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A Asadi, A Hadavi, R J. Krizek

Bridge Life-Cycle Cost Analysis Using Artificial Neural Networks

Abstract: Life-Cycle Cost analysis can significantly assist in making investment decisions. Several recentstudies have recognized the potential benefits of Life-Cycle Cost analysis and call for use of suchanalyses when making infrastructure investments, including investments in bridges. The Life-CycleCost of a bridge consists of the total investment throughout the life of the bridge. This includes theinitial construction cost, repair and rehabilitation costs, and all maintenance costs. The ability toaccurately determine the Life-Cycle Cost of a bridge will help agencies evaluate the asset value ofexisting bridges, make better decisions on the design and construction of new ones, and chooseimproved methods and approaches for rehabilitating existing structures. Research has shown thattimely maintenance, repair, and rehabilitation can lower the Life-Cycle Cost of a bridge. However, thisis a complex and nonlinear problem, and previous studies have failed to develop a satisfactory model. One effective technique for solving nonlinear problems with complicated functions is an ArtificialNeural Network. A neural network is a powerful data-modeling tool that captures and representscomplex input/output relationships. Using a set of input and output data belonging to a particularproblem, a neural system can be trained to predict outcomes for new versions of the same problem.Accordingly, an extensive set of data (bridge dimensions, age, initial cost, and Life-Cycle Cost) for 14Chicago bridges was used to quantify the degree of success that could be achieved with this model.Sixty percent of the data was used as input to train the model and the remaining forty percent was usedto assess the success of the model for predicting the Life-Cycle Cost. The results achieved wereencouraging and suggest that the neural network model is a promising tool for predicting the LifeCycleCost ofa bridge.

Keywords: life-cycle cost, artificial neural network, Chicago Trunnion Bascule bridges. initial cost, repair and rehabilitation cost

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Series: w78:2011 (browse)
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Elenas A

Computer supported evaluation of interrelations between seismic acceleration parameters and the behaviour of structures

Abstract: This paper describes first some acceleration parameters of seismic excitations. Next, a nonlinear analysis of a reinforced concrete plane frame is carried out to elaborate the influence of the aforementioned parameters on the behaviour of the structure. Damage indicators in the form of cross sectional ductility demand are then evaluated and correlated with the strong motion characteristics. Furthermore, the ductility demand is compared with the cross sectional ductility supply of the structure. The aim of this computer supported study is t o extract among the several here presented seismic parameters, those which have drastic affection on the damage indicators of the structures.

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Series: ecce:1997 (browse)
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Ge Ji and O. Burkan Isgor

On The Numerical Solution Of Laplace's Equation With Nonlinear Boundary Conditions For Corrosion Of Steel In Concrete

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Series: w78:2006 (browse)
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Kilar V, Krstulovič-Opara N

Seismic behavior of high-performance fiber reinforced composite frames

Abstract: The paper explores the possibilities to use a High-Performance Fiber Reinforced Concretes (HPFRCs) for design of seismic resistant cost-effective and durable buildings. Composite frame buildings are made through selective use of different HPFRCs: Slurry Infiltrated Mat Concrete (SIMCON), Slurry Infiltrated Fiber Concrete (SIFCON) and High Strength - Lightweight Aggregate Fiber Reinforced Concrete (HS-LWA FRC) which further minimizes dead and seismic loads. The first part of the paper briefly describes used HPFRCs and proposed composite building system consisted of composite columns, beams and specially designed fuses that connect the two. In the second part of the paper the results of the nonlinear static analysis of an isolated composite beam as well as of the nonlinear dynamic analysis of a whole four-story example composite building are presented. The response in terms of forcedisplacement relationships and rotational ductility factors as well as in terms of base shear, top displacements and global damage index histories is compared to the response of an identical classical four-story building made of reinforced concrete.

Keywords: fiber reinforced concrete, high performance fiber reinforced concrete, composite building structures, seismic behavior, frame structures, nonlinear analysis

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Series: itaec:2003 (browse)
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Kilar V

Computer program for linear and nonlinear analysis of tall buildings subjected to horizontal loading

Abstract: In Slovenia, as in many other countries where earthquake or wind loading can be excessive, the stiffness of a tall building is governed by horizontal loading. The paper presents a computer program for linear (static and dynamic) and for nonlinear push-over analysis of symmetric and asymmetric building structures subjected to horizontal loads (such as wind or earthquake loads). The paper briefly describes the used mathematical model and the analysis method for nonlinear static analysis. As an example, the program is used for the nonlinear pushover analysis of several (symmetric and asymmetric) variants of four-storey reinforced- concrete building structure consisted of frames and walls. The results, that are presented in a form of normalized charts, give a valuable information about the nonlinear behavior of different structure variants.

