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Load Distribution Assessment of reinforced concrete buildings During Construction with Structural Characteristic Parameter Approach

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Tsinghua Science and Technology 2009年第6期14卷 746-755页

作者：方东平席海峰王晓明张传敏赵挺生 School of Civil Engineering Tsinghua University Urban Systems Program CSIRO Sustainable EcosystemsCommonwealth Scientific and Industrial Research Organisation(CSIRO) Henan Development and Reform Commission School of Civil Engineering and Mechanics Huazhong University of Science and Technology

High-rise reinforced concrete buildings are in great demand in developing countries with rapid urbanization. Construction engineers are facing more and more safety control challenges. One major issue is the understanding of the load distributions, especially the maximum slab load, of structures under construction, which is time dependent. Previous methods were mainly targeted to specific examples, providing specific solutions without addressing the fundamental issues of finding general solutions for load distributions in reinforced concrete buildings with different geometrical and material characteristics during construction. The concept of a structural characteristic parameter is used here to parametedze the main geometrical and material characteristics of concrete structures for generalized assessments of load distributions during construction. The maximum slab load for 20 different construction shoring/reshoring schemes is presented. The results indicate that the traditional simplified method may underestimate or overestimate the maximum slab load, depending mainly on the shoring/reshoring schemes. The structural characteristic parameter approach was specifically developed to assist construction engineers to estimate load distributions to assure safe construction procedures.

关键词： reinforced concrete buildings construction load re-distdbution structural characteristic parameter: slab-shore interaction

Influences of Shrinkage,Creep,and Temperature on the Load Distributions in reinforced concrete buildings During Construction

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Tsinghua Science and Technology 2009年第6期14卷 756-764页

作者：方东平席海峰王晓明张传敏 School of Civil Engineering Tsinghua University Urban Systems Program CSIRO Sustainable EcosystemsCommonwealth Scientific and Industrial Research Organisation(CSIRO) Henan Development and Reform Commission

Site measurements have shown that slab loads re-distribute, between the slabs during the concrete curing, while the external Ioadings and structural geometry remain the same. Some have assumed that this is caused by concrete shrinkage and creep, but there have been no studies on how these factors exactly influence the load distributions and to what degree these influences exist. This paper analyzes the influences of concrete shrinkage, creep, and temperature on the load re-distributions among slabs. Although these factors may all lead to load re-distribution, the results show that the influence of concrete shrinkage can be neglected. Simulations indicate that shrinkage only reduces slab loads by a maximum of 1.1%. Creep, however, may reduce the maximum slab load by from 3% to 16% for common construction schemes. More importantly, temperature variations between day and night can cause load fluctuation as large as 31.6%. This analysis can, therefore, assist site engineers to more accurately estimate slab loads for construction planning.

关键词： reinforced concrete buildings construction load re-distribution structural characteristic parameter slab-shore interaction shrinkage creep and temperature

Investigation on a mitigation scheme to resist the progressive collapse of reinforced concrete buildings

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Frontiers of Structural and Civil Engineering 2012年第4期6卷 421-430页

作者： Iman TABAEYE IZADI Abdolrasoul RANJBARAN Department of Civil Engineering Faculty of EngineeringUniversity of ShirazShirazIran

This study presents the investigation of the approach which was presented by Thaer *** Alrudaini to provide the alternate load path to redistribute residual loads and preventing from the potential progressive collapse of RC *** was proposed to transfer the residual loads upwards above the failed column of RC buildings by vertical cables hanged at the top to a hat steel braced frame seated on top of the building which in turn redistributes the residual loads to the adjacent *** this study a ten-storey regular structural building has been considered to investigate progressive collapse *** design is based on ACI 318-08 concrete building code for special RC frames and the nonlinear dynamic analysis is carried out using SAP2000 software,following UFC4-023-03 *** independent failure scenarios are adopted in the investigation,including six external removal cases in different floors and three removal cases in the first floor.A new detail is proposed by using barrel and wedge to improve residual forces transfer to the cables after removal of the *** results show that progressive collapse of building that resulted from potential failure of columns located in floors can be efficiently resisted by using this method.

关键词： prevent progressive collapse alternate load path reinforced concrete buildings nonlinear dynamic retrofitting cable steel hat braced frame barrel and wedge

Influence of earthquake direction on the seismic response of irregular plan RC frame buildings

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Earthquake Engineering and Engineering Vibration 2014年第2期13卷 243-256页

作者： Magliulo G Maddaloni G Petrone C University of Naples Federico II Department of Structures for Engineering and Architecture University of Naples Parthenope Department of Engineering

The nonlinear response of structures is usually evaluated by considering two accelerograms acting simultaneously along the orthogonal directions. In this study, the infl uence of the earthquake direction on the seismic response of building structures is examined. Three multi-story RC buildings, representing a very common structural typology in Italy, are used as case studies for the evaluation. They are, respectively, a rectangular plan shape, an L plan shape and a rectangular plan shape with courtyard buildings. Nonlinear static and dynamic analyses are performed by considering different seismic levels, characterized by peak ground acceleration on stiff soil equal to 0.35 g, 0.25 g and 0.15 g. Nonlinear dynamic analyses are carried out by considering twelve different earthquake directions, and rotating the direction of both the orthogonal components by 30° for each analysis(from 0° to 330°). The survey is carried out on the L plan shape structure. The results show that the angle of the seismic input motion signifi cantly infl uences the response of RC structures; the critical seismic angle, i.e., the incidence angle that produces the maximum demand, provides an increase of up to 37% in terms of both roof displacements and plastic hinge rotations.

关键词： plan irregularity nonlinear analyses reinforced concrete buildings seismic performance ground motion directionality

Deformation Analysis Due to Early Loading of concrete buildings

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Journal of Civil Engineering and Architecture 2016年第6期10卷 690-695页

作者： Romildo Alves Berenguer Fernando Artur Nogueira Silva Joao Luiz de Melo Ramos Fabio Cameiro Lourenco Pryscylla Femanda Silva Chaves Ana Cecilia Ferreira Leite Department of Civil Engineering Catholic University of Pernambuco Recife 51110-200 Brazil

The building industry has experienced in recent years a strong growth in demand in general and in the case of reinforced concrete buildings this increase has been more marked. This fact has also contributed to accelerate all stages of the production process of these constructions with more pronounced effects on the methodologies used in the constructive steps that influence directly the structural design of the building. Structures loaded at ever earlier ages, in which the strength and deformation properties of materials are not yet sufficiently mature. It is a variable that needs to be taken into account already in the design phase so that the concrete structure behaves within acceptable level of reliability taking into account design code recommendations for service life. To understand the importance of constructive effects and to assess its magnitude in the execution of reinforced concrete buildings, this paper presents result from nonlinear analyses using finite element method adopting an approach commonly referred as staged construction applied to a typical building found in the practice. The effects of creep and shrinkage were considered and the results obtained demonstrate that the strains due to constructive effects can, in certain cases, assume representative values which, if ignored, can lead to important pathologies in the building.

关键词： reinforced concrete buildings constructive effects staged construction creep shrinkage.