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This paper presents the results of experimental testing of block masonry prisms and wallettes under uniaxial compression. The compressive load was applied in a direction perpendicular or parallel to the bed joints. Masonry prisms and wallettes were tested in the former direction, whereas only wallettes were tested in the latter direction. No influence of mortar strength or block thickness was observed on the cracking and failure patterns of specimens of similar type, although material crushing and spalling was marginally influenced by block strength. The cracking load for the assemblages tested normal to the bed joint was nearly 90% of the peak load capacity and higher as compared to 70% of the peak load capacity for the wallettes tested parallel to the bed joints. Similar load capacity and elastic modulus were observed for the prisms and wallettes tested normal to the bed joints. Whereas the strength for the wallettes tested parallel to the bed joints was 49%–83% less compared to those tested normal to the bed joints, their elastic modulus was nearly 25% higher. The experimental strength and strain values were compared with the existing analytical methods, which correlated well. [ABSTRACT FROM AUTHOR]

This paper presents a framework for assessing the reliability of fiber reinforced polymer (FRP)–strengthened reinforced concrete (RC) beams in flexure using stochastic nonlinear finite-element (SNFE) analysis and k-w-means clustering, based on active-learning kriging Monte Carlo simulation (AK-MCS), in which spatial variations in the concrete and bond material properties are considered. A computer algorithm was developed to augment commercially available nonlinear finite-element (FE) analysis software and automate the process for conducting the SNFE clustering-based AK-MCS analysis. The k-w-means clustering was based on the U learning function to provide multipoint enrichment to improve convergence of the stopping criteria by allowing parallel computation of the SNFE models. Parametric analysis indicated the accuracy of the reliability prediction of the examined member and proved the efficiency of the proposed analysis in reducing the number of calls to SNFE models compared with data in the existing literature, when using probability-based stopping criteria. Practical Applications: The quality of the FRP-to-concrete bond is affected by the integrity of the concrete at the interface, which varies across the dimensions of the strengthened member, causing added uncertainty in predicting the structural response, and hence the reliability of the FRP-strengthened member. This study proposes a computationally efficient approach to assess the reliability of FRP-strengthened concrete members by considering the spatial variation in the concrete properties (compressive strength, tensile strength, bulk modulus) and the quality of the FRP-to-concrete bond (shear and normal bond strength) by using an adaptive machine-learning technique. The proposed framework may be utilized by engineers to design FRP-strengthening systems for concrete members experiencing variation in the concrete properties due to poor quality control or active deterioration. [ABSTRACT FROM AUTHOR]

Despite the increasing recognition of the potential of Circular Economy (CE) strategies, their effective application to decarbonize the construction value chain faces multiple challenges. Ambiguity surrounding CE, stemming from a lack of clarity on actionable strategies, is a common concern. Existing studies lack a holistic approach for systematically integrating CE principles throughout the construction value chain, resulting in a scarcity of information on how to practically adopt CE within projects. This research aims to accelerate CE adoption by creating a value chain-structured portfolio of CE strategies and analyzing the implementation of such strategies in actual projects. To this end, a portfolio of CE strategies was compiled in a value chain-based-structure, which was evaluated against 71 US-based projects of exemplary sustainability criteria to scrutinize their successful implementation. Additionally, the study examined the interconnections and network dynamics among these strategies through association rule mining, network, and statistical analysis techniques. Results revealed a pronounced focus on strategies within the design, construction, and end-of-life value chain phases, with significant gaps existing in areas related to project financing, planning, logistics, property market, and operations. "Requiring sustainability certifications, standards, or labels" emerged as the most pivotal strategy in terms of frequency and number of associations, highlighting owners' significant role in CE transition. This study contributes to the body of knowledge by providing practical guidance and insights for industry practitioners in terms of actionable CE strategies and their state of implementation, ultimately fostering a more sustainably built environment. [ABSTRACT FROM AUTHOR]

