Design for seismic torsional forces

1984 ◽  
Vol 11 (2) ◽  
pp. 150-163 ◽  
Author(s):  
J. L. Humar

An analytical study of the responses of a single storey and a multistorey building model to a combined translational and rotational ground motion is presented. The models, which are assumed to be elastic, are eccentric about one plan direction but are symmetric about the perpendicular direction. The ground excitations are represented by idealized spectra.A critical evaluation is made of the torsion provisions of the National Building Code of Canada. It is shown that the code provisions, while not necessarily nonconservative, are somewhat difficult to apply for multistorey buildings. An alternative provision for design eccentricity is proposed. The forces obtained by the use of the proposed method are compared with the analytical results of single storey and multistorey building models and are shown to provide an adequate design basis.

1969 ◽  
Vol 59 (4) ◽  
pp. 1495-1515
Author(s):  
Gary C. Hart

Abstract The actual earthquake damage in two high-rise buildings in Bogota, Colombia, is compared with predicted response of four three-dimensional analytic building models. Three building models of the 24-story steel frame Bank of Bogota and one of the 29-story concrete frame Bavaria Office Building are considered. Periods and mode shapes are calculated for each building model. Maximum interstory displacements, absolute roof accelerations, story shears, and torques are calculated in each building model for three well-recorded earthquakes, one being a July 1967 earthquake in Colombia, as recorded at a nearby Bogota seismograph station. In all earthquakes, both components of ground motion were applied simultaneously.


1985 ◽  
Vol 12 (3) ◽  
pp. 583-592 ◽  
Author(s):  
A. Rutenberg ◽  
A. C. Heidebrecht

The primary purpose of this paper is to discuss the separation of travelling wave effects from the mass center to resistance center eccentricity effects, and to propose means by which the torsional spectrum (or a torsional seismic factor) could be incorporated in the seismic provisions of the National Building Code of Canada. The paper begins the treatment of the subject matter by presenting a detailed review of previous work on the effects of torsional ground motion, emphasizing the methods which have been proposed to develop torsional response spectra. The travelling wave assumption is critically reviewed and the effective phase velocities applicable for design purposes are discussed. This is followed by a simple analysis showing how the torsional spectra can be derived directly from the corresponding translational response spectra. Formulae separating the torsional input effects from the accidental eccentricity effects are presented and discussed. Finally, it is shown how the torsional spectrum can be incorporated within the framework of the response spectrum procedure of the 1985 edition of the National Building Code of Canada. Key words: seismic, earthquake, structure, dynamic, rotation, code, torsion, foundation, eccentricity, response spectrum, acceleration, velocity, design.


Geophysics ◽  
2017 ◽  
Vol 82 (5) ◽  
pp. W17-W30 ◽  
Author(s):  
Zhenhua Li ◽  
Mirko van der Baan

Traditionally, seismological interpretations are based on the measurement of only translational motions, such as particle displacement, velocity, and/or acceleration, possibly combined with pressure changes; yet theory indicates that rotational motions should also be observed for a complete description of all ground motions. The recent and ongoing development of rotational sensors renders a full analysis of the translational and rotational ground motion possible. We have developed the basic mathematical theory related to rotational motion. And we also evaluated several instruments used to directly measure the rotational ground motion, which may be applicable for exploration geophysics. Finally, we made several applications of rotational motion in exploration geophysics, namely, (1) P- and S-wavefield separation, (2) wavefield reconstruction, (3) ground-roll removal, (4) microseismic event localization and reflection seismic migration by wavefield extrapolation, and (5) moment tensor inversion. The cited research shows that in particular, the information on the spatial gradient of the wavefield obtained by rotational sensors is beneficial for many purposes. This tutorial is meant to (1) enhance familiarity with the concept of rotational seismology, (2) lead to additional applications, and (3) fast track the continued development of rotational sensors for global and exploration geophysical use.


