality:Unspecified | Publisher: Proceedings of the 8th International Conference on Structural Dynamics, EURODYN 2011 Leuven, Belgium, 4-6 July 2011 G. De Roeck, G. Degrande, G. Lombaert, G. M¨uller (eds.) | Year: 2011 | pages: 07 | ISBN: 978-90-760-1931-4
Pounding of base-isolated buildings during earthquakes could have detrimental effects on the performance of such buildings. Most previous studies on seismic pounding of base-isolated buildings have been carried out using simplified lumped mass numerical models. However, these simplified models cannot incorporate the nonlinear properties of realistic building materials such as reinforced concrete (RC). Therefore, the response of a base-isolated RC building during pounding with an adjacent structure is not well understood. Owing to the increasing use of base-isolation technology for seismic protection of mid-rise RC buildings around the world, it is important to study seismic pounding response of such buildings. This paperinvestigates the seismic pounding of a typical 4-story base-isolated RC building with 4-story and 8-story fixed-base RC buildings. Three-dimensional numerical models with due consideration of material and geometric nonlinearities are developed. Performance of the base-isolated building is evaluated in terms of story drift, story shear and overall damage index. It is foundthat the pounding of the base-isolated building with the 4-story fixed-base building is more critical than the pounding with the 8- story fixed-base building. The findings of the study are expected to assist design and evaluation of typical mid-rise baseisolated RC buildings.
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Lightweight, high-strength materials are used to construct flexible, long-span floors. These floors sometimes result in annoying levels of vibration even under ordinary loading
situations. These vibrations do not possess any threat to the structural integrity of the floor, but they may render the floor unusable by the human occupants of the building in extreme cases.
The wide variety of scales and prediction techniques is an indication of the complex nature of floor vibrations. The increasing incidence of building vibration due to human
rhythmic activities led to a specific design criterion for rhythmic excitations (Allen et al. 1985,Bachmann and Ammann, 1987,Faisca, 2003,Murray et al., 2003, Silva et al.,
2008). Floor vibrations often leads to structural failure as demonstrated by the Hyatt Regency Hotel Walkway in Kansas city, US, (McGrath and Foote, 1981) and London Millennium Footbridge (BBC news, 2000 and Sample, 2002).This is the motivation for the development of a design methodology on the structural system subjected to dynamic loads due to human activities. But, it is very difficult to interpret the magnitude of the motion, the environment surrounding sensor and the human sensor in accounting the floor vibrations
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Development of a numerical model for the prediction of ground-borne noise and vibration in buildings
Author: Péter F IALA M.Sc.E.E | Size: 5.2 MB | Format:PDF | Quality:Unspecified | Year: 2008 | pages: 128
Significant vibration in buildings near surface or underground railway tracks or roads is attributed to moving vehicles. Traffic induced vibrations in dense urban environments can cause structural damage in buildings and annoyance to the inhabitants of surrounding buildings in the form of vibrations or re-radiated noise.The vibrations within a building have several effect on the building’s structure. The vibrations can vary in a large range from imperceptible to levels causing structural damage. The limit above which the vibrations damage the structure is not clear. Some authors claim
that traffic induced ground-borne vibrations can not damage the structures and at worst disturb the occupants. Others [Cro65], however, state that the damaging effect of low frequency vibrations is cumulative and causes the uneven soil settlement under buildings over a long
time period.
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Now nearing its 30th year of publication, WELDING: PRINCIPLES & APPLICATIONS (WP&A), 7th Edition is the authoritative introduction to the subject of welding. It's designed for students in a wide range of academic and workforce training programs who want to pursue careers as skilled welders and welding supervisors.
The text also supports the needs of learners who need to achieve a basic level of proficiency in welding in their chosen skilled trade. While covering the procedural and safety information all students need, WELDING: PRINCIPLES & APPLICATIONS also explains underlying theories. The combination of hands-on information with clear explanations of theory is a hallmark of this book. The depth of coverage allows it to be used as the core text in a multi-course welding curriculum, generally starting with shielded metal arc welding, and then covering other basic processes and more advanced techniques.
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