Recycled gypsum powder from waste drywalls is a new alternative that has been recently introduced for partial cement replacement in concrete for construction applications. It has been shown that the recycled gypsum, alongside fly ash, can partially replace cement in concrete to some extent without hurting the required properties of concrete. In this paper, the impact of recycled gypsum content on the durability of concrete (hereafter called gypsum concrete) exposed to different environmental exposures is evaluated. A total of 153 concrete cylinders (100×200 mm) with different recycled gypsum contents (0%, 10%, and 20% of cement replacement) were considered. Each mix was exposed to air-dry, freshwater, seawater, freshwater–air dry cyclic, and seawater–air dry cyclic conditions. The specimens were tested in compression loading after 1,000, 3,000, and 6,000 h of exposure. Recycled gypsum used in this research was in two types of a powder with fine particles only (hereafter called fine gypsum) and in the form of mixed fine, coarse, and paper particles (hereafter called whole gypsum). Other mechanical and physical properties of concrete such as absorption, volume change, and ultrasonic pulse velocity were analyzed. It was observed that the compressive strength of the specimens with 10% and 20% fine gypsum content at Day 28 was about 36% and 40% lower than that of the control specimens, respectively. However, the strength gap was reduced to about 16% and 7% at the end of 6,000 h in the air-dry condition. The specimens submerged in freshwater and seawater showed a rate of strength gain higher than that of the control specimens, bringing the compressive strength of the gypsum concrete specimens slightly higher than that of the control specimens after 6,000 h exposure. Overall, recycled gypsum in combination with fly ash not only does not hurt the long-term strength of concrete but also can enhance the strength under certain conditions, mostly those exposures involving water exposure. [ABSTRACT FROM AUTHOR]

One of the obstacles to the recent trend toward taller timber buildings is the limited load-carrying capacity of softwood columns. With the aim of promoting the structural use of European beechwood (Fagus sylvatica L.) in high-performance applications, the buckling behavior of beech glued-laminated timber (GLT) columns reinforced with glued-in steel bars was investigated experimentally and numerically. Axial compression experiments were carried out on full-scale stocky and slender columns, and a finite-element model was developed and validated against the experimental data. The influence of geometric and material parameters on the load-carrying capacity of the steel-reinforced beech GLT columns was studied in parametric analyses. The experimental and numerical data demonstrate the high potential of this new structural product for high-strength columns in demanding residential, office, and industrial applications. The load-carrying capacity mainly depends on the cross section size, the column slenderness, the position and diameter of the reinforcement bars, and the initial deformed shape of the column. An eccentric layout with steel bars in the corners of the cross section is very effective in increasing the load-carrying capacity. Four corner steel bars of 20 mm diameter, 50 mm edge distance, and grade ST900/1100 were found to increase the load-carrying capacity of a 200-mm-wide square GL48h column by almost 40% across the slenderness ratios relevant to structural applications. The glued-in steel reinforcement is also expected to be able to provide an alternative load path for structural robustness, by enabling the columns to carry tensile forces. A design method for corner-reinforced beech GLT columns under axial compression was developed based on the empirical and numerical data. [ABSTRACT FROM AUTHOR]

Railways constructed in cold regions can experience localized frost heave in the winter as well as track softening during the spring thaw. These phenomena are great challenges for road and railway foundations on seasonally frozen ground and must be considered by railway operators. To address these problems, temporary wooden shims can be used to smooth existing tracks; reductions in train speeds may also be mandated. The degree of susceptibility of a given section of a track to frost can be determined by considering the main preconditions allowing heave and frost to occur. This study reviews several frost susceptibility surveys that show the correlation between soil properties and laboratory results of frost heave tests. A summary of treatment methods for frost action is presented and a straightforward design procedure is provided to first evaluate the frost susceptibility of soils and the frost hazard potential in Canada as well as predict the frost penetration depth, and then select the appropriate frost-treatment method based on previous studies and standards. The outcome of this study is a five-step tool that can be applied by Canadian engineers to first evaluate the frost susceptibility degrees of soils based on the soil properties in each province and then select the appropriate treatment method considering the frost hazard potential. [ABSTRACT FROM AUTHOR]

