Performance-Based Design Approach in Seismic Analysis of Bridges

The seismic design requirements used in the United States are based on the recommendations of the American Association of State Highway and Transportation Officials. These requirements are primarily based on the importance of the structure, the level of deformation imposed on the structure, soil conditions, and the ductility of structural members, especially piers and supports. In the performance-based design approach, the design is primarily focused on meeting a performance objective, which is in line with a desired level of service. Currently, the effort toward implementing the performance-based design approach in buildings is under way in the United States. The seismic performance criteria for buildings have been established and reported by various organizations. It seems that at least three levels of performance, ranging from “fully operational” to “near collapse” can be used to meet the postearthquake conditions, safety, usage, and occupancy for the varous levels of service expected from all types of structures. In this paper a critical evaluation of these performance criteria and their relevance to highway bridge design, in conjunction with the current design practice, is discussed. Various types of designs such as those based on strength, deformation, nonlinear behavior, and energy, which can be used to meet the specified performance levels in seismic design of highway bridges, are also discussed in the paper. Examples of real applications of the method in highway bridges are reviewed. Furthermore, the procedure by which the performance-based method has been implemented in these example cases is described and discussed in the paper.     

Integrated Decision Support System for Optimal Renewal Planning of Sewer Networks

Municipalities are under increasing pressure to adopt proactive and optimized renewal strategies to reduce the risks, life-cycle costs, and resources needed to maintain acceptable performance and service levels of their infrastructure assets. A new integrated approach for optimal renewal planning of municipal infrastructure systems has been developed. This paper discusses the application of the proposed approach to implement a GIS-based decision support system (DSS) to support the renewal planning of sewer networks. Condition rating, risk assessment, and prioritization techniques are described. A procedure for identifying and selecting the most suitable renewal technologies is also presented. A genetic algorithm-based multiobjective optimization technique is used to find a Pareto front of feasible solutions, each comprising a set of sewers to be renewed each year, along with the associated costs and expected benefits in terms of condition improvement and risk reduction. The paper also presents an example application of the prototype DSS on the sewer network in Regina, Canada.     

Medical Records for Building Health Management

Medical records provide essential information for evaluating a patient’s health. Without them, it would be difficult for doctors to make accurate diagnoses. Similar to diagnoses in medical science, building health management also requires building medical records for making accurate diagnoses. At later stages of a building’s life cycle, when the budget is limited, organizations responsible for building repairs and maintenance are unable to digitalize building health diagnoses and keep complete medical records of buildings; as a result, maintenance crews usually cannot fully understand buildings’ overall health conditions and their medical histories, which may result in erroneous diagnoses directly or public safety dangers indirectly. Using the problem-oriented medical record adopted for the medical diagnosis of human diseases, this paper designs a building medical record (BMR), which allows simple electronic archiving, and evaluates its practicability with a case study of school buildings. The purpose of a BMR is to enable maintenance engineers (building doctors), building managers, and contractors of school buildings to have low-cost access to required information for making complete evaluations and maintenance suggestions for buildings.     

Serviceability of Materials in the Tropics

With increasing complexity in the building construction trend and the advancement of building material technology, more building materials and substitutes have evolved and been adopted for use to function together in a building that is supposed to maintain its technical performance during its intended working life. Condition surveys of 450 buildings, face-to-face interviews, and workshops were conducted with industry specialists, to examine the behavior of materials used in facades and wet areas in tropical climates and their estimated costs of maintenance. This paper presents an indicative computational method for the durability of building materials for fa?ades and wet areas in the tropics. Total operations and maintenance costs of the identified materials are also included to provide suggestive maintenance expenditure over the materials’ service life. Natural stone was preferred as a more durable fa?ade material while ceramic and homogeneous tiles proved more economical for wet areas.     

