• Title/Summary/Keyword: codes-of-practice

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Automatic decomposition of unstructured meshes employing genetic algorithms for parallel FEM computations

  • Rama Mohan Rao, A.;Appa Rao, T.V.S.R.;Dattaguru, B.
    • Structural Engineering and Mechanics
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    • v.14 no.6
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    • pp.625-647
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    • 2002
  • Parallel execution of computational mechanics codes requires efficient mesh-partitioning techniques. These mesh-partitioning techniques divide the mesh into specified number of submeshes of approximately the same size and at the same time, minimise the interface nodes of the submeshes. This paper describes a new mesh partitioning technique, employing Genetic Algorithms. The proposed algorithm operates on the deduced graph (dual or nodal graph) of the given finite element mesh rather than directly on the mesh itself. The algorithm works by first constructing a coarse graph approximation using an automatic graph coarsening method. The coarse graph is partitioned and the results are interpolated onto the original graph to initialise an optimisation of the graph partition problem. In practice, hierarchy of (usually more than two) graphs are used to obtain the final graph partition. The proposed partitioning algorithm is applied to graphs derived from unstructured finite element meshes describing practical engineering problems and also several example graphs related to finite element meshes given in the literature. The test results indicate that the proposed GA based graph partitioning algorithm generates high quality partitions and are superior to spectral and multilevel graph partitioning algorithms.

A nonlinear model for ultimate analysis and design of reinforced concrete structures

  • Morfidis, Konstantinos;Kiousis, Panos D.;Xenidis, Hariton
    • Computers and Concrete
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    • v.14 no.6
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    • pp.695-710
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    • 2014
  • This paper presents a theoretical and computational approach to solve inelastic structures subjected to overloads. Current practice in structural design is based on elastic analysis followed by limit strength design. Whereas this approach typically results in safe strength design, it does not always guarantee satisfactory performance at the service level because the internal stiffness distribution of the structure changes from the service to the ultimate strength state. A significant variation of relative stiffnesses between the two states may result in unwanted cracking at the service level with expensive repairs, while, under certain circumstances, early failure may occur due to unexpected internal moment reversals. To address these concerns, a new inelastic model is presented here that is based on the nonlinear material response and the interaction relation between axial forces and bending moments of a beam-column element. The model is simple, reasonably accurate, and computationally efficient. It is easy to implement in standard structural analysis codes, and avoids the complexities of expensive alternative analyses based on 2D and 3D finite-element computations using solid elements.

The Consequences of Data Fabrication and Falsification among Researchers

  • KANG, Eungoo;HWANG, Hee-Joong
    • Journal of Research and Publication Ethics
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    • v.1 no.2
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    • pp.7-10
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    • 2020
  • Purpose: The experience by a researcher highlighted steps is guided by a specific ethical codes of conduct. The purpose of the current study is to discuss the fabrication and falsification of data as the key ethical misconduct committed by many researchers focus on their causes and impact in the research field. Research design, data and methodology: To obtain suitable textual resource, the current study used content analysis to closely take a look at the fabrication and falsification based on prior research in the realm of publication ethics. As a result, the current authors could collect and understand adequate textual data from appropriate prior resources. Results: The Research misconduct is a common practice in different countries across the world. Based on the findings from this study, data fabrication or falsification have a grievous impact on all the stakeholders of a study. The unethical behavior affects the parties concerned both psychologically and financially. Conclusions: It is, therefore, recommended that researchers should be held accountable. This can be done through different means, including raising awareness of vulnerability to data fabrication and falsification. The government and research institute should also advocate for effective policies guiding research studies across the world.

Study on Settlement Calculation of the Long-Short Pile Composite Foundation

  • XU, Xin;Kwag, Yunehyeong;Chun, Byungsik
    • Journal of the Korean GEO-environmental Society
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    • v.14 no.7
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    • pp.13-18
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    • 2013
  • As a new foundation treatment technology, long-short pile composite's design theory is still in primary phase, and there are no explicit settlement calculation methods in active codes. So it is necessary to study the working mechanism and the methods of settlement calculation. In this paper, the mechanics of long-short pile composite foundation are fully discussed. Meanwhile, based on the shear deformation method, the Mylonakis & Gazetas models about mutual action between two piles and the one between pile and soil are introduced, Considering the performance of cushion, the flexible factors of mutual actions are provided. Then the settlement calculation of long-short pile composite foundation which can consider the mutual actions between pile, soil and cap is deduced, and the correlated program is also developed. Finally, an engineering example is discussed with the method. A comparison shows that calculated results and measured data from a field test pile are in a good agreement, indicating that the presented approach is feasible and applicable in engineering practice.

Structural performance of unprotected concrete-filled steel hollow sections in fire: A review and meta-analysis of available test data

  • Rush, David;Bisby, Luke;Jowsey, Allan;Melandinos, Athan;Lane, Barbara
    • Steel and Composite Structures
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    • v.12 no.4
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    • pp.325-350
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    • 2012
  • Concrete filled steel hollow structural sections (CFSs) are an efficient, sustainable, and attractive option for both ambient temperature and fire resistance design of columns in multi-storey buildings and are becoming increasingly common in modern construction practice around the world. Whilst the design of these sections at ambient temperatures is reasonably well understood, and models to predict the strength and failure modes of these elements at ambient temperatures correlate well with observations from tests, this appears not to be true in the case of fire resistant design. This paper reviews available data from furnace tests on CFS columns and assesses the statistical confidence in available fire resistance design models/approaches used in North America and Europe. This is done using a meta-analysis comparing the available experimental data from large-scale standard fire tests performed around the world against fire resistance predictions from design codes. It is shown that available design approaches carry a very large uncertainty of prediction, suggesting that they fail to properly account for fundamental aspects of the underlying thermal response and/or structural mechanics during fire. Current North American fire resistance design approaches for CFS columns are shown to be considerably less conservative, on average, than those used in Europe.