In this work, we analyzed the locations of existing bus stops in the Halifax Regional Municipality (HRM) area and then calculated the walking distance in time in order to understand the accessibility for pedestrians. In doing so, we employed geographic information systems (e.g., spatial and network analysis tools) to generate accessibility models from bus stops at 5, 10, 15, and 20 min of walking distance. After generating the service area of bus stops on maps, we overlaid socioeconomic variables (i.e., age group, income, and bus-stop accessibility) to better understand the HRM public transport network. We found that population density was an important consideration in providing the number of bus stops in specific communities, which may be related to the facilities offered by the urban hierarchy. Furthermore, we established a relationship between transit stops and accessibility for people in age groups of between 0 and 19 (e.g., school-going children) and 65+ (i.e., the older population) so as to obtain an understanding of the time required for them to access the bus stops on foot. Overall, 77% of the population in the HRM was served by public transport within 5 min of walking; however, for the 65+ cohort, this number was higher (82%). A significant amount of the young population (23%) was served over longer distances than 10′ of walking. We summarize that our findings are critical for planners, practitioners, and researchers in order for them to understand the present transit system in place based on accessibility to the bus stops within walking distance. [ABSTRACT FROM AUTHOR]

Glass fiber-reinforced polymer (GFRP) bars are used as internal reinforcement in many structural applications. The structural performance of GFRP-reinforced concrete elements is dependent on the physical and mechanical properties of GFRP reinforcement. There is a lack of experimental data on the flexural behavior of concrete beams reinforced with ribbed GFRP bars. This study evaluates the flexural strength and serviceability performance of concrete beams reinforced with ribbed GFRP bars. A total of 11 GFRP-reinforced concrete beams with dimensions of 4,350 × 400 × 200 mm (length × height × width) were constructed and tested under a four-point loading test setup. The main test parameters were the concrete cover, reinforcement ratio, bar spacing, and confinement due to the transverse reinforcement in the bending zone. The results uantify the effect of increasing the reinforcement ratio on the increase in the ultimate capacity and the reduction in deflection at the service and ultimate stages. In addition, the results showed that the increase in the confinement in the bending zone due to closely spaced stirrups resulted in a higher ductility index and ultimate capacity with no considerable effect on the postcracking stiffness of the beams. Moreover, based on the experimental results, the accuracy of deflection equations available in design codes and guidelines is evaluated and discussed. [ABSTRACT FROM AUTHOR]

Angle-ply (±55°) fiber-reinforced polymer (FRP) tubes are widely available and have been used in concrete-filled FRP tube (CFFT) members. Two observations have been reported regarding the behavior of these tubes in tension: a remarkably nonlinear stress–strain response and a significant increase in their tensile strength and stiffness when filled with concrete. To better understand these phenomena, a robust finite-element model is developed using LS DYNA software and validated against a diverse experimental database. It showed that the nonlinear behavior of the tube is mainly due to matrix cracking perpendicular to the fibers and to a lesser extent due to in-plane shear along diagonal bands. Concrete filling restrains the large radial and circumferential contraction of the hollow tube under longitudinal tension, thereby generating significant hoop tensile stresses and consequently a state of biaxial tensile stress. A failure envelope under such stress combination was developed and far exceeded uniaxial strength in either direction. A parametric study was performed on 68 new models with various properties. The longitudinal tensile strength (σmax) of CFFT tubes with fiber angles (θ) relative to longitudinal axis of 35°, 45°, 55°, 65°, and 75° increased 2.9, 4.1, 3.3, 2.8, and 1.4 times, respectively, that of hollow counterparts. Design-oriented equations were developed to represent the enhanced longitudinal bilinear stress–strain curve when the tube is filled with concrete. It can be used for flexural strength calculations of CFFTs, which would otherwise be grossly underestimated if calculated using hollow tube properties reported by the manufacturer or established from longitudinal coupon tests or from classical lamination theory. [ABSTRACT FROM AUTHOR]

In North American steel design specifications, a directional strength-enhancement factor is used to increase the predicted strength of fillet welds subjected to transverse loading (i.e., loading at 90° to the weld axis). Committees have expressed concerns about this factor being unsafe for single-sided fillet welds; however, due to a lack of testing, only cautionary statements have been made in most specifications to address this. An experimental program was hence developed to test 40 transversely loaded single-sided fillet welds in cruciform connections subjected to branch axial tension. The connections varied weld size, branch-plate thickness, and loading eccentricity to investigate the effects of these parameters on fillet-weld strength. Results of this program are presented herein, and a first-order reliability method (FORM) analysis was performed. It is shown that current fillet-weld design provisions meet/exceed code-specified target safety indices (i.e., β=4.0) provided that (1) the directional strength-enhancement factor is not used, and (2) stresses that result in opening of the weld root notch are avoided. [ABSTRACT FROM AUTHOR]

