检索结果-内蒙古大学图书馆

作者： Meixedo, A. Alves, V. Ribeiro, D. Calçada, R. Faculty of Engineering University of Porto Portugal Post-Graduate Program in Civil Engineering Federal University of Ouro Preto Brazil School of Engineering Polytechnic of Porto Portugal

This paper aims selects sensitive features for damage identification in a railway bridge. For this purpose, a damage identification methodology based on a genetic algorithm and its application to the numerical model of a railway bridge is proposed. The identification method is based on an iterative process that in each iteration compares the values of the dynamic responses of a bridge for a test damage scenario with the response values for a reference damage scenario. The introduction of damage in the test numerical model is based on the modification of preselected numerical parameters values. The genetic algorithm allows the identification of damage by minimizing the residue of an objective function constructed from the responses of the test and reference model, and based on damage indicators. In this study damage indicators, based on the deck accelerations of the bridge subject to the action of the Alfa Pendular train defined as a set of moving loads, are defined and tested. The proposed methodology for identifying damage has been tested using a two-dimensional numerical finite element model of a railway bridge including the railway track. The results enabled the evaluation of the efficiency and reliability of the methodology and of the damage indicators which, in most situations, showed potential for the detection, location and quantification of the severity of the damage. © civil-Comp Press, 2016.

关键词： Genetic algorithms

来源：评论

学校读者我要写书评

暂无评论

Influence of chord stresses on the strength of RHS joints 9

Influence of chord stresses on the strength of RHS joints

引用

9th International Conference on Advances in Steel Structures, ICASS 2018

作者： Mendes, Flávio F. de Lima, Luciano R.O. da Vellasco, Pedro C. G. S. Rodrigues, Monique C. Neves, Luis F.C. PGECIV - Civil Engineering Post-Graduate Program UERJ - State University of Rio de Janeiro Brazil Structural Engineering Department UERJ - State University of Rio de Janeiro Brazil INESCC Civil Engineering Department University of Coimbra Portugal

ISBN: (纸本)9889914093

Extensive work has been performed to address the technological and design issues of tubular joints in the last decades. Several international design codes and recommendations explicitly cover the design of tubular joints such as Eurocode 3, ISO14346 and NBR16239. Experimental results on the influence of the chord stresses over the brace load capacity have been published in the literature. These results showed that compressive chord stresses considerably reduce the joint resistance. However, very few studies indicated the same reduction in load carrying capacity for joints under the action of chord tensile forces. To investigate this influence, an experimental program comprising thirteen tests was carried out, i.e. tests without chord axial forces;tests with compressive chord forces;and other ones with tensile chord forces. The obtained results were compared to the design provisions. This assessment indicated that the results obtained for chords without axial forces and with compressive forces, in experiments were safe when compared to the values predicted by all the investigated standards. On the other hand, the results associated with cases with chord tension forces proved to be conservative. Copyright © 2018 by The Hong Kong Institute of Steel Construction.

关键词： Software testing

来源：评论

学校读者我要写书评

暂无评论

Structural behaviour of T RHS joints subjected to chord axial force 15

Structural behaviour of T RHS joints subjected to chord axia...

引用

Proceedings of the 15th International Symposium on Tubular Structures, ISTS 2015

作者： Nizer, A. De Lima, L. Da S. Vellasco, P. De Andrade, S. Da S. Goulart, E. Da Silva, A.T. Da C. Neves, L.F. PGECIV – Civil Engineering Post-Graduate Program UERJ – State University of Rio de Janeiro Brazil Structural Engineering Department UERJ – State University of Rio de Janeiro Brazil INESCC Civil Engineering Department University of Coimbra Portugal

ISBN: (纸本)9781138028371

This paper presents an experimental and numerical analysis of the chord normal stresses influence on the "T" tubular joints behaviour. The experimental program consisted of six tests: two without chord axial forces;two with compressive chord forces;and the remaining two with tensile chord forces. These results were compared to numerical results obtained with the aid of the ANSYS 12.0 software, and to the design provisions present in the: Eurocode 3;NBR 16239:2013 Brazilian standard and ISO 14346. This assessment indicated that the results obtained for chords without axial forces and with compressive forces, in both experiments and numerical analyses, were safe when compared to the values predicted by all the investigated standards, where the best fit was obtained by ISO 14346. On the other hand, the results associated to cases with chord tension forces proved to be conservative. © 2015 Taylor & Francis Group, London.