Author(s):  
Zhenni Wu ◽  
Hengxin Chen ◽  
Bin Fang ◽  
Zihao Li ◽  
Xinrun Chen

With the rapid development of computer technology, building pose estimation combined with Augmented Reality (AR) can play a crucial role in the field of urban planning and architectural design. For example, a virtual building model can be placed into a realistic scenario acquired by a Unmanned Aerial Vehicle (UAV) to visually observe whether the building can integrate well with its surroundings, thus optimizing the design of the building. In the work, we contribute a building dataset for pose estimation named BD3D. To obtain accurate building pose, we use a physical camera which can simulate realistic cameras in Unity3D to simulate UAVs perspective and use virtual building models as objects. We propose a novel neural network that combines MultiBin module with PoseNet architecture to estimate the building pose. Sometimes, the building is symmetry and ambiguity causes its different surfaces to have similar features, making it difficult for CNNs to learn the differential features between the different surfaces. We propose a generalized world coordinate system repositioning strategy to deal with it. We evaluate our network with the strategy on BD3D, and the angle error is reduced to [Formula: see text] from [Formula: see text]. Code and dataset have been made available at: https://github.com/JellyFive/Building-pose-estimation-from-the-perspective-of-UAVs-based-on-CNNs .


2021 ◽  
Author(s):  

Precast, prestressed concrete design is based on conformance with the provisions of the American Concrete Institute’s (ACI’s) Building Code Requirements for Structural Concrete (ACI 318-14) and Commentary (ACI 318R-14). In most cases, these provisions are followed explicitly. Occasionally, interpretation of some sections of ACI 318 is required to ensure quality is maintained in conjunction with the unique characteristics of precast and prestressed concrete fabrication, shipping, and erection. Members of the PCI Building Code Committee, along with other experienced precast concrete design engineers, have identified code provisions, detailed in this publication, that require clarification or interpretation. These design practices are followed by most precast concrete design engineers to produce safe, economical precast concrete structures and they provide a consistent approach for the designers and contractors.


1986 ◽  
Vol 13 (1) ◽  
pp. 46-52 ◽  
Author(s):  
V. W.-T. Cheung ◽  
W. K. Tso

To evaluate the seismic torsional effect on multistory buildings, the concept of eccentricity is extended from single-story buildings to multistory buildings by defining the locations of the centers of rigidity at each floor. A practical procedure to locate the centers of rigidity and hence floor eccentricity is introduced. This procedure depends on the use of plane frame computer programs only and is suitable for use in design offices. The seismic torsional provisions in the National Building Code of Canada 1985 (NBCC 1985) explicitly emphasize that the code provisions apply to buildings where the centres of rigidity lie on a vertical axis only. By means of examples, it verifies the claim of NBCC 1985. Also, it shows that, for buildings with centers of rigidity scattered from a vertical axis, the code procedure may or may not apply. Therefore, one should interpret the condition of centers of rigidity located along a vertical axis to be a sufficient, but not a necessary, condition for the NBCC 85 code provisions to be applicable. Until the necessary conditions are known, dynamic analysis remains the most reliable method to assign the torsional effects to various portions of the building. Key words: building code, center of rigidity, dynamic analysis, eccentricity, irregular, multistory, seismic, torsion.


Author(s):  
K. Chaidas ◽  
G. Tataris ◽  
N. Soulakellis

Abstract. In recent years 3D building modelling techniques are commonly used in various domains such as navigation, urban planning and disaster management, mostly confined to visualization purposes. The 3D building models are produced at various Levels of Detail (LOD) in the CityGML standard, that not only visualize complex urban environment but also allows queries and analysis. The aim of this paper is to present the methodology and the results of the comparison among two scenarios of LOD2 building models, which have been generated by the derivate UAS data acquired from two flight campaigns in different altitudes. The study was applied in Vrisa traditional settlement, Lesvos island, Greece, which was affected by a devastating earthquake of Mw = 6.3 on 12th June 2017. Specifically, the two scenarios were created by the results that were derived from two different flight campaigns which were: i) on 12th January 2020 with a flying altitude of 100 m and ii) on 4th February 2020 with a flying altitude of 40 m, both with a nadir camera position. The LOD2 buildings were generated in a part of Vrisa settlement consisted of 80 buildings using the footprints of the buildings, Digital Surface Models (DSMs), a Digital Elevation Model (DEM) and orthophoto maps of the area. Afterwards, a comparison was implemented between the LOD2 buildings of the two different scenarios, with their volumes and their heights. Subsequently, the heights of the LOD2 buildings were compared with the heights of the respective terrestrial laser scanner (TLS) models. Additionally, the roofs of the LOD2 buildings were evaluated through visual inspections. The results showed that the 65 of 80 LOD2 buildings were generated accurately in terms of their heights and roof types for the first scenario and 64 for the second respectively. Finally, the comparison of the results proved that the generation of post-earthquake LOD2 buildings can be achieved with the appropriate UAS data acquired at a flying altitude of 100 m and they are not affected significantly by a lower one altitude.


