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Turbo generator pedestals are one of the critical structures in any power plant complex. Stringent vibration requirements particularly at the bearing locations have been stipulated for proper functioning of turbo generator installations. Normally the dynamic analysis is carried out using a deterministic approach with constant material properties. The effect of variability of modulus of elasticity of concrete, and operating speed of the turbo generator can lead to increased amplitudes of vibration. The designer always looks for conservative estimates of the expected responses and is interested in keeping them within allowable limits. This paper provides a methodology for computing peak dynamic response at bearing locations once the results of the dynamic analysis with a given input stiffness is available. The approach is essentially based on modal synthesis of responses, namely contribution of individual modes to amplitude of vibration at a particular location. The frequency range of interest is divided into three regions, namely, nonresonant region where undertuned conditions exist, nonresonant region where overtuned conditions exist, and the resonant region. Simple analytical formulation has been developed to compute the peak dynamic response and is illustrated with an example. The suggested method can be programmed for effective use through spread sheet and MS EXCEL software. [ABSTRACT FROM AUTHOR]

Tracking vehicles through roundabouts is laborious. Because of this, turning movement volumes are usually estimated using a variety of methods. This paper identifies and evaluates practical methods of estimating turning movement volumes at roundabouts. Thirty four experiments were used to test the effects of different estimation treatments: estimation procedure, time interval size, count location configuration, and turning movement sample procedure. A new economical sampling procedure was introduced and included in the experiment design. The experiments were evaluated using volume estimation and capacity estimation errors. Findings showed that the new sample procedure works well relative to a random sampling procedure. Other insights were gained regarding the four treatments included in the experiment design. [ABSTRACT FROM AUTHOR]

Provides information on the finalists and winner of the 'Journal of Professional Issues in Engineering Education and Practice' Best Paper Award for the period October 2000-July 2001.

We compare four methods for progressive collapse analysis by analyzing a nine-story steel moment-resistant frame building, employing increasingly complex analytical procedures: linear-elastic static, nonlinear static, linear-elastic dynamic, and nonlinear dynamic methodologies. Each procedure is thoroughly investigated and common shortcomings are identified, along with advantages and disadvantages, using side-by-side comparison, including approximate time spent on modeling and computation. The evaluation uses current General Services Administration progressive collapse guidelines. Our objective is to provide clear conceptual step-by-step descriptions of various procedures for progressive collapse analysis by performing example analyses using commercially available structural analysis software, such as SAP2000, with the aim that the explanations in this paper will be clear enough that they will be readily understandable and will be used by practicing engineers. We demonstrate that dynamic analysis procedures not only yield more accurate results, but are also easy to perform for progressive collapse determination. Additionally, we show that current GSA performance limits for linear analysis procedures are unconservative, meaning that a structure designed with acceptable linear evaluation criteria may exceed allowable ductility and rotation limits when nonlinear dynamic analysis is performed on the same structure. Finally, our recommendations for the analysis procedures take into account accuracy as well as ease of use. [ABSTRACT FROM AUTHOR]

This paper introduces a technique that directly predicts the failure patterns of laterally loaded masonry panels based on the results of existing typical panels tested in the laboratory. The technique is based on the use of the cellular automata (CA). In this technique, the CA modeling is established to propagate boundary effects to zones within a panel. The corresponding rules for the state values of zones are derived from the proposed CA model, using appropriate transition functions. These state values are then used by the CA to establish zone similarity between two panels. Finally, the zone similarity is applied to establish locations of cracks on the panel. The technique is used in a novel way that eliminates the use of any numerical tools such as finite-element analysis (FEA). This technique is purely based on comparing the failure pattern of the base panel (a panel whose failure pattern is known from the laboratory tests) and unseen panels (panels not tested in the laboratory by the writers or with unknown failure patterns) subjected to the same type of loading and with similar boundary conditions to predict the failure load of the unseen panels. [ABSTRACT FROM AUTHOR]

Genetic algorithms allow solution of more complex, nonlinear civil, and environmental engineering problems than traditional gradient-based approaches, but they are more computationally intensive. One way to improve algorithm performance is through inclusion of local search, creating a hybrid genetic algorithm (HGA). The inclusion of local search helps to speed up the solution process and to make the solution technique more robust. This paper focuses on the effects of different local search algorithms on the performance of two different HGAs developed in previous phases of this research, the self-adaptive hybrid genetic algorithm (SAHGA) and the enhanced SAHGA. The algorithms are tested on eight test functions from the genetic and evolutionary computation literature and a groundwater remediation design case study. The results show that the selection of the local search algorithm to be combined with the simple genetic algorithm is critical to algorithm performance. The best local search algorithm varies for different problems, but can be selected prior to solving the problem by examining the reduction in fitness standard deviation associated with each local search algorithm, and the time distribution associated to the local search algorithm. [ABSTRACT FROM AUTHOR]