关键词： Software testing

来源：评论

学校读者我要写书评

暂无评论

Determination of time zero in high strength concrete containing superabsorbent polymer and nano-silica

引用

Journal of Building Pathology and Rehabilitation 2016年第1期1卷 1-12页

作者： Cunha, T.A. Francinete, P. Manzano, M.A. Aidar, L.A. Borges, J.G. Silva, E.F. Post-Graduate Program in Structures and Civil Construction (PECC/UnB) University of Brasília Brasília Federal District Brazil Civil Engineering Department (ENC/UnB) University of Brasília Brasília Federal District Brazil

The autogenous shrinkage is a phenomenon that occurs due to the appearance of tensile stresses in capillary pores. Inherent in the hydration process, not depending on external interference. In high strength concrete, autogenous shrinkage is most pronounced, due to the refinement of microstructure, the high cement content, presence of mineral addictions and low water/cement ratio, which interfere in the transport of water curing. In this context, Superabsorbent polymers (SAP) stand out for their ability to reduce or eliminate the autogenous shrinkage, because they absorb large amounts of water, which is subsequently released into the matrix, avoiding self-desiccation and the onset of tensile stresses (internal curing). However, studies show that SAP can reduce the mechanical strength, which can be compensated by addiction of Nano-silica (NS). In this paper, the effect of these additions in Time Zero (T₀) was evaluated. T₀ determines the time at which the material starts to behave as a solid, with the development of a rigid mineral skeleton to oppose the volumetric variations that occurs in the paste, which can lead to cracking, compromising esthetics, durability, and structures safety. The ultrasonic pulse velocity test performed the T₀, which measures the velocity of propagation of an ultrasonic wave through the material and is taken as the time when a sudden change occurs at this velocity. Nine blends were made containing SAP and NS, where it was found that SAP addition increases the T₀ (up to 11%), while NS decrease its value (in 55%). © 2016, Springer International Publishing Switzerland.

关键词： High performance concrete High strength concrete Nano-silica Superabsorbent polymer Time zero Ultrasonic pulse velocity

来源：评论

学校读者我要写书评

暂无评论

Fiber reinforced polymers for historical bridges upgrading: a fatigue life assessment

引用

Journal of Building Pathology and Rehabilitation 2023年第1期8卷 1-11页

作者： Garcez, Mônica Regina Meneghetti, Leila Cristina Post-Graduate Program in Civil Engineering: Construction and Infrastructure Federal University of Rio Grande do Sul Porto Alegre Brazil Department of Structural and Geotechnical Engineering University of São Paulo São Paulo Brazil

Upgrading historical structures is one of the most interesting applications of fiber reinforced polymers in construction. Historical bridges are frequently post-strengthened to increase load carrying capacity of structural elements, aiming to bear heavier commercial traffic. Fatigue life becomes crucial since the lack of available fatigue models leads to superficial analysis considering the same S–N curves for different strengthening systems and steel stress ranges. This paper uses an extensive database with experimental data from the literature to adjust linear regression models to characterize the large scatter between the results of fatigue tests from different sources. Distinct fatigue models have been developed considering three categories: externally bonded reinforcement with strips/sheets and new surface-mounted reinforcement. The different declivities found for the adjusted fatigue life models accurately represent the fatigue behavior of the post-strengthened structural elements with the assessed systems and techniques. The results support design decisions to avoid future unnecessary interventions. © 2023, The Author(s), under exclusive licence to Springer Nature Switzerland AG.

关键词： Fatigue life Fiber reinforced polymers Historical bridges Linear regression analysis

来源：评论

学校读者我要写书评

暂无评论

Identification of spatial potential flood-prone area using topographic wetness index under the digital elevation model of Kr. Keureuto watershed, North Aceh. 5

Identification of spatial potential flood-prone area using t...