Formal Definition of a User-Adaptive and Length-Optimal Routing Graph for Complex Indoor Environments

Car routing solutions are omnipresent and solutions for pedestrians also exist. Furthermore, public or commercial buildings are getting bigger and the complexity of their internal slructure has increased. Consequently, the need for indoor routing solutions has emerged. Some prototypes are available, but they still lack semantically-enriched modelling (e.g., access constraints, labels, etc.) and are not suitable for providing user-adaptive length-optimal routing in complex buildings. Previous approaches consider simple rooms,concave rooms, and corridors, but important characteristics such as distinct areas in huge rooms and solid obstacles inside rooms are not considered at all, although such details can increase navigation accuracy. By formally defining a weighted indoor routing graph, it is possible to create a detailed and user-adaptive model for route computation. The defined graph also contains semantic information such as room labels, door accessibility constraints, etc. Furthermore, one-way paths inside buildings are considered, as well as three-dimensional building pans, e.g., elevators or stairways. A hierarchical structure is also possible with the presented graph model.     

A comparison of inclusive and restrictive strategies in modern missing data procedures.

Two classes of modem missing data procedures, maximum likelihood (ML) and multiple imputation (MI), tend to yield similar results when implemented in comparable ways. In either approach, it is possible to include auxiliary variables solely for the purpose of improving the missing data procedure. A simulation was presented to assess the potential costs and benefits of a restrictive strategy, which makes minimal use of auxiliary variables, versus an inclusive strategy, which makes liberal use of such variables. The simulation showed that the inclusive strategy is to be greatly preferred. With an inclusive strategy not only is there a reduced chance of inadvertently omitting an important cause of missingness, there is also the possibility of noticeable gains in terms of increased efficiency and reduced bias, with only minor costs. As implemented in currently available software, the MI approach tends to encourage the use of a restrictive strategy, whereas the MI approach makes it relatively simple to use an inclusive strategy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Computer-Aided Healthcare Facility Management

The decision-making process in the field of health-care facility management is multifaceted and encompasses many different areas, including maintenance, performance, risk, operations, and development. Information and communications technologies are perceived as the interface that integrates these topics. The main objective of this research is to develop a decision-support system based on core parameters affecting the performance of health-care facilities. This paper presents the preliminary development of a quantitative integrated health-care facility management model, subdivided into the following three interfaces: input, reasoning evaluator and predictor, and output. The model proposes the following five modules: maintenance, performance and risk, energy and operations, business management, and development. It offers projection of maintenance costs, performance, and risk of built facilities in the health-care sector. The model hypotheses are that age, occupancy, and environment affect the maintenance of the facility. These factors are quantitatively developed and analyzed for performance-based maintenance planning, employing an occupancy coefficient and a projection of performance indicator. Simulations of the facility coefficient for different combinations of occupancy and environment reveal that the occupancy level is a major factor that causes an augmentation of more than 18% in the allocation of resources for maintenance compared with standard occupancy. Prediction of the performance score of a building is carried out using a nonlinear pattern for the structural components and linear patterns for the rest of the components.     

Continuous Value Enhancement Process

The demand for sustainable buildings is an important emerging trend in the building industry. However, the task of delivering these facilities is more difficult than for traditional projects and existing project management techniques struggle to handle the high levels of complexity present. A process-based model, called the continuous value enhancement process (CVEP), was developed to systematically generate and evaluate project alternatives leading to high performance solutions that improve project performance and increase levels of sustainability. Developed specifically to address the challenges facing the Pentagon renovation—which will become the world’s largest green office renovation—CVEP is tested to research its ability to support project management decision making in ways that elevate sustainability and project performance. The key contributions of this model include the integration of sustainable objectives into project management practices, and the development of a metric for measuring the quality and focus of project team decisions.     

Measuring the financial impact of employee attitudes.