This paper deals with an application of neural networks for computation of fundamental natural periods of buildings with load-bearing walls. The analysis is based on long-term tests performed on actual structures. The identification problem is formulated as the relation between structural and soil basement parameters, and the fundamental period of building. The principal component analysis for compression of input data is also used. Backpropagation neural networks are applied in the analysis. Results of neural network identification of natural periods are compared with data from experiments. The application of the proposed neural networks enables us to identify the natural periods of the buildings with quite satisfactory accuracy for engineering practice. The compression of the input data to principal components by principal component analysis makes it possible to design much smaller neural networks than those without data compression with no greater increase of the neural approximation errors. It appears that this technique would also be very useful in damage detection and health monitoring of structures. [ABSTRACT FROM AUTHOR]

The Saint Venant equations are often combined into a single equation for ease of solution. As a result however, this single equation gives rise to several redundant nonlinear terms that may impose significant limitations on model analyses. In order to avoid this, our paper employs a new procedure that separates, in the Laplace frequency domain, the governing equation of water depth from that of flow velocity and thus enables us to consider two independent equations rather than two coupled ones. The so-obtained analytical solutions are valid for prismatic channels of any shape. Solution validity is assured by repeated comparison with the corresponding numerical solutions based on Crump’s algorithm, which accelerates solution convergence. Utilizing this new procedure, this paper will construct a basic wave spectrum for classifying subcritical flow waves in a prismatic channel. The spectrum is basically a contour plot of the normalized specific energy loss for a small water wave moving in the channel for a finite distance of approximately 100 m. The distance is chosen so that four distinct regions with different contour patterns that represent kinematic, diffusion, gravity, and dynamic waves in a river are shown in the spectrum. By incorporating the spectrum with Ferrick’s criteria and Manning’s formula, a single contour line is also generated, which serves as the boundary of the four regions. Example computations show that the spectrum predicts a similar trend of wave attenuation for waves propagating in a trapezoidal channel. When the rising speed of a wave is of concern, the full Saint Venant equations are solved numerically to reconstruct a similar spectrum good for supercritical flow as well. [ABSTRACT FROM AUTHOR]

The existing Det Norske Veritas (DNV) Recommended Practice RP E305 for pipeline on-bottom stability is mainly based on the pipe–soil interaction model reported by Wagner et al. in 1987, and the wake model reported by Lambrakos et al. in 1987, to calculate the soil resistance and the hydrodynamic forces upon pipeline, respectively. Unlike the methods in the DNV Practice, in this paper, an improved analysis method is proposed for the on-bottom stability of a submarine pipeline, which is based on the relationships between Um/(gD)0.5 and Ws/(γD2) for various restraint conditions obtained by the hydrodynamic loading experiments, taking into account the coupling effects between wave, pipeline, and sandy seabed. The analysis procedure is illustrated with a detailed flow chart. A comparison is made between the submerged weights of pipeline predicted with the DNV Practice and those with the new method. The proposed analysis method may provide a helpful tool for the engineering practice of pipeline on-bottom stability design. [ABSTRACT FROM AUTHOR]

The Internet has revolutionized the way computing is done and the way software systems work. Many systems, such as search engines and PC games, have utilized Web-related technologies for Web-based systems. However, the application of Web-based engineering software is still in its infancy, especially regarding engineering computing. This paper presents a prototype development of Web-based structural engineering systems by utilizing modern computer graphics and information technology to provide Web-based analytical services. The system design emphasizes platform-independence, graphical interface, system performance, and a multiple-user environment. The user needs only an Internet-connected machine to access high-performance services provided at remote sites over the Web. This framework will provide users a powerful tool to efficiently perform analysis with minimal computer resource requirements. The user will always have access to the most up-to-date and functional system with no client-side updates or maintenance required. Two Web-based system implementations are given as examples in this paper. [ABSTRACT FROM AUTHOR]

Ductile end cross frames have been proposed in the past for seismic design of steel plate girder bridges. In this paper buckling-restrained braces (BRBs) are investigated as ductile end cross frames and compared against the performance of yielding X braces. Component experiments on the BRBs showed that these braces dissipated energy very efficiently and have stable hysteretic behavior. Shake-table experiments on a large scale bridge model investigated the performance of braces with both pin-ended connections and fixed-end connections. Despite slippage, the pin-ended connections are considered more effective as flexural action in the relatively short braces is prevented. The base shear in the bridge model in response to 2.0 times the El Centro earthquake was 69% of the elastic base shear at an average drift of 2.5% during experiments. The relatively large deformation capacity of the BRBs, although not as great as the X braces, is necessary to achieve a significant reduction in base shear. The maximum cross frame displacements with the BRBs are consistently smaller than those in X braces at the same level of base shear. [ABSTRACT FROM AUTHOR]

For assessing the integrity of damaged hollow section joints, the plastic collapse loads of the joints containing cracks is an important parameter. Very little published information is available in the literature concerning the residual strength of square hollow section (SHS) joints containing defects or cracks. In this paper, an accurate numerical modeling of SHS T joints with cracks is proposed, whereby the entire finite element mesh is generated automatically. To validate this numerical model, several T joint models are studied and compared with the experimental data. A good agreement is obtained on the ultimate loads. Based on this model, the plastic collapse loads under different geometrical ratios are studied, and they are compared with the results calculated from the yield line theory. It is found that the yield line theory can give a reasonable prediction of the plastic collapse loads when the brace width to chord width ratio β is less than 0.8. The failure assessment diagrams (FAD), constructed using the J-integral predictions, have confirmed that the standard BS7910 Level 2A FAD is appropriate for determining limits of safe loading of cracked SHS T joints, provided the plastic collapse load is calculated using the yield line formulae neglecting the influence of the welds. [ABSTRACT FROM AUTHOR]