引用

5th Aceh International Symposium on civil engineering 2024, AISCE 2024

作者： Rizalihadi, Maimun Meilianda, Ella Yulianur, Alfiansyah Away, Yuwaldi Doctoral Program Post Graduate Program Syiah Kuala University Banda Aceh Indonesia Civil Engineering Department Syiah Kuala University Banda Aceh Indonesia Electro and Computer Engineering Department Syiah Kuala University Banda Aceh Indonesia

Floods are the most frequent disaster events in Lhoksukon, resulting in significant losses and community and environmental damage. Floods are generated by several factors, consisting of hydrometeorological, topographical, geological, soil, and human activities. Topography is a key controlling factor in flood initiation. Topographic analysis for detecting flood susceptibility, especially flood inundation, can be conducted using the TWI. The research aims to identify the potential spatial distribution of flood-prone areas based on TWI and assess the model accuracy using the ROC-AUC method. A case study was conducted in the Kr. Keureuto watershed. of North Aceh. TWI analysis is based on the topography of an area denoted by extracting DEM using GIS to create slope, flow direction, and flow accumulation. Higher TWI values are associated with higher flood susceptibility. The results show that the value of TWI is approximately 1.571-27.147, showing that more than 20% of area are potentially flood inundations with high and very hight rating of flood susceptibility. Furthermore, based on the analysis using field observation flood is obtained the AUC value of 71,60%. It can be concluded that the spatial model of flood-prone using TWI is good and effective for determining flood prone region in the Kr. Keureuto River basin © 2024 Institute of Physics Publishing. All rights reserved.

关键词： Watersheds

来源：评论

学校读者我要写书评

暂无评论

A neural network modelling of steel joint block shear capacity

A neural network modelling of steel joint block shear capaci...

引用

9th International Conference on the Application of Artificial Intelligence to civil, Structural and Environmental engineering, AIcivil-Comp 2007

作者： Rodrigues, F. Neto, L. Biondi Da S. Vellasco, P.C.G. De Lima, L.R.O. Vellasco, M.M.B.R. Post-Graduate Program in Civil Engineering Brazil Electronic Engineering Department Brazil Structural Engineering Department State University Rio de Janeiro Brazil Electrical Engineering Department Pontifical Catholic University Rio de Janeiro Brazil

ISBN: (纸本)9781905088201

Despite the multiple failure modes associated to bolted steel joints the block shear failure is frequently the controlling limit state of gusset plates, tension members and coped beam joints. The block shear rupture is characterised by a condition where a steel block area, nearby the holes of bolted joint region, reaches its maximum capacity dictated by a tension to shear interaction. If the joint is loaded beyond this limit a steel block is eventually separated from the main structure. Many models have been proposed to avoid shear block failure in steel design. These models incorporate a combination of the various hypotheses that control the structural rupture. In the majority of cases, it involves a combination of rupture and yielding in the tension and shear planes of the designed joint. Various design formula for this structural engineering problem were proposed all over the years but a closed solution has not yet been reached, due to the influence of several independent parameters. Many studies have already been carried out with the available experimental data, however, non negligible errors are still present in the current design formulae. The main objective of the present paper is to present a back propagation neural network evaluation of the block shear phenomenon. The main neural network input parameters were the geometrical and material variables that control the block shear design. The neural network output parameter was the block shear capacity. The neural network training was based on experimental results present in literature and adopted cross validation techniques to avoid the neural network overfitting. The neural network results were promising, with reduced associated errors and confirmed the possibility of using this methodology to generate trustworthy data. These new data, coupled with the existent experiments, can help the production of more accurate design formulae. © civil-Comp Press, 2007.

关键词： Neural networks

来源：评论

学校读者我要写书评

暂无评论

Acoustic performance of closing panels used in steel-structured buildings

Acoustic performance of closing panels used in steel-structu...