Presents a new approach for attaching behavioral costs to attitudes, based on data from 169 bank tellers (average age, 30 yrs). Attitudes were measured through an employee survey; behavioral measures were constructed based on company records. Behavioral costs per employee were assigned through cost-accounting techniques. Attitudes were correlated with future behavior, the behavioral changes associated with attitudinal shifts were estimated, and new behavioral costs per employee were computed. Results show expected direct-cost savings of $17,664 in absenteeism, turnover, and performance from a .5 standard deviation increase in job satisfaction; savings associated with enhanced job involvement and motivation are also reported. A critical analysis of the approach used is presented, as is a discussion of its usefulness to organizations. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hybrid Models of Neural Networks and Genetic Algorithms for Predicting Preliminary Cost Estimates

This technical note applies hybrid models of neural networks (NN) and genetic algorithms (GA) to cost estimation of residential buildings to predict preliminary cost estimates. Data used in the study are for residential buildings constructed from 1997 to 2000 in Seoul, Korea. These are used in training each model and evaluating its performance. The models applied were Model I, which determines each parameter of a back-propagation network by a trial-and-error process; Model II, which determines each parameter of a back-propagation network by GAs; and Model III, which trains weights of NNs using genetic algorithms. The research revealed that optimizing each parameter of back-propagation networks using GAs is most effective in estimating the preliminary costs of residential buildings. Therefore, GAs may help estimators overcome the problem of the lack of adequate rules for determining the parameters of NNs.     

Strategies for Wind Damage Mitigation—Summary

Wind damage to buildings and structures in the United States costs approximately $4 billion a year, mostly to nonengineered buildings. Civil engineers should help identify structural problems (weak links) in these buildings and effective ways to correct the problem so that improved building codes and better construction practices can result in a reduction of damage. Strategies for mitigation involve many facets, such as educating the public that much can be done to reduce wind damage with minor improvement of buildings and minor cost increases; disseminating research findings and new knowledge to engineers, architects, builders, contractors, insurance companies, building code officials, and the public; incorporating key research findings into building codes and common practice; improving code enforcement; providing incentives through insurance‐premium reduction; and intensifying research to identify the most effective and economical ways to improve building performance. An international effort to share information and knowledge in wind‐disaster mitigation—the concept of International Decade of Disaster Mitigation, proposed by Dr. Frank Press, President of the National Academy of Science—should also be part of a global strategy.     

Building Maintainability—Review of State of the Art

This paper reviews the issue related to maintainability of building and discusses works of researchers worldwide. The paper offers two approaches that could be integrated with the concepts of maintainability to augment building performance throughout its economic life. The two approaches are: (1) total quality approach via performance audit and (2) life cycle cost (LCC) approach. Various systems constructed to enhance quality delivery and maintainability of buildings were also discussed. An attempt to integrate building performance and LCC in Singapore to improve the maintainability of buildings was presented.     

Discussion of Criteria for Prioritization of Predictive Maintenance of Building Fa?ades: Survey of 30 Experts

The practice of predictive maintenance depends significantly on the diagnosis of in-service performance and on the decision criteria for the selection of maintenance tasks. The definition of these criteria is limited because several actors are involved, each with their own perspectives of performance and maintenance needs. This paper discusses a set of 17 criteria to help the maintenance choice for building fa?ades, from three viewpoints: physical performance, risk, and costs. A group of experts was surveyed and 30 answers were received. Therefore, each criterion will be discussed according to the answers collected. The relative importance (using quantitative weights) and subclasses for each criterion are proposed.     

Simulation Model for Determining Maintenance Staffing in Higher Education Facilities

Expeditious repair of the unpredicted breakdown of the systems components of facilities is a crucial demand that is highly conducive to the convenience of users and to the longevity of systems. The determination of maintenance staffing, particularly the number of maintenance crews, constitutes a key decision in this regard. Judicious determination of the number of crews prevents crews from being underused or overloaded. A simulation model, using AweSim simulation language, was developed to determine the optimal number of crews for the maintenance department of a large higher education facility. The model development involved: establishing statistical distributions that reflect the stochastic nature of the generation of the repair requests as well as the service times; setting up the maintenance service model that defines the logic, sets priorities for assigning repair requests to crews, and defines performance measures; developing the simulation software; and collecting statistics of the performance measures for scenarios that represent different number of crews and crew-loading policies. The optimal number of crews was identified as being the scenario of the lowest total of the operating costs incurred by the maintenance department and costs of inconvenience to users. Finally, the model represents a robust management tool for long-term economic planning of resources.     