This paper is concerned with the application of the direct strength method to equal angle section beam-columns with locally unstable legs. In contrast to existing design methods, which independently determine the compression and bending capacities and use an interaction equation to combine these, the direct strength method determines the elastic local buckling stress for the actual stress distribution resulting from the combined action of compression and bending, and incorporates the elastic buckling stress into a direct strength equation for beam-columns. In applying the method to equal leg angles, the torsional buckling mode is ignored when determining the overall buckling capacities, since it is accounted for through the local buckling mode, and the shift of the effective centroid is incorporated as an additional loading eccentricity. The shift in the effective centroid resulting from local buckling is determined from the actual stress distribution, as obtained using Stowell’s classical solution, in place of an effective cross section. The predicted strengths are conservative compared to tests on slender equal angle columns, and are shown to accurately predict the variation in load with applied loading eccentricity. [ABSTRACT FROM AUTHOR]

A theory presented previously by the writer explained the asymmetric flow patterns occurring in symmetric rectangular expansions with subcritical flow. The theory is extended in the present paper to supercritical flows, in which the hydraulic jump is one of the flow features. The theory is shown to agree with available observations. Transverse oscillatory conditions are discussed in terms of a dynamic instability that can accompany static stability. The ranges for which experimental data are available with which to test the theory are identified, making it apparent where additional data would be useful for the full range of the problem. The phenomenological understanding provided by the present paper is important to the development of stabilization measures. In addition to stabilization by submergence, the hydraulic jump should be amenable to stabilization by other referenced methods, including various vane configurations and pipe communication between the eddy regions. [ABSTRACT FROM AUTHOR]

One of the possible uses of the global positioning satellite permanent stations is to use them as a datum reference when a new base station is established in a geodetic or surveying project. However, the actual procedure is not always obvious. Combining a number of permanent stations in the process involves important decisions that the analyst must make, which can alternate the results dramatically. Important network design aspects that must be addressed are, for example, how many permanent stations should be involved in the process; how long should the session duration be; how should one constrain the permanent stations in the adjustment procedure; and so forth. This paper suggests an algorithm based on multibaseline processing, minimum constraints, and free net adjustment concepts, in order to produce a base station with reliable coordinates and realistic accuracy, while using one or more permanent stations. In order to demonstrate the algorithm and to support the conclusions, it presents numerical examples from the Permanent Stations Array in the State of Israel, processed at the Technion—Israel Institute of Technology, using GAMIT software. [ABSTRACT FROM AUTHOR]

This paper presents a research methodology combining the contingent value method (CVM) and the Delphi model, creating an interactive stakeholder interaction to enhance decision making and influence project performance and funding of civil engineering (CE) projects. While CE has historically focused only on physical infrastructure needs, the CVM–Delphi model allows for maximum stakeholder participation in determining asset value. Specifically, the research model discussed in this paper gathered information from three groups (decision makers, businesses, and the general public) through three rounds of survey instruments gaging asset valuation of a recent highway renovation in rural Illinois. The methodology provides a viable tool for decision makers in other engineering arenas to increase customer focus prior to enacting policies or projects. [ABSTRACT FROM AUTHOR]

Performance-based engineering concepts applied to both structural design and assessment have gained interest among structural engineers and researchers in recent years. Performance-based design applied to building systems includes selection of appropriate structural systems and configurations to ensure that the structure has adequate strength, stiffness, and energy dissipation capacity to respond to loadings, including those arising from natural hazards, without exceeding permissible damage states. Although performance-based design has advanced for some materials and structural types, such as steel and reinforced concrete buildings and bridges built in high seismic regions, the application to light-frame wood structures has only recently been explored. This paper investigates the application of fragility techniques to the seismic design of engineered woodframe shearwalls. The methodology developed herein provides a technical basis for the development of future performance-based design provisions for shearwalls in light-frame structures subject to earthquake loading. In the present study, shearwalls are treated as isolated subassemblies. Nonlinear dynamic time-history analysis is used to predict the performance of the shearwalls considering a suite of suitably scaled characteristic ordinary ground motions taken to represent the seismic hazard. Examples of fragility curves are developed considering peak wall displacement and ultimate uplift force at the hold-down. The effects of nailing schedule, seismic weight, and choice of response modification factor (R) are considered. [ABSTRACT FROM AUTHOR]

Energy sector capital projects typically cost hundreds of millions and even billions of dollars. Managing the engineered equipment is important not only because of their high dollar value but also because the long manufacturing lead times often drive the overall project schedules. In recent years, several supplier alliances have been successfully implemented on such projects leading to initial price savings in the range from 6 to 10%. This paper presents the result of a study to assess the opportunities and barriers with such partnerships. Interviewed company executives perceived that time savings and quality improvements, mostly due to the suppliers’ specialized expertise, are of much greater value than a lower bid price. Most surprisingly, very few companies use metrics to measure performance, thus leaving them in the dark on the question of how well an alliance worked or why it failed. The relevance of the presented work is in the amount of actual field data that has been generated and processed. [ABSTRACT FROM AUTHOR]

