Prototype system for knowledge problem definition

Attitudes to knowledge management (KM) have changed considerably as organizations are now realizing its benefits. Implementation, however, has been facing serious difficulties attributed to either not being able to anticipate the barriers when planning KM strategies or to using inappropriate methods and tools for implementation. These difficulties are more critical in construction due to the fragmented nature of the industry. This paper suggests that proper definition of a KM problem at the early stages of developing the KM initiatives will result in better control over the KM barriers. A methodology for identifying KM problems within a business context is then introduced. The methodology is encapsulated into a prototype software system, which facilitates its deployment in organizations and provides online help facilities. The methodology, development, operation, and evaluation of the prototype are described. The paper concludes that the prototype offers considerable potential for delivering a clarified KM problem and a distilled set of issues for an organization to address. This represents a significant first step in any KM initiative

Finite-Element Analysis of Shear-off Failure of Keyed Dry Joints in Precast Concrete Segmental Bridges

This article has been made available through the Brunel Open Access Publishing Fund.The structural behaviour of precast concrete segmental bridges is largely dependent on the behaviour of the joints between segments. The current practice is to use small keys that are usually unreinforced, distributed over the height of the web and the flange of concrete segments and these keys are normally dry. In this study, a numerical analysis model was established based on ABAQUS finite element code to investigate structural behaviour of keyed dry joints under direct shear. The concrete damage plasticity model along with the pseudo-damping scheme were incorporated to analyse the system for microcracks and to stabilize the solution, respectively. The numerical model is calibrated by full-scale experimental results published elsewhere. It was found that the predicted ultimate load, cracking evolution history, and final crack pattern agree reasonably well with experiment results. The validated numerical model was then employed for parametric study on factors affecting shear behaviour of keyed dry joints, in this case confining pressure. It has been found that shear capacity predicted by AASHTO diverges from that predicted by numerical analysis at high confining pressure because the contribution of friction in the total shear capacity reduces with the increase in confining pressure. Hence, it is recommended to reduce the friction coefficient used in AASHTO code when high confining pressure is applied. Moreover, the propagation of inclined crack is arrested at high confining pressure due to the fact that the fracture propagation direction is governed by the criterion of the maximum energy release rate

Monitoring Earth Pressure Balance Tunnels in Los Angeles

ABSTRACT: Tunneling using earth pressure balance (EPB) tunneling methods has been active in Los Angeles over the last seven years. Three recent large-diameter EPB tunnel projects have been completed to create approximately 32km (20 miles) of precast concrete lined tunnel excavated through alluvial soils and soft, sedimentary rock. This paper addresses monitoring of ground surface subsidence using data collected from geotechnical instrumentation and TBM performance parameters. TBM operating data are used in conjunction with surface-installed instrumentation to predict surface subsidence. TBM operations may then be adjusted to reduce potential settlementrelated damage to adjacent structures or utilities. Monitoring instruments using remote access is also addressed. The paper provides case histories of successful performance monitoring to support future urban tunneling projects

State of the Art of Structural Engineering

Abstract: The objective of this paper is to provide an overview of the developments in structural engineering that took place during the past century. This overview includes ͑1͒ some of the major structural accomplishments as selected by the writers, ͑2͒ the advances in mechanics as the basis of structural analysis, ͑3͒ the development of new materials, ͑4͒ new fields of research and practice, and ͑5͒ the changes in the way design projects are performed. In addition, the writers' personal predictions for future developments during the 21st century are also presented. One of the main features affecting the evolution of structural engineering over the last part of the 20th century has been the advent and rapid development of digital computers as engineering tools. Computers can be used to perform complex and cumbersome computations and to enhance worldwide communications, both with great speed and reliability. This has already had an important effect on the way we design structures and educate civil engineers, but the impact on structural analysis and design as well as on construction planning and management is still in progress. We believe that this impact will be fully felt in the 21st century. Computers will liberate engineers from tedious and routine computations, allowing them to concentrate on more creative and important endeavors. They will facilitate the design of constructed facilities as complete systems rather than by considering each subsystem ͑such as structure and foundation͒ separately. They will lead finally to the needed integration of the design and construction processes

Combining dynamic relaxation method with artificial neural networks to enhance simulation of tensegrity structures