Influence of Project Type and Procurement Method on Rework Costs in Building Construction Projects

While it is widely recognized that additional costs due to rework can have an adverse effect on project performance, limited empirical research has been done to investigate the influencing factors. The research presented in this paper aims to determine the influence of different project types and procurement methods on rework costs in construction projects. Using a questionnaire survey, rework costs were obtained from 161 Australian construction projects. The direct and indirect consequences of rework are analyzed and discussed. It is shown that, contrary to expectation, rework costs do not differ relative to project type or procurement method. In addition, it was found rework contributed to 52% of a project’s cost growth and that 26% of the variance in cost growth was attributable to changes due to direct rework. To reduce rework costs and therefore improve project performance, it is posited that construction organizations begin to consider and measure them, so that an understanding of their magnitude can be captured, root causes identified, and effective prevention strategies implemented.     

Recommendations for a cost-offset model of psychotherapy allocation using generalized anxiety disorder as an example.

As inexpensive interventions gain empirical support, there is an increasing risk that such data may be used by health maintenance organizations to unfairly restrict the number and type of therapy sessions reimbursed for all clients, even those less likely to benefit from economical treatments. As a result, it is important to identify clients who may not respond to specific therapies and to empirically support ways to treat them. Successful treatment of nonresponders is also valuable because predictors of treatment failure tend to predict cost related to medical and disability expenses. Using generalized anxiety disorder as an example, this article suggests a flexible and comprehensive approach to cost-benefit analysis in psychotherapy that includes clients who may not improve in response to current data-based interventions. In addition, suggestions are made for the identification of alternative treatment approaches, and a potential treatment allocation model is recommended. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Integrated Model for Optimizing Strategic Overhaul Planning of Distributed Pump Stations

An important part of the lifecycle costs for pump stations are the support costs associated with energy and preventive maintenance of the pumps. Both cost terms are interrelated because a trade-off exists between maintaining pumps frequently (with increased pump efficiency, reduced energy costs and increasing maintenance costs, and pump unavailability) and extending the intervals between the overhauls (increased loss of efficiency, increased energy costs, and decreased maintenance costs). The planner needs to forecast pump overhaul demands to determine budget levels because economic resources are limited. This process is assisted by using mathematical programming methods to prioritize funding for equipment requiring renewal in consideration of limited resources in a strategic time horizon (several years). This work proposes an efficient model to define an overhaul maintenance program for a pump network with a large number of pumps (a few hundred in the case study). The model minimizes the discounted total (energy+overhaul) cost by selecting and scheduling pumps for overhaul subject to budget constraints. The formulation uses 0–1 integer programming.     

Probability-Based Bridge Network Performance Evaluation

This paper presents a comprehensive mathematical model for evaluating the overall performance of a bridge network based on probability analyses of network connectivity, user satisfaction, and structural reliability of the critical bridges in the network. A bridge network consists of all nodes of interest in a geographical region. These nodes of interest are connected to each other through multiple paths. The network performance evaluation in terms of connectivity is formulated by using an event tree technique. The network performance measure of user satisfaction deals with traffic demand and capacity of each link in the network. Moreover, the shortest paths in terms of total traffic costs are identified by network optimization algorithms for each pair of the origin and destination nodes of interest under the specified traffic demands. Using this information, the minimum-weight spanning tree (MST) that consists of the identified shortest paths is constructed. The bridges associated with MST are defined as the critical bridges in the network. The network performance in terms of structural reliability of the critical bridges can be computed from system reliabilities of the critical bridges by using a series-parallel system model. Finally, by combining the above three criteria, a single numerical measure is proposed to evaluate the overall performance of the bridge network. This novel approach is illustrated on a group of fourteen existing bridges with different reliability profiles located in Colorado. This study provides the basis of a network-level bridge management system where lifetime reliability and life-cycle costs are the key considerations for optimal bridge maintenance strategies.