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Water quality control bioretention cells are usually sized so that they are large enough to provide storage of runoff generated from its catchment resulting from the water quality control design storm of the location of interest. A bioretention cell can have three parts where runoff may be temporarily stored: (1) the depressed surface ponding area, (2) the growing media layer, and (3) the storage layer. In this study, the detailed sizing calculation methods adopted by 21 jurisdictions in the US and Canada were reviewed and compared. It was found that for satisfying the required storage volume to store runoff generated from the water quality control design storm, some jurisdictions only allow the storage provided by the surface ponding area to be counted, whereas other jurisdictions allow the sum of the storages provided by two of the three or all of the three parts to be counted. These differences can result in significant differences in the sizes and performances of bioretention cells. By examining and analyzing the detailed hydrologic processes involved in the operation of bioretention cells, it was demonstrated in this study that many of the adopted sizing calculation methods are flawed or inappropriate. Presented here are a summary of the findings and the recommended sizing calculation method. The possible degrees of over- or underdesigns resulting from some of the incorrect sizing calculation methods are also estimated. [ABSTRACT FROM AUTHOR]

In a composite section, in-plane shear strain in the slab (acting as a flange in the composite girder) under the applied bending causes the longitudinal displacements in the parts of the slab remote from the webs to lag behind those near the webs. This phenomenon, termed shear-lag, can result in an incorrect calculation of the displacement and extreme fiber stresses when using only the elementary theory of beam bending. The effective width concept has been introduced, widely recognized, and implemented into different codes of practice around the world as a simplified practical method for design and evaluation of structural strength and stiffness while accounting for shear-lag effects indirectly. Each code implements different ideas and approaches for specifying effective width. This paper proposes simpler and more versatile design criteria for computing the effective width (beff) in steel-concrete composite bridges. A parametric study was conducted based on finite-element analysis of bridges selected by a statistical method—namely, design of experiment concepts. Both simple-span and multiple-span continuous bridges were considered in the parametric study. The finite-element methodology was validated with companion experiments on 1/4- and 1/2-scale specimens. Effective width values at the critical sections were computed from stresses extracted from FEM models and used in developing candidate design equations. The final design criteria were selected based on assessment of impact of candidate equations. Use of full width—the most versatile, simplest, and sufficiently accurate effective width design criteria, is proposed for both positive and negative moment regions. [ABSTRACT FROM AUTHOR]

Underground concrete vaults have been and are planned to be used to store contaminated materials, such as hazardous materials and radioactive waste, over long periods of time. To protect humans from exposure to the contamination, the key to this long-term storage is immobilization achieved through designing concrete vaults with enhanced hydraulic performance. This paper evaluates concrete vault design parameters including properties of soil layers surrounding the vault, vault size, slope of the vault roof, and the amount of concrete degradation under various infiltration rates. A numerical model that estimates the flow of water through the vault is used as the computer simulation tool. Conclusions from the modeling simulations are that clay layers, including sand and loam layers forming a capillary barrier and placed adjacent to the vault concrete, were found to have a better hydraulic performance. Smaller vault sizes result in lower seepage through the vault and suggest a scale effect. Roof slope has a relatively small influence on hydraulic performance. [ABSTRACT FROM AUTHOR]

The incorporation of data from the physical environment allows a standard civil engineering probability and statistics course to double as an introduction to natural hazards. The requirement of a related term paper adds to the exposure. An established course, using such an arrangement, is described in this technical note. [ABSTRACT FROM AUTHOR]

In recent years important research activity has been undertaken in order to determine the earthquake performance of light gauge steel house structures. Usually, studies approach the problem of earthquake performance through experiments on wall panels conducted either under monotonic or cyclic loads. All studies underline the overwhelming importance that the behavior of the connections has in determining the overall performance of wall panels. However, although these studies focused on the global behavior of the panel, they did not try to characterize the behavior of and provide design criteria for connections, as components of the structural system, and to provide relevant design criteria. The present paper attempts to fill this gap. [ABSTRACT FROM AUTHOR]