2020 ◽  
Vol 25 ◽  
pp. 469-481
Author(s):  
Kay Rogage ◽  
David Greenwood

The operation and maintenance of built assets is crucial for optimising their whole life cost and efficiency. Historically, however, there has been a general failure in the transfer information between the design-and-construct (D&C) and operate-and-maintain (O&M) phases of the asset lifecycle. The recent steady uptake of digital technologies, such as Building Information Modelling (BIM) in the D&C phase has been accompanied by an expectation that this would enable better transfer of information to those responsible for O&M. Progress has been slow, with practitioners being unsure as to how to incorporate BIM into their working practices. Three types of challenge are identified, related to communication, experience and technology. In examining the last aspect, it appears that a major problem has been that of interoperability between building information models and the many computer-aided facilities management (CAFM) systems in use. The successful and automatic transfer of information from a building model to an FM tool is, in theory, achievable through the medium of the Industry Foundation Classes (IFC) schema. However, this relies upon the authoring of the model in terms of how well its structure permits the identification of relevant objects, their relationships and attributes. The testing of over 100 anonymised building models revealed that very few did; prohibiting their straightforward mapping to the maintenance database we had selected for the test. An alternative, hybrid approach was developed using an open-source software toolkit to identify objects by their geometry as well as their classification, thus enabling their automatic transfer. In some cases, manual transfer proved necessary. The implications are that while these problems can be overcome on a case-by-case basis, interoperability between D&C and O&M systems will not become standard until it is accommodated by appropriate and informed authoring of building models.


Author(s):  
Z. Li ◽  
W. Zhang ◽  
J. Shan

Abstract. Building models are conventionally reconstructed by building roof points via planar segmentation and then using a topology graph to group the planes together. Roof edges and vertices are then mathematically represented by intersecting segmented planes. Technically, such solution is based on sequential local fitting, i.e., the entire data of one building are not simultaneously participating in determining the building model. As a consequence, the solution is lack of topological integrity and geometric rigor. Fundamentally different from this traditional approach, we propose a holistic parametric reconstruction method which means taking into consideration the entire point clouds of one building simultaneously. In our work, building models are reconstructed from predefined parametric (roof) primitives. We first use a well-designed deep neural network to segment and identify primitives in the given building point clouds. A holistic optimization strategy is then introduced to simultaneously determine the parameters of a segmented primitive. In the last step, the optimal parameters are used to generate a watertight building model in CityGML format. The airborne LiDAR dataset RoofN3D with predefined roof types is used for our test. It is shown that PointNet++ applied to the entire dataset can achieve an accuracy of 83% for primitive classification. For a subset of 910 buildings in RoofN3D, the holistic approach is then used to determine the parameters of primitives and reconstruct the buildings. The achieved overall quality of reconstruction is 0.08 meters for point-surface-distance or 0.7 times RMSE of the input LiDAR points. This study demonstrates the efficiency and capability of the proposed approach and its potential to handle large scale urban point clouds.


Author(s):  
Yehorova O.I. ◽  
Kozlova Yu.V.