引用

18th International Congress on Sound and Vibration 2011, ICSV 2011

作者： Ribas, Rovadávia A.J. Souza, Henor A. Civil Engineering Post-Graduate Program Universidade Federal de Ouro Preto Escola de Minas Campus Morro do Cruzeiro 35400-000 Ouro Preto - MG Brazil

ISBN: (纸本)9781618392596

In this research, it was made the evaluation of the acoustic performance of some closing systems mostly used in steel-structured buildings in Brazil, for instance walls made of the cement plates, precast concrete panels and plasterboard walls. The acoustic performance was evaluated by estimating the sound transmission loss that occurs through them using a simplified graphical method. It was studied the performance of these kinds of panels and their combinations forming double panels, with and without sound-absorbing material between them. Copyright © (2011) by the International Institute of Acoustics & Vibration.

关键词： Precast concrete

来源：评论

学校读者我要写书评

暂无评论

Finite element modelling of steel beams with web openings

Finite element modelling of steel beams with web openings

引用

11th International Conference on civil, Structural and Environmental engineering Computing, civil-Comp 2007

作者： Rodrigues, F. Da Vellasco, P.C.G.S. De Lima, L.R.O. De Andrade, S.A.L. Da Silva, J.G.S. Post-Graduate Program in Civil Engineering State University of Rio de Janeiro Brazil Structural Engineering Department State University of Rio de Janeiro Brazil Mechanical Engineering Department State University of Rio de Janeiro Brazil

ISBN: (纸本)9781905088157

Height limitations are frequent in multi-storey buildings due to zoning regulations, economic requirements and esthetical considerations. On the other hand, substantial spaces are normally required to enable the passage of large pipes and ducts beneath steel beams leading to uneconomic floor heights. The most adopted solution is the use of holes at the steel beam webs in order to enable the passage of services. Chung et al. [1], [3] state that nowadays services that require web openings up to 75% of the beam height are not uncommon. These openings could lead to a significant decrease of the beam load carrying capacity depending on the adopted holes shape, size and location. This motivated the present study that used finite elements simulations to quantitative and qualitative evaluates the structural behaviour of steel beams with web openings. This paper presents the developed finite element models using the ANSYS [6] program to investigate the structural response of steel beams with web openings. The analysis incorporated geometric and material non-linearities and were calibrated against numerical and test results to validate the proposed finite element models. The investigation also contemplated the simulations of beams with a series of holes distributed all over their length known as cellular beams. The imulations were centred at the evaluation of the different steel beams with web penings failure mechanisms and the main reasons for yours collapse modes. © 2007 civil-Comp Press.

关键词： Finite element method

来源：评论

学校读者我要写书评

暂无评论

Experimental evaluation of composite tubular columns CFDST (Stainless steel-concrete-carbon steel) 9

Experimental evaluation of composite tubular columns CFDST (...

引用

9th International Conference on Advances in Steel Structures, ICASS 2018

作者： Rodrigues, Pedro F. da Vellasco, Pedro C. G. S. de Lima, Luciano R.O. da Silva, André T. Rodrigues, Monique C. Sarmanho, Arlene M.C. Civil Engineering Post-Graduate Program State University of Rio de Janeiro UERJ Rio de Janeiro Brazil Structural Engineering Department State University of Rio de Janeiro UERJ Brazil Civil Engineering Department Federal University of Ouro Preto UFOP Brazil

ISBN: (纸本)9889914093

This paper is centred on the structural response of double skin composite columns made of two concentric tubes of stainless and carbon steels filled with concrete. These structural solutions can be used in new structures or even in cases where a reinforcement or retrofit is required to enhance their corrosion resistances or structural capacities. An experimental programme was conducted to investigate this innovative structural system by means of comparisons to standard concrete encased tubular steel stub columns. The experimental results widened their applications to cases where a high reserve of post-collapse resistance is required like in seismic design. An assessment of the Eurocode 4 predictions for these tubular columns indicated the design prediction formulae are too conservative, partly explained by the lack of consistent numerical and experimental results that could enable a better design calibration. Copyright © 2018 by The Hong Kong Institute of Steel Construction.

关键词： Tubular steel structures

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：