Although pressure grouting beneath the tips of drilled shafts had been used successfully worldwide for close to 4 decades, it has remained relatively unused in the United States in part due to the absence of a rational design procedure. Previous international usage relied predominantly upon experience and unpublished proprietary approaches. More recently, research aimed at quantifying the improvement that could be derived from postgrouting drilled shaft tips has resulted in a design methodology. This paper briefly discusses the postgrouting process and outlines the full scale test programs used to identify parameters affecting postgrouting performance. Correlations developed between applied grout pressure and end bearing improvement are presented along with a numerical example illustrating the design procedure. [ABSTRACT FROM AUTHOR]

This study is divided into two parts. The first study determines window size and size reductions for different wall and ceiling reflectance combinations that are needed in a classroom to achieve one leadership in energy and environmental design (LEED) daylight factor credit. The second study determines the power consumption of indirect luminaires with a target illuminance of 538 lux for different wall and ceiling reflectance combinations. LEED credits for the optimizing energy performance are determined. It is found that ceiling reflectance has a higher impact on light levels and energy performance than wall reflectance. A ceiling reflectance of 90% and wall reflectance of 75% allows a minimum window-to-wall ratio of 0.444 to achieve one LEED daylight factor credit. The same room decreases lighting power density for an indirect fluorescent lighting system by one-third below the maximum permissible lighting power density specified in American Society of Heating, Refrigerating and Air-Conditioning Engineers/Illuminating Engineering Society of North America (ASHRAE/IESNA) Standard 90.1-2001. If lighting constitutes 50% of the total ASHRAE/IESNA 90.1 load, 0.92 LEED credits for the optimization of energy performance can be obtained for new construction and 2.92 credits can be obtained for existing buildings. [ABSTRACT FROM AUTHOR]

This paper presents an alternative project delivery system where there is a need for mass production of housing units while, at the same time, allowing recipients to finish the units in their own way to avoid the problem of them redoing the work if the units are not what they really need. Large numbers of the recipients of governmental houses in Kuwait tend to remodel their newly-awarded houses to fit their needs. When carried out on a large scale, this represents a waste of resources on public funding and imposes costs on the occupants of the government housing units. As a result, this paper suggests that the National Housing Authority (NHA) in Kuwait should consider delivering a “partially constructed houses system” to avoid the substantial rebuilding activities carried out by a large number of occupants. This study documents the effect of the partially constructed housing approach on reducing the waiting period and cost of construction, and on meeting recipients’ expectations. In addition, the study recommends different alternative options for when construction should be stopped by the NHA and then continued by the recipients to complete the houses to their own satisfaction. [ABSTRACT FROM AUTHOR]

A number of factors suggest engineering and construction professionals should discuss increasing designers’ role in construction safety. Design civil engineers could contribute to construction worker safety by performing five tasks differently than current custom and practice: reviewing their designs, creating design documents, assisting the owner in procuring construction, reviewing submittals, and inspecting work in progress. However, four sets of major barriers would prevent designers from increasing worker safety through these tasks: lack of safety expertise, lack of understanding of construction processes, typical contract terms, and professional fees. Potential ways for reducing these barriers are suggested. The United Kingdom regulations requiring engineers to design for safety are summarized, but it is concluded that similar legislation in the United States would not be appropriate. [ABSTRACT FROM AUTHOR]

The main objective of a project is to verify the requirements and target levels for values of reliability, functionality, and operationality during the useful life of the structure. Such requirements should be provided by external studies carried out by the promoter. In their absence, the engineer has to specify requirements using his or her own criteria. This paper describes a procedure that defines the target levels for maritime structures in terms of their general and operational intrinsic natures. These natures are used to evaluate the importance of the structure as a function of the economic, social, and environmental impact produced in case of serious damage or a total loss of functionality and stoppage, respectively. This procedure gives recommendations for values of a structure’s minimum useful life, joint probability of failure against the principal failure modes, adscribed to ultimate and serviceability limit states, minimum operationality, average number of admissible technical breakdowns, and maximum allowed duration of a stoppage mode. [ABSTRACT FROM AUTHOR]