By observing that the optimal basis for the proper orthogonal decomposition (POD) can be obtained from the cross power spectral density (XPSD) matrix of a multivariate stationary Gaussian stochastic process, the computational efficiency, in both time and memory consumption, of simulations of this process is improved by using a hybrid spectral representation and POD approach with negligible loss of accuracy. This hybrid approach actually simulates another multivariate process with many fewer variables in an optimal subspace obtained by the POD. This approach is straightforward, effective, and does not place any conditions on the XPSD matrices. Furthermore, the error induced by the reduction of variables is predictable and controllable prior to the simulation procedure. The spectral representation method (SRM) is discussed in a heuristic way. In this paper, a specific POD theorem is formally stated, proved, and related to XPSD matrices. A numerical example is given to demonstrate the effectiveness of this hybrid approach. This approach may also have potential applications for simulations of nonstationary non-Gaussian processes. [ABSTRACT FROM AUTHOR]

Assessing the structural response and vulnerability of bridge piers to collisions by barges typically involves either the use of static pier analysis codes and design-specification-stipulated equivalent static loading conditions, or a lengthy model development process followed by use of general-purpose finite-element codes. In this paper, an alternative approach is proposed that leverages the capabilities of existing nonlinear dynamic pier analysis programs by adding dynamic barge behavior in a computationally efficient and modular manner. By coupling nonlinear barge and pier responses together through a shared collision impact force and employing numerical procedures for accelerating convergence of the coupled system, dynamic barge collision analyses may be conducted for bridge piers efficiently and rapidly. The influence of impact parameters such as barge type and mass, impact speed and angle, and pier configuration can then be efficiently evaluated using dynamic collision analyses. For demonstration purposes, the method is implemented in an existing pier analysis program, validated, and used to conduct selected case studies. [ABSTRACT FROM AUTHOR]

System identification methodologies are useful for identifying characteristics of structural systems using measurement data. However, incorrect systems might be identified when many combinations of system characteristics result in the same predicted responses at measured locations. The reliability of identification is affected by a number of factors that most previous work has overlooked. This paper presents a system identification methodology that explicitly treats factors that affect the success of identification. Rather than simply determining parametric values, this methodology also involves identification of model characteristics including boundary conditions. Due to inevitable modeling errors, models that provide absolute minimum differences between predictions and measurements are rarely correct models. In such situations, the challenge is to define a population of candidate models that result in such differences being below threshold values that are determined by the magnitude of modeling errors. The methodology is illustrated using a case study in civil engineering. This work contributes to providing engineers with general strategies to meet interpretation challenges associated with sensor data. [ABSTRACT FROM AUTHOR]

During the last 3 decades interest has grown globally in the application of ductile steel plate walls (DSPWs) (or steel plate shear walls) for building lateral load resistance. The supporting theory has evolved from both analytical and experimental research conducted in several countries around the world. The advantages of using DSPWs as the lateral force resisting system in buildings include stable hysteretic characteristics, high plastic energy absorption capacity, and enhanced stiffness, strength and ductility. A significant number of experimental and analytical studies have been carried out to establish analysis and design methods for such lateral resisting systems. Despite these efforts there is still a need for a general analysis and design methodology that not only accounts for the interaction of the plates and the framing system but also can be used to better understand the linear and nonlinear behavior of different DSPW configurations. These configurations include DSPWs with thin or thick steel plates, and with or without stiffeners and openings. In this paper an analytical model of the DSPW that responds to this need and characterizes the structural behavior of these configurations is presented and discussed. The proposed model provides a good understanding of how the different components of the system interact, and is able to properly represent the system’s overall hysteretic characteristics, which can be readily incorporated in practical nonlinear analyses of buildings with DSPWs. The effectiveness of the method is demonstrated by comparing the predicted response with results from experimental studies performed by different researchers. [ABSTRACT FROM AUTHOR]

Establishing the strength requirements for stability bracing generally requires large displacement analyses on imperfect systems. In computational studies on stability bracing, choosing the critical shape of the imperfection can be a difficult decision, particularly for beam bracing systems. There are a number of factors that affect the stability brace forces including the shape and magnitude of the imperfection, the distribution of the imperfection along the length, and the value of the moment at the location of the brace. To develop suitable bracing design provisions, it is necessary to determine the maximum brace forces that are likely to occur in typical applications. However, determining the shape and distribution of the imperfection that produces the largest brace forces can be complicated. This paper studies the effect of different imperfection schemes on the magnitude of the stability brace forces. Results are presented that demonstrate the impact of several imperfection parameters on the bracing behavior and recommendations are made for selecting the critical imperfection shape that maximizes the stability brace forces for beam bracing systems. [ABSTRACT FROM AUTHOR]