The structural performance of axially loaded CFST columns under various loading conditions

  • Huang, Fuyun;Yu, Xinmeng;Chen, Baochun
    • Steel and Composite Structures
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    • v.13 no.5
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    • pp.451-471
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    • 2012
  • Concrete filled steel tube (CFST) structures have been used widely in high-rise buildings and bridges due to the efficiency of structurally favourable interaction between the steel tube and the concrete core. In the current design codes only one loading condition in the column members is considered, i.e., the load is applied on the steel tube and concrete core at the same time. However, in engineering practice the tube structures may be subjected to various loading conditions such as loading on the concrete core only, preloading on the steel tube skeleton before filling of concrete core, and so on. In this research, a series of comparative experiments were carried out to study the structural performance of concrete filled circular steel tube columns subject to four concentric loading schemes. Then, a generalized prediction method is developed to evaluate the ultimate load capacity of CFST columns subject to various loading conditions. It is shown that the predictions by the proposed method agree well with test results.

Probabilistic Analysis of Lifetime Extreme Live toads of Multi-Story Columns (고층기둥 축하중의 사용기간 최대값 분석)

  • 김상효;조형근;배규웅;박홍석
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1990.10a
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    • pp.69-72
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    • 1990
  • The live loads acting on structures are generally computed in terms of equivalent uniformly distributed loads for the simplicity in design process. The loads, therefore, tend to decrease with increasing influence area in both load intensity and variance. Since multi-story column loads result from accumulation of loadings acting on several different floors, its influence area becomes wider and lifetime maximum decreases. In the design codes proposing the design loads for types of structural members (i.e., slabs, beams, columns), not for tile change of influence area, some proper reduction factors are given for columns which support more than one floor. Using the live load models developed for colons supporting single floor, in this study, the probabilistic characteristics of multi-story column loads are analyzed. In addition reduction factors given for multi-story columns in current practice are calibrated.

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Probabilistic Analysis of Lifetime Extreme Live Loads of Multi-Story Columns (고층기둥 축하중의 사용기간 최대값에 대한 확률론적 분석)

  • 김상효;박흥석
    • Computational Structural Engineering
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    • v.5 no.3
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    • pp.113-118
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    • 1992
  • The live loads acting on structures are generally computed in terms of equivalent uniformly distributed loads for the simplicity in design process. The loads, therefore, tend to decrease with increasing influence area in both load intensity and variance. Since multi-story column loads result from accumulation of loadings action on several different floors, its influence area becomes wider and lifetime maximum decreases. In the design codes proposing the design loads according to types of structural members(i.e., slabs, beams, columns), rather than the change of influence area, some proper reduction factors are given for columns which support more than one floor. Using the live load models developed for columns supporting single floor, in this study, the probabilistic characteristics of multi-story column loads are analyzed. In addition reduction factors given for multistory columns in current practice are calibrated.

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Experimental study on the spray density distribution of water spray system in road tunnel (터널 물분무소화설비의 살수밀도분포에 대한 실험연구)

  • So, Soo-Hyun;Park, Kyung-Hwan
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.13 no.1
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    • pp.1-8
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    • 2011
  • Spray density of the water spray system which is installed in long road tunnels and hazardous vehicle tunnels is applied without proper performance assessment process. In this study, the requirements of Spray Density Guidelines at the standard pressure is investigated through spray test set up the nozzle of a water spray system in a simulated road tunnel. The results showed that all the nozzles used in the test area did not meet the requirements of the Guidelines. The absence of performance test codes and inspection process on the nozzle at real scale in tunnels may have caused this practice. Therefore, it is suggested that the performance test regulations of the nozzle on the water spray system is established in order to properly assess the system performance.

A Comparative Study on the Evaluation of Bearing Capacity for Driven Pile in Static Load Test (현장정재하시험 결과를 통한 타입말뚝 지지력 판정법 비교 연구)

  • Chun, Byung-Sik;Seo, Deok-Dong;Choi, Heon-Kil;Yoon, Hwan-Ho
    • Proceedings of the Korean Geotechical Society Conference
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    • 2005.03a
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    • pp.677-686
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    • 2005
  • The allowable bearing capacity of a pile, the most important factor in stability estimation, is determined by applying safety factor to the ultimate load or yield load. There are several but contradictory methods available in current design codes to estimate the allowable bearing capacity and the safety factor. This paper analyzes load-settlement curves obtained from 19 static load tests measured from 11 sites. At all tests, the load is applied until apparent failure is observed. The validity of the ultimate and yield load estimation method and load caculated from the settlement criterion is investigated through comparison with the measured data. In addition, a new procedure to estimate allowable load and safety factor is proposed. Additional data from field static load tests, such as those incorporated in this study, are needed to more reliably apply the proposed method in design practice.

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