Highway bridge piers could be underdesigned for a multihazardous condition involving vehicle collision and air blast based on the current design code. The piers are often positioned in such a fashion that it is neither possible nor economically feasible to place protective devices around them. This paper numerically investigated two potential strengthening techniques, the placement of a fiber-reinforced polymer (FRP) wrap and polyurea coating onto the column surface, to improve column resistance against the extreme demands from combined collision and blast loads. Finite-element models of isolated reinforced concrete (RC) columns with an FRP wrap and polyurea coating were developed using a commercial software, LS-DYNA. The modeling techniques were validated separately against impact and blast experimental results. Collisions were supplied from a medium-size F800 single-unit truck at various velocities, and air blasts of varying magnitude were represented using the arbitrary Lagrangian–Eulerian approach. Bare and strengthened column response to various collision and blast demands was compared to assess the effectiveness of strengthening. The results indicated that using the FRP wrap and polyurea coating on columns could effectively mitigate the effects of combined vehicle collision and air blast. The effectiveness of each scheme differed as a function of geometric and material properties and column demands. Parametric studies were then conducted to evaluate the influences of various design parameters on column performance and identify optimal strengthening schemes. [ABSTRACT FROM AUTHOR]

The aim of this paper is to check the accuracy of analytical capacity models available for the prediction of out-of-plane strength of unreinforced masonry (URM) infill walls. The accuracy of the available models is checked by detailed comparison with the existing experimental results. In doing so, both types of capacity models are evaluated: Type I for the prediction of the strength in the undamaged state, and Type II for the prediction of strength reduction in the in-plane damaged state. Results from the calculations are discussed, and the best among the available models are recommended. Furthermore, the influence of orthotropy of the infill masonry in the out-of-plane capacity predicted by the models is discussed. The paper also highlights the prospect of using the capacity models in the cases of infill-beam gap and infill with openings. In the paper, the best pairs of models (composed by a model for the prediction of the out-of-plane strength in the undamaged state and a model for the prediction of the reduction of the out-of-plane strength in the damaged state, not necessarily provided by the same author) for URM infill walls, are suggested for the first time. [ABSTRACT FROM AUTHOR]

In the seismic performance assessment of reinforced concrete (RC) frames, a reliable estimation of the capacity of unreinforced masonry (URM) infill walls is of utmost importance to ensure structural safety conditions. With particular attention to the out-of-plane (OoP) capacity of URM infill walls after in-plane (IP) damage, the issue of defining reliable analytical prediction models for the assessment of the capacity is an ongoing study. In this paper, empirical equations are proposed for the evaluation of the infilled frame's OoP capacity, with or without IP damage, based on an extensive numerical parametric analysis, focusing on the influence of the key parameters that govern the mechanical model. The OoP capacity of URM infill walls, considering the variation in their geometrical and mechanical properties, was evaluated by using a macroelement model. The OoP strength was found to be largely influenced by the compressive strength, slenderness ratio, aspect ratio, and, additionally, level of IP damage. The reduction of OoP strength and stiffness due to IP damage was largely governed by the strength and the slenderness ratio of the URM infill wall. The reliability of the proposed model was also proved by comparisons with experimental results and some of the analytical models already available in the literature. The proposed equations provide reliable estimates of the OoP capacity by strongly indicating the suitability of the adopted macroelement model in capturing the OoP response of URM infills. [ABSTRACT FROM AUTHOR]