This study evaluates the resource-constrained critical path method (RCPM), which the writers have recently proposed. RCPM establishes a critical path method (CPM)-like, resource-constrained schedule by resource-dependent activity relationships (or resource links) that the five-step RCPM technique identifies. With its CPM-like feature, RCPM provides the critical path and float data that are not available in traditional resource-constrained scheduling techniques. In addition, RCPM provides more flexibility to the schedule through identified alternative schedules, which allow certain activities to be executed beyond their late finish times without delaying the project completion. This paper evaluates the RCPM’s performance by comparing it with five related previous studies. A brief review of each study is also included in this paper. This comparison shows that RCPM performs well in identifying resource links and alternative schedules, compared to other methods. This study is of interest to academics because it highlights the advantages and disadvantages of different algorithms that have attempted to overcome present problems in traditional resource-constrained scheduling techniques. [ABSTRACT FROM AUTHOR]

Critical path method delay analysis techniques are widely applied in the construction industry, with the windows method being regarded as technologically advantageous. The approach looks at different schedule snapshots (windows) throughout the project and analyzes the contractor versus owner responsibility for delaying the critical paths. Accordingly, decisions regarding time and/or cost compensation could be made. While the technique is beneficial, it is computationally intensive and produces different results with different window sizes. Commercial software provide little support in this regard and the analysis is usually done manually. In this paper, a modified windows approach is introduced with computerized daily analysis of delays so that accurate and repeatable results are produced. The new approach is coupled with a new representation of progress information and is readily usable by professionals and researchers to evaluate project delays. Details of the daily analysis are introduced along with two case studies that demonstrate its advantages over the traditional windows approach. A downloadable version is made available for experimental use by researchers and professionals. [ABSTRACT FROM AUTHOR]

Engineering and design professionals constitute a major driving force for a successful project undertaking. Although the industry has been active in addressing the performance of construction labor and methods to estimate or predict such performance, relatively fewer efforts have been conducted for the engineering profession. In an attempt to fill out this gap, the paper presents a study to utilize neurofuzzy intelligent systems for predicting the engineering performance in a construction project. First, neurofuzzy systems are introduced as integrated schemes of artificial neural networks and fuzzy control systems. The use of these neurofuzzy intelligent systems, particularly fuzzy neural networks, in predicting engineering performance is then demonstrated in the industrial construction sector. The development of the system is based on actual project data that was collected through questionnaire surveys. Statistical variable reduction techniques are further employed to develop linear regression models of the same engineering performance prediction scheme, and results are being compared between both techniques. [ABSTRACT FROM AUTHOR]

With China’s fast economic growth and entry into the World Trade Organization (WTO), more foreign architectural, engineering, and construction (AEC) firms are expected to venture into this huge and attractive market. This paper explores the important strategies to help foreign AEC firms clinch construction projects in China. Using a questionnaire survey approach complemented by in-depth interviews, it was found that firms need to pay more attention to the market and working conditions in China and to strengthen their own capabilities. To win projects in China, foreign AEC firms should also be able to offer project financing services. The findings are useful to foreign AEC firms because it may help them win projects in the Chinese construction industry. [ABSTRACT FROM AUTHOR]

Technology has an incredible impact on the pricing and profitability of engineering services. Historically, pricing for engineering services has been based on labor-hours. However, some in the industry have experienced at least a tenfold increase in efficiency because of computer-aided design and the development of three-dimensional computer models. Consequently, the labor-hours spent on a project no longer adequately represent the value of the engineering services rendered. There is a need for engineers, designers, and consultants to revise old, and develop new, pricing strategies. The writers discuss current and foreseeable issues and constraints facing engineers today. On April 16, 2003, the ASCE San Francisco Younger Member Forum, (YMF) met to discuss the topic of pricing for engineering and consulting services. The presentation, discussion, and conclusions as well as a discussion of the current state of the marketplace and future technical developments in the industry are included in this paper. Pricing and contracting strategies are discussed and analyzed, and a call is made to industry, academics, and practitioners alike to address the pricing and perception problems outlined in this paper. [ABSTRACT FROM AUTHOR]

Reliability analysis of structural systems often requires finite element (FE)-based simulation to estimate failure probabilities. Common simulation methods, even those incorporating variation reduction techniques, usually involve a very large number of FE analyses to achieve acceptable accuracy. A recently developed directional approach significantly improves the efficiency of directional simulation by utilizing deterministic point sets to preserve the underlying joint probability distribution of the random vector describing the structure and by employing neural networks to focus the simulation effort in the significant regions. This paper investigates the application of this method to structural system reliability analysis. The method is illustrated using deformation-based system limit states, proposed for performance-based engineering, for two plane steel frames. [ABSTRACT FROM AUTHOR]

This paper addresses the question of what speed profile will minimize fuel consumption of a land transport vehicle (road or rail) in traversing a path or route. Numerous previous studies, using a control theory approach applied to specific profiles, have suggested that fuel consumption is approximately minimized by operation at constant speed. This result is derived much more directly here, along with boundaries on the conditions under which this result holds. The derivation relies on: (1) the approximate proportionality between fuel consumption and propulsive work; (2) the inherent resistance of a vehicle having the usual quadratic form (of road and rail vehicles); (3) the energy conversion characteristics of on-board gasoline or diesel (or diesel–electric) propulsion systems; and (4) relatively long distances between stops. Tests, using a train performance simulator, confirm the theoretical results. The results are discussed from the standpoint of basic principles in transportation engineering, and as guidance for designing systems that conserve fuel. [ABSTRACT FROM AUTHOR]