Abstract: Structural analyses of tensegrity structures must account for geometrical nonlinearity. The dynamic relaxation method correctly models static behavior in most situations. However, the requirements for precision increase when these structures are actively controlled. This paper describes the use of neural networks to improve the accuracy of the dynamic relaxation method in order to correspond more closely to data measured from a full-scale laboratory structure. An additional investigation evaluates training the network during the service life for further increases in accuracy. Tests showed that artificial neural networks increased model accuracy when used with the dynamic relaxation method. Replacing the dynamic relaxation method completely by a neural network did not provide satisfactory results. First tests involving training the neural network online showed potential to adapt the model to changes during the service life of the structure. DOI: 10.1061/�ASCE�0733-9445�2003�129:5�672

A study of two stochastic search methods for structural control

Abstract: Many engineering tasks involve the search for good solutions among many possibilities. In most cases, tasks are too complex to be modeled completely and their solution spaces often contain local minima. Therefore, classical optimization techniques cannot, in general, be applied effectively. This paper studies two stochastic search methods, one well-established �simulated annealing � and one recently developed �probabilistic global search Lausanne�, applied to structural shape control. Search results are applied to control the quasistatic displacement of a tensegrity structure with multiple objectives and interdependent actuator effects. The best method depends on the accuracy related to requirements defined by the objective function and the maximum number of evaluations that are allowed

Pipeline Engineering: How to Plan for Everything

Abstract Every large pipeline project has its own unique design elements and surprises. Anticipating and knowing how to prepare for these potential issues is critical to the successful design, construction and operation of the pipeline. During Preliminary Engineering for pipeline projects there are a few guiding principles that every team should follow to plan the project effectively. Since a thorough Preliminary Engineering evaluation is fundamental for a project's success, these guiding principles cannot be ignored. This paper provides the planning principles and a detailed checklist for owners and engineering managers to utilize during the planning stages of a major pipeline project. Utilization of these tools will help identify potential surprises encountered on each pipeline project earlier than before. These principles and checklist have been developed through experience of planning and design of over 400 miles of large diameter pipelines in mostly urban environments. Planning for everything may seem too cumbersome to accomplish, but this paper will simplify the process for a majority of the typical challenges and include examples from previous lessons learned

Effective stress analysis and set-up for shaft capacity of piles in clay

ABSTRACT A case history of repeated dynamic and static loading tests in Alberta on two pipe piles during dissipation of driving-induced pore pressures is presented together with three reanalyzed published case histories involving similar records. The four case histories demonstrate that, for each case, the same effective-stress proportionality coefficients, beta-coefficients, fit the capacities at different degrees of dissipation of excess pore pressures. For two of the test sites, the beta-coefficients back-calculated from the tests differed considerable from the values determined from the soil plasticity relation, while for two, the agreement is good. For one case, the backcalculated shaft resistance agreed well with the values of vane shear strength, while a less good agreement was found for the other tests. Neither case showed good agreement was found for methods combining undrained shear strength and effective overburden stress. Capacity calculations for two cases employing methods based on CPT soundings gave excellent agreement with one test and a poor agreement with the other. The increase of capacity due to aging after dissipation of excess pore pressures did not agree with cited recommendation for calculations of aging effect

Fail-safe optimization of viscous dampers for seismic retrofitting

This paper presents a new optimization approach for designing minimum-cost fail-safe distributions of fluid viscous dampers for seismic retrofitting. Failure is modeled as either complete damage of the dampers or partial degradation of the dampers' properties. In general, this leads to optimization problems with large number of constraints. Thus, the use of a working-set optimization algorithm is proposed. The main idea is to solve a sequence of relaxed optimization sub-problems with a small sub-set of all constraints. The algorithm terminates once a solution of a sub-problem is found that satisfies all the constraints of the problem. The retrofitting cost is minimized with constraints on the inter-story drifts at the peripheries of frame structures. The structures considered are subjected to a realistic ensemble of ground motions, and their response is evaluated with time-history analyses. The transient optimization problem is efficiently solved with a gradient-based sequential linear programming algorithm. The gradients of the response functions are calculated with a consistent adjoint sensitivity analysis procedure. Promising results attained for 3-D irregular frames are presented and discussed. The numerical results highlight the fact that the optimized layout and size of the dampers can change significantly even for moderate levels of damage