This technical note presents an analysis of the hydraulic capacity of several bridges in a coastal area in Mexico, following cyclonic floods. The heights and lengths of the bridges and the flow rates of the rivers were the comparison parameters used. The analysis showed that for floods occurring within a 100-year return period these bridges were insufficient in length and/or height. A comparative graph shows that the failed and nonfailed bridges are clearly separated by a tendency line and its equation was obtained. Without intending this equation to be taken as a universal rule, its application could be a useful point of departure in reviewing the design of bridges in coastal areas. [ABSTRACT FROM AUTHOR]

Directional wave statistics can be used to optimize the design of offshore structures which are not symmetrical. Unfortunately there does not appear to be any consensus on how directional design criteria should be developed or used. Using simple examples, we show that commonly used methods are unconservative. In order to preserve the reliability given by designing to omnidirectional criteria, the product of the probabilities of nonexceedance from all of the direction bands must equal the omnidirectional probability. We suggest a simple method for assuring consistency between omnidirectional and directional criteria. [ABSTRACT FROM AUTHOR]

The accurate design of drip irrigation laterals needs to consider the variation of hydraulic head due to pipe elevation changes, head losses along the lines, and also, at a given operating pressure, emitter discharge variations related to manufacturing variability, clogging, and water temperature. Hydraulic head variations are consequent to both the friction losses and local losses due to the in-line or on-line emitters along the pipe, which determine the contraction and subsequent enlargement of the flow streamlines. Moreover, in-line emitters usually have a smaller diameter than the pipe, and therefore an additional friction loss must be considered. Evaluation of energy losses and consequently the design of drip irrigation lines is usually carried out by assuming the hypothesis that local losses can be neglected, even if previous experimental researches showed that local losses can become a significant percentage of total head losses as a consequence of the high number of emitters installed along the lines. This paper reports the results of an experimental investigation to evaluate local losses in integrated laterals in which coextruded emitters are installed inside the pipe. Local losses were measured for 10 different types of commercially available integrated laterals and for different Reynolds numbers. A practical power relationship was deduced between the α coefficient, expressing the amount of local losses as a fraction of the kinetic head, and a simple geometric parameter characterizing the geometry of the emitter and the pipe. Local losses obtained for integrated laterals were then compared with those due to the on-line emitters, previously determined as a function of the pipe-emitter geometry. The proposed criterion for calculating the local losses was finally verified by using a step-by-step procedure. [ABSTRACT FROM AUTHOR]

In the early days of the Reclamation Service, the criteria for irrigability of lands generally consisted of two elements: (1) is water available? and (2) can we get the water to the land? Within a few years, many of the early projects were experiencing reduced agricultural productivity and reduced ability to repay construction loans because the soils were becoming waterlogged and saline. By 1915, construction of subsurface drainage facilities had been initiated on several projects. However, at the time, subsurface drainage was more of an art than a science. Much of the world’s experience with agricultural drainage had been gained in humid areas which were quite different from arid areas. With no standards and limited knowledge of ground water movement, these early drainage efforts met with varying degrees of success. This paper summarizes the development of scientific methods to ensure successful application of drainage in a sustainable irrigated agriculture. Reclamation has introduced these methods to solve irrigated drainage problems at the international level. This paper will address the international experience, and how the same design and construction methods and procedures are now being used to design corrective drainage facilities for dams and other major structures and to support environmental enhancement programs. [ABSTRACT FROM AUTHOR]

The project inception stage has been the focus of intense research activity for a number of years. The need to establish the project parameters and performance requirements has been an imperative in many organizations. Predesign processes and activities are being instituted that work through client strategic and organizational issues, needs, and requirements before the design team is involved. The participation of stakeholders in predesign workshops is a common feature of these project inception approaches. These approaches prepare a clear and workable statement of the project requirements in performance terms that the client group has agreed and committed itself to. This document can then provide a sound basis for the development of the design. One approach to these early stages of the project is strategic needs analysis. This approach uses a workshop setting to focus stakeholder involvement in proposing and identifying a range of strategic options for the proposed project. A case study of strategic needs analysis involving university faculty relocation to a new site is presented. The developments of organizational strategic options are described with the development of user performance indicators to guide the design development process. [ABSTRACT FROM AUTHOR]