Highway megaprojects (construction projects over $100 million) are fraught with uncertainty. These projects have historically experienced increases in project costs from the time that a project is first proposed or programmed until the time that they are completed. Persistent cost underestimation reflects poorly on the industry in general but more specifically on engineers. Traditional methods take a deterministic, conservative approach to project cost estimating and then add a contingency factor that varies depending on the stage of project definition, experience, and other factors. This approach falls short, and no industry standard stochastic estimating practice is currently available. This paper presents a methodology developed by the Washington State Department of Transportation (WSDOT) for its Cost Estimating Validation Process. Nine case studies, with a mean cumulative value of over $22 billion, are presented and analyzed. Programmatic risks are summarized as economic, environmental, third party, right-of-way, program management, geotechnical, design process, construction, and other minor risks. WSDOT is successfully using the range cost output from this procedure to convey project costs to management and the public. [ABSTRACT FROM AUTHOR]

This paper presents the results of laboratory model tests on the influence of soil confinement on the behavior of a model footing resting on granular soil. Confining cylinders with different heights and diameters were used to confine the sand. The ultimate bearing load of a circular footing supported on a three-dimensional confined sand bed was studied. The studied parameters include the cell height, cell diameter, the depth to the top of the cell, and the embedded depth of footing. Initially, the response of a nonconfined case was determined and then compared with that of confined soil. The results were then analyzed to study the effect of each parameter. The results indicate that the bearing load capacity of circular footing can be appreciably increased by soil confinement. It was concluded that such reinforcement resists lateral displacement of soil underneath the footing leading to a significant improvement in the response of the footing. For small cell diameters, the cell–soil footing behaves as one unit (deep foundation), while this pattern of behavior was no longer observed with large cell diameters. The recommended cell heights, depths, and diameters that give the maximum bearing capacity improvement are presented and discussed. [ABSTRACT FROM AUTHOR]

The in situ deep mixing technique is an established means of enhancing bearing capacity and reducing settlement by placing columnar inclusions in soft ground. Developments in equipment and field techniques to implement this method have surpassed the basic understanding of strength development in soft clays admixed with cementing agents at water contents close to their liquid limit or higher. Laboratory tests on soft clays admixed with cementing agents are a prerequisite for engineering decisions on the proper mix proportions for intended field strength. This paper presents and analyzes test results on cement admixed soft clays within the basic framework of induced cementation of soft clays. It is possible to propose a clay–water/cement ratio formulation that enables calculation of cement contents consistent with changes in in situ water content. [ABSTRACT FROM AUTHOR]

This paper describes a research study that investigated methods for the integration of project documents in architecture, engineering, construction, and facility management (AEC/FM) model-based information systems and determined the formalisms and mechanisms needed to achieve this integration during the development and utilization of such systems. The main objectives were (1) to formalize methods to improve the organization and access of large document collections in project management information systems, and (2) to elaborate a methodology to integrate project documents in AEC/FM model-based information systems. [ABSTRACT FROM AUTHOR]

This paper contains an alternate method for the calculation of the predicted positive bending moment capacity of composite steel girders. The 2000 interim version of the American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design Bridge Design Specifications has extended the applicability of the provisions for the design of composite plate girders in positive bending to include 485 MPa high performance steel. Observations made during numerical studies performed in conjunction with this extension demonstrated a need for a more comprehensive study encompassing a larger and more diverse set of parameters. This paper provides a summary of the analytical and experimental work that was carried out to develop provisions for predicting the ultimate strength and assuring the ductility of composite girders constructed using 250, 345, or 485 MPa steels. The new provisions outlined in this paper are more accurate and require less calculation. The recommended equations only require calculation of the plastic moment capacity, while current AASHTO Specification provisions require the calculation of both plastic and yield moment capacities of the section. [ABSTRACT FROM AUTHOR]

The evaluation of consultant’s performance is crucial to the success of a consulting assignment especially when today’s construction projects are becoming more sophisticated, large-scale, and risky. However, since individual clients have developed their own consultant’s performance evaluation (CPE) procedures, the sharing of performance information, though desirable, may not be too meaningful as the results of evaluation could be inconsistent. There is a need to examine whether a unified framework can be derived for CPE. The aim of this paper is to improve the transparency and rigorousness of CPE through the establishment of an evaluating framework for gauging the performance of engineering consultants. In this paper, a comprehensive set of evaluation criteria is identified, and the significance of these criteria is discussed through an empirical survey. Then, a multicriteria model for evaluating the performance of engineering consultants is presented. The results indicate that once an acceptable CPE framework is devised, the performance scores can be utilized for various purposes, including monitor and control, incentive and sanction, preselection, technical assessment, and bid evaluation. [ABSTRACT FROM AUTHOR]

Pontesei Dam is a major concrete dam built after World War II across the canyon of Maè Creek (Valle di Zoldo) in the Italian Eastern Alps. Just upstream from the dam, a gully discharges water from steep mountains. The only road serving the dam and the entire valley upstream of the dam runs along the mountainside and crosses the gully. In 1959, an exceptionally rainy season caused a flood, which destroyed the bridge. A temporary Bailey bridge was subsequently built by the army, but in 1990 it was decided to design a new bridge. The main challenges posed to the designer included building the new deck and the abutments underneath the Bailey bridge without disrupting traffic, hoisting the deck just to the bottom of the Bailey bridge, and finally substituting the new deck for the Bailey bridge in one day. Other problems included the instability of the rock mass at the abutments and the gravitative convergence of the two sides of the gully. This paper describes the design, construction, and testing of the bridge replacement and the bridge abutments. [ABSTRACT FROM AUTHOR]

This paper presents a detailed investigation of warping-related stresses in 18 composite steel-concrete box girder bridges. The bridge designs were adapted from blueprints of existing bridges in the state of Florida and encompass a wide range of parameters including horizontal curvature, cross-sectional properties, and number of spans. The bridges after which the analysis prototypes are modeled were designed by different firms and constructed at different times and are considered to be representative of current design practice. Forces are evaluated from analyses that account for the construction sequence and the effect of warping. Loading is considered following the 1998 AASHTO-LRFD provisions. Differences between stresses obtained taking warping into account and those calculated by ignoring warping are used to evaluate the effect of warping. Analysis results show that warping has little effect on both shear and normal stresses in all bridges. Current design provisions are discussed in light of the analysis results. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the behavior of elastic–plastic specimens during testing in a triaxial apparatus. In particular, an investigation of the influence of a number of imperfections on the observed behavior of a specimen is performed. To this end, we present influences of end platen friction, end platen inclinations, and the shape of specimen on what we broadly understand by “constitutive behavior.” We investigate the issues related to the constitutive as opposed to boundary value behavior or elastic–plastic specimens. We present a number of examples to illustrate the differences between different types of response, which are usually, and wrongly, just called the constitutive behavior. [ABSTRACT FROM AUTHOR]

Performance of pavements has been affected by heave distress problems caused by sulfate rich soils treated with calcium-based stabilizers. A research study was conducted to address the effectiveness of sulfate resistant cement stabilizers Types I/II and V, for providing better treatment of sulfate rich soils. Experiments were designed and conducted on both control and cement treated sulfate soils to investigate compaction relationships, Atterberg limits, linear shrinkage and free swell strain potentials, unconfined compressive strength, and low strain shear moduli properties. This paper presents a comprehensive summary and analysis of these test results. Test results were statistically analyzed to study the potentials of sulfate resistant cement stabilization methods for significant enhancements to the strength and stiffness properties as well as reductions in swell and shrinkage strain potentials of natural sulfate rich soils. Mineralogical studies were used to verify research findings observed from the macro test results. [ABSTRACT FROM AUTHOR]

Reinforced soil is a practical solution to construction of unpaved roads or placement of footings over weak soils. A stability analysis of reinforced foundation soil is presented in this paper. A method is suggested for calculating limit loads on strip footings over foundation soils reinforced with horizontal layers of geosynthetics. Separate solutions are given for a case where reinforcement layers slip within the soil, and for a case where reinforcement ruptures. In the former case, an increase in the bearing capacity is dependent on the characteristics of the soil-reinforcement interface, whereas in the latter case it depends on the strength of the reinforcement. In both cases the increase in the limit load is dependent on the internal friction angle of the soil. Expressions are developed for quantitative predictions of bearing capacity of the foundation soil with horizontal layers of reinforcement. An optimum reinforcement depth is also given. [ABSTRACT FROM AUTHOR]

The paper describes an investigation carried out to examine the factors influencing collapse settlement of the compacted coal ash due to wetting. The ashes produced by the coal fired thermal power plants are stored as a high mound in the disposal dump. Some of the ash dumps and ash fill structures wetted under certain conditions of loading may exhibit collapse. Attempts have been made to correlate the ash characteristics and the specific placement parameters such as ash type, soluble content, degree of compaction, overconsolidation ratio, moisture content, and stress level at wetting with collapse. This was based largely on the oedometer and partly on the model and the field test results. 378 single oedometer tests were conducted to obtain the collapse potential. The collapse potential was correlated with the mean size of the ash. The favorable pressure, moisture, fines, compaction, soluble substance, and prestressing decrease the collapse potential of an ash fill. The collapsible and the noncollapsible ashes were identified by the results of oedometer test and laboratory model test. Normally, if the collapse potential in the oedometer is more than 0.01, the collapse of soils may occur in the field. However, the model test demonstrated this to be an unconservative criterion. A value of 0.0075 at 80% degree of compaction was found appropriate for the ashes examined. The paper explains the technique of field test performed at the controlled densities. The field test confirmed incidence of collapse on a rising water table for a collapsible ash. [ABSTRACT FROM AUTHOR]

This paper explores the use of mass/stiffness eccentricity in simple buildings to damp the response to excitation due to base motion. Examples include one- and two-story buildings when discussing low-rise structures and shear beams when discussing taller structures. Base motions include a simple step function and earthquake input. A broad range of efficiencies is achieved depending upon the system eccentricity and the available viscous damping. Asymptotic efficiencies of 50% are indicated in some cases. Optimal parameters are discussed. [ABSTRACT FROM AUTHOR]

Redecking operations executed on urban bridges that experience large traffic volumes frequently require carefully orchestrated construction sequences carried out during times of nonpeak traffic. In such a construction environment, only bridge deck options that exhibit a high degree of modularity in conjunction with ease of installation are considered as viable options for a given redecking operation. As a further requirement, the deck installation must also be expected to perform essentially trouble free, with minimal maintenance, for very long periods of time in extremely harsh environments. The present research investigates the behavior of two new deck splice details for use in bridge applications involving precast concrete-filled steel grid deck panels. The research is primarily experimental in nature and is carried out using full-scale deck panel specimens. However, in an effort to better understand the experimental results, 3D finite-element models of the deck specimens are also constructed and studied. This paper summarizes the results from this experimental and analytical program of study. [ABSTRACT FROM AUTHOR]

This paper treats the dynamic effect of traffic actions on the deck slabs of concrete road bridges using the finite-element method. All the important parameters that influence bridge-vehicle interaction are studied with a systematic approach. An advanced numerical model is described and the results of a parametric study are presented. The results suggest that vehicle speed is less important than vehicle mass and that road roughness is the most important parameter affecting the dynamic behavior of deck slabs. The type of bridge cross section was not found to have a significant influence on deck slab behavior. The dynamic amplification factor varied between 1.0 and 1.55 for the bridges and vehicles studied. These results should be validated by further work. [ABSTRACT FROM AUTHOR]

In this paper, derivation and computed formulas are provided for the shear lag coefficient in a simply supported prestressed concrete box girder under dead load. In the case of prestressed tendons having parabolic configurations, formulas to compute the shear lag effect are also developed. The magnitude of upward loading intensity caused by prestress as well as the relationship between the height of the box girder and the sag of prestressed tendons have been fully treated. Conclusions are drawn that the shear lag effect caused by dead load and prestress force is equivalent to dead load acting alone, provided that the prestressed tendon is set up with a parabolic profile. Shear lag effect caused by movable load is also analyzed according to the eccentricity of the load to the half-width ratio of the box girder. Charts were prepared to predict the shear lag coefficient for live load. Finally, having considered the shear deformation of flanges, the deflection of box girders is studied for both uniformly distributed load and concentrated load. Examples are given for illustrative purpose. [ABSTRACT FROM AUTHOR]

The preparation of detailed models of information and process flow by 14 member companies of the North American Precast Concrete Software Consortium has provided a unique window into the current management, engineering design, and production operations in this industry. The modeling was performed using the authors’ Georgia Tech Process for Product Modeling tool, within the framework of the consortium’s effort to develop a precast concrete product model and to specify new integrated three dimensional modeling software. The paper opens with a comparative economic review of precast construction internationally and in North America, which reveals that the market share of precast construction in North American is relatively low. The models are analyzed and aspects of the underlying management procedures that they reveal are discussed, such as types of contracting arrangements, cost estimating, design outsourcing, engineering design communication, mold design, product diversity, and quality control. The results highlight aspects of precast management processes that may be re-engineered through appropriate application of information technology. [ABSTRACT FROM AUTHOR]

A finite-element method (FEM) is used to simulate water wave propagation with large angle incidence at exterior boundaries. In this paper, the radiation boundary condition is expanded to a second-order approximation and a quadratic shape function is used in the FEM wave model. Cases used for verifications include wave scattering around a vertical cylinder and wave propagation over a submerged circular shoal with concentric contours. Numerical calculations based on this second-order radiation boundary condition are found to be in good agreement with theoretical and experimental results available. The numerical predictions show that this model has made a very good improvement over the first-order radiation boundary conditions for oblique wave incidence in coastal engineering. [ABSTRACT FROM AUTHOR]

In October of 1998, the ASCE Board of Direction adopted Policy Statement 465 supporting the concept of the master’s degree or equivalent as a prerequisite for licensure and practice of civil engineering at the professional level. Citing globalization, an intricate and complex infrastructure, and new engineering and information technologies, in October of 2001, the board unanimously voted to move forward with a revised Policy Statement 465, entitled “Academic Prerequisites for Licensure and Professional Practice.” This paper examines the ethical dimensions surrounding the call for additional education. To this end, the ASCE Code of Ethics will be discussed as a living document that governs the practice of safe, effective, and professional civil engineering, and will be brought to bear on the issues surrounding the implementation of ASCE Policy Statement 465. [ABSTRACT FROM AUTHOR]

Engineers face a unique situation with respect to reporting unsafe situations that are created by an employer or a client, in that licensed engineers may have a legal or an ethical duty to “blow the whistle” on an employer in certain situations. This paper covers several aspects of whistle-blowing as they relate to practicing engineers. In the first section of the paper, five engineers are presented who have recently sought legal protection as whistle-blowers. This is followed by an analysis of state engineering regulations and professional ethics codes that often encourage, or even mandate that licensed engineers report employers or clients to governmental authorities in certain situations where the public safety is endangered. The next section presents an overview of whistleblower protection laws. Finally, there is a presentation of the potential for civil liability for those engineers who fail to report certain unsafe situations. [ABSTRACT FROM AUTHOR]