The article aims at analyzing the topical English pandemic (coronavirus) vocabulary from the perspective of system-functional approach. This envisages performing following tasks: 1) to identify the pandemic (coronavirus) lexical cluster, 2) to describe the word-building peculiarities of the English coronavirus vocabulary and 3) to interpret the functioning of this vocabulary within the political, every day, and Internet discourses.Methods. The methodological framework used in the study features: 1) generalization for establishing basic theoretical principles of the research; 2) structure-semantic analysis for studying the word-building specifics of the pandemic vocabulary; 3) statistical method for defining calculate the frequency and the productivity of certain word-building models within the pandemic lexical cluster; 4) the elements of discourse analysis to highlight the functional peculiarities of coronavirus vocabulary.Results. Coronacrisis, that we have experienced till the present, has become a crucial factor catalyzing nomination processes of the novel concepts, thus influencing the lexical system of the English language. We consider pandemic lexicon (coronavirus vocabulary) the novelist group of neologisms in the English language since it comprises innovative words and phrases which have been coined since the start of COVID-19 pandemic and relate to its impact on the modern life. Among the most common for coronavirus vocabulary word-building models are derivation, compounding, shortening, loan and substitution; alongside, the statistical analysis has proved blending to be the most productive word-building model. The study of functional peculiarities of the pandemic lexicon within various types of discourses shows that its biggest part has entered the usus. The use of pandemic vocabulary within the Internet discourse is marked by the development of a number of thematic groups of language units referring to: 1) routine activities and events; 2) changes in learn and work modes; 3) excess weight; 4) alcohol and 5) verbal aggressiveness.Conclusions. The study enabled categorizing the units of the English pandemic (coronavirus) vocabulary as a separate lexical cluster, which has predominantly developed with the help of the already existing language resources. The units of this innovative cluster perform nominative function by naming new concepts and realia of life, reflect social moods, for instance, the feelings of worry, fear, anguish, and hopelessness, or facilitate the humorous effect in communication. Prospects for future research lie within the expansion of discursive analysis of pandemic innovations for revealing functional of some neological units on different stages of the COVID-19 pandemic, as well as conducting a comparative study of pandemic innovations in distant languages.Key words: word-building, lexical innovation, pandemic vocabulary, discourse. Метою пропонованого дослідження є висвітлення актуального пандемійного (коронавірусного) вокабуляру англійської мови з позицій системно-функціонального підходу. Досягненню мети сприяє виконання таких завдань: 1) ідентифікувати пандемійний (коронавірусний) лексичний кластер; 2) охарактеризувати словотвірні особливості коронавокабуляра англійської мови та 3) проінтерпретувати особливості функціонування коронавокабуляра в політичному, повсякденному та інтернет-дискурсах.Методи. Для досягнення поставленої мети застосовувалися: 1) метод узагальнення для ідентифікації базових теоретич-них положень; 2) метод структурно-семантичного аналізу для вивчення особливостей словотвору пандемійного вокабуляра; 3) статистичний метод для вирахування частотності та продуктивності словотворення пандемійного лексичного кластера за конкретними моделями; 4) елементи дискурс-аналізу для вивчення функціональних особливостей короновокабуляра.Результати. Коронакриза, що триває нині, є центральним фактором впливу на лексикографічну систему англійської мови, оскільки актуалізувала проблему номінації нових реалій. Найактуальнішою неологічною групою англійської мови нині є пандемійна лексика (коронавірусний вокабуляр), до складу якого, зокрема, входять інноваційні слова та вирази, що виникли з початку пандемії COVID-19 та пов’язані з її впливом на сучасне життя. Елементи коронавокабуляра утворюються за низкою дериваційних моделей, до числа яких відносимо деривацію, основоскладання, скорочення, запозичення, субституцію, проте найпродуктивнішою моделлю за результатами статистичного аналізу є телескопія. Дослідження особливостей функціонуван-ня коронавірусного вокабуляра в різних типах дискурсу дає змогу констатувати превалювання узуальної лексики та тісні між-дискурсивні зв’язки, зокрема між політичним дискурсом та дискурсом повсякденності. Використання пандемійної лексики на просторах інтернет-дискурсу відзначається формуванням низки лексико-семантичних груп на позначення: 1) рутинних занять та подій; 2) змін у звичному розпорядку навчальної та робочої діяльності; 3) зайвої ваги; 4) алкоголю та 5) мовної агресії.Висновки. Проведене дослідження уможливило виокремлення англомовного пандемійного (коронавірусного) вокабуляра як окремого лексичного кластера, основу якого становить загальновживана лексика. Одиниці цього інноваційного кластера виконують номінативну функцію через іменування нових реалій та концептів життя, а також рефлектують настрої суспільства, зокрема відчуття занепокоєння, остраху, туги та безнадійності, або ж сприяють реалізації гумористичного ефекту комунікації.Ключові слова: словотворення, лексична інновація, пандемійний вокабуляр, дискурс.


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