In this study, the performance of slender circular concrete columns strengthened with a novel hybrid system of longitudinally bonded prefabricated fiber-reinforced polymer (FRP) laminates and transverse FRP wrapping is investigated. The novelty of the hybrid system is to improve the load-carrying capacity of slender steel-reinforced concrete (RC) columns under eccentric axial compression by providing high modulus longitudinal carbon FRP (CFRP) laminates through enhancing the flexural stiffness of the slender column and to laterally support the longitudinal laminates by FRP wraps to prevent debonding and local buckling. A total of 6 large-scale circular slender RC columns with a diameter of 260 mm and a length of 3,048 mm were tested under combined axial and flexural loads. The results showed that, for the strengthening of the slender columns, the hybrid system is a more effective strengthening system than wrapping controlling second-order deformations due to the slenderness effect and enhancing the load-bearing capacity. Also, the performance of the system was further investigated using an analytical-numerical model considering the second-order deformations of the slender columns. The model considered nonlinearity in material and confinement effects plus the geometrical nonlinearity via an iterative second-order analysis. The model was verified against experimental data from the current study (hybrid system) and an independent study (wrapping system) and showed a good agreement with the test results. Then, a comprehensive parametric study was conducted to study the effect of various parameters including slenderness ratio, load eccentricity, longitudinal and transverse FRP reinforcement ratios, concrete strength, and column diameter on the performance of slender RC columns strengthened with the hybrid system. It was found that the hybrid strengthening system was more effective for RC columns with high slenderness ratios, high load eccentricities, and low concrete strength. [ABSTRACT FROM AUTHOR]

With about $10 trillion spent on construction-related goods and services every year worldwide, advancing the construction industry, one of the largest sectors in the world economy, becomes crucial. Diffusing building information modeling (BIM), one noticeable advancement in construction process modeling, has been the objective of many academic studies as well as state-of-the-review literature. Deviating from approaches of other studies, this research paper presents a novel conceptual analysis and a critical review of the barriers to BIM adoption in the construction industry. This study looks first at the mechanisms of BIM diffusion by performing comparative analyzes between various construction innovative solutions (lean construction, Six Sigma, and IPD) to identify the similarities and the differences in their adoption approaches. Then, BIM barriers are analyzed based on the sociotechnical theory which categorizes the influencing factors along four dimensions: people, tasks, structures, and organization. The results highlight substantial resemblance among the adoption approaches of various innovative concepts mainly in two aspects, people and tasks, pointing out that spreading the knowledge of a new methodology, examining the participants' attitude and mindset towards it, and deciding on the adoption process based on the financial recourses and the human skills necessary for the adoption of any concept. Additionally, the study shows that BIM barriers are established mainly by the social behavior of practitioners and the social measures of the construction sector, indicating that social variables (people and structure) are responsible for the largest portion of implementation failures due to the cruciality of human decisions. Moreover, the study clearly demonstrates that the impact dimension of a limitation is not identical to its root cause dimension. [ABSTRACT FROM AUTHOR]

Despite the recent efforts in characterizing and investigating the dynamic properties of tire-derived aggregates (TDA) and its use in civil engineering applications, the size of TDA used in most of the previous work was significantly smaller than the TDA size range mentioned in ASTM D6270 standards. There are two types of TDA, Type A and Type B, in which the maximum aggregate size of Types A and B are 200 and 450 mm, respectively. Thus, the availability of experimental data and shear modulus reduction curves for the dynamic behavior of TDA of larger sizes are deemed necessary for practical engineers to assess and investigate the behavior of such material under dynamic loads. This paper provides the results of large-scale undrained cyclic triaxial tests performed on Type A TDA at large strain amplitudes. The tests were performed under confining pressures ranging from 25 to 200 kPa and shear strain levels ranging from 0.1% to 10%. Furthermore, each test consisted of successive stages in which the number of cycles and axial strain levels varied. The shear modulus of Type A TDA has a range of 245–1,796 kPa, with a decreasing trend with increasing shear strain amplitudes. Furthermore, the dampening ratios were found to range from 11% to 23.5%. Finally, the shear modulus reduction curves were obtained through curve fitting techniques and nonlinear regression. [ABSTRACT FROM AUTHOR]

Tampa Bay, FL, is a large, ecologically rich estuary that hosts one of the largest commercial ports in Florida. Automatic identification system (AIS) records from 2015 to 2017 were used to determine the number, size, speed, type, and transits of vessels in Tampa Bay. The AIS vessel types were grouped into 10 general classes based on function. The cargo and tanker classes had the highest number of unique vessels transiting the estuary. The tug class had the highest number of individual transits, followed by cargo class. The most common vessel lengths were 165–200 m. Typical drafts were 9–11 m, and ship speeds were almost all <10 m/s. Froude numbers calculated from these data indicated that ships were generally underway in displacement mode. Overall, <0.1% of the AIS records reported speeds >10 m/s. These were identified as smaller passenger and recreational vessels operating in planing mode. The AIS navigational status and speed