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Series: ecce:1997 (browse)
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M Zhou, J-G Nie, J-S Fan

Nonlinear Full-Process Shear Analysis of RC Structural Members Using Planar Membrane Element: Implementation and Application

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Full text: content.pdf (273,462 bytes) (available to registered users only)

Series: w78:2014 (browse)
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Mao Zhi, Goh Bee Hua, Wang Shouqing, Ofori G

Forecasting construction industry-level total factor productivity growth using neural network modeling

Abstract: Total Factor Productivity (TFP) is widely recognised as a better indicator than Labour Productivity and Multi-Factor Productivity to represent industry-level productivity performance. Productivity is the key determinant of a nation's standard of living and an industry's competitiveness. As such, the ability to predict trends in TFP growth in the construction industry is very important. The factors influencing TFP growth in the construction industry are complicatedly interrelated. This fact made the conventional regression method highly inadaptable to such complex multi-attribute nonlinear mappings. As an AI information-processing tool, the artificial neural network (ANN) system has been proven to be a powerful approach to solving complex nonlinear mappings with higher accuracy than regression methods. However, so far, there has been little application of ANNs in predicting TFP growth in the construction field. This study will for the first time, apply the concepts of ANNs to develop a model to forecast the TFP growth in the case of the construction industry of Singapore. Macro-level information processing models are useful in monitoring and predicting the performance of the construction industry as a whole. With the need to manage construction performance information at all three levels, namely, industry, firm and site, this study looks specifically at developing an 'intelligent' model for forecasting industry-level productivity. Meanwhile, using the same set of data, a model developed by the Multiple Linear Regression method will serve as a benchmark to judge the performance of the ANN model. The ANN model, compared with the traditional regression model, would be expected to have better forecasting ability for TFP growth in the construction industry, in terms of accuracy.

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Full text: content.pdf (79,002 bytes) (available to registered users only)

Series: w78:2002 (browse)
Cluster: papers of the same cluster (result of machine made clusters)
Class: class.analysis (0.037562) class.processing (0.012219) class.legal (0.002318)
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Permission to reproduce these documents have been graciously provided by the Aarhus School of Architecture, Denmark. The assistnace of the editor, Prof. Kristian Agger, is gratefully aprecciated.


Moller B, Hoffmann A, Kluger J

Assessment of critical load situations during the life cycle of concrete structures

Abstract: In dimensioning reinforced concrete structures in accordance with EC2, an alternative method of describing the system load-bearing behaviour is by nonlinear simulations over significant periods of the life cycle. The realistic reinforced concrete FE model presented here takes into account nonlinear material laws for concrete and steel, fracture behaviour and composite action as well as viscous behaviour (nonlinear creep and shrinkage). Considering the example of a reinforced concrete box-type folded plate structure, critical loading situations (especially high shear loads) were investigated which lead to system failure at different times in the life cycle of the structure. System load-bearing reserves are clearly indicated by resultant stress redistributions.

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Rafal Kicinger, Artur Winnicki, Tomasz Arciszewski, Kenneth De Jong

Evolutionary design for blast of steel structural systems

Abstract: This paper introduces a novel concept of evolutionary design for blast of steel structural systems. It pro-vides both conceptual and computational frameworks for conducting automated concept generation, analysis, dimen-sioning, and optimization. The proposed concept has been developed through the integration of various results from previous research on evolutionary design, structural analysis using the finite element method, and computer simula-tions of blast utilizing computational fluid dynamics. The paper describes the architecture and individual components of the computer system implementing the proposed concept. The system has been built upon the evolutionary design platform developed at George Mason University. In the developed system, blast loads have been determined using FEFLO, an advanced computational fluid dynamics sys-tem created in the Center for Computational Fluid Dynamics at GMU. Structural design and optimization is conducted by Emergent Designer, an integrated research and design support tool developed by the first author. The analysis is performed by ABAQUS, an advanced system for finite element analysis, which allows the explicit structural analysis and evaluation of dynamic behavior of steel structural systems under blast loads when nonlinear behavior of materials and structure is considered. The developed system enables automatic generation of parameterized designs both at the conceptual and detailed de-sign levels. This was achieved through fully parameterized and object-oriented interfaces connecting major components of the system. This full parameterization facilitates automatic parameterized 3D finite element model generation from the level of dimensions of sketches defining cross-sections of structural members to the level of 3D assemblies of solid parts representing entire structural systems.

Keywords: structural design, blast effects, evolutionary computation, finite element analysis, engineering software

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Series: w78:2007 (browse)
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Yazdani S, Schreyer H L

Nonlinear response of plain concrete shear walls with damage

Abstract: During earthquakes, the natural frequencies of concrete structures are often significantly lower than those predicted by conventional linear elasticity. This can cause severe motion of piping systems because the design of support structures utilizes values of predicted natural frequencies. In an experimental program to investigate the problem, a further decrease in stiffness was noted for model concrete structures. In this study continuum damage mechanics is proposed as a constitutive model for describing both the changes in natural frequencies, and the reduction in initial stiffness of small concrete structures. Structural members made with brittle materials such as concrete experience damage under seismic excitation, which is reflected through altered natural frequencies for the structure. With regard to scale models, it is suggested that micro cracking as a result of shrinkage may be the source of the loss in initial stiffness. Shrinkage cracks are easily reflected in the constitutive equation as initial isotropic damage. Finite element predictions based on anisotropic damage mechanics indicate that the proposed approach may be practicable for routine engineering analyses.

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Full text: content.pdf (339,877 bytes) (available to registered users only)

Series: itaec:2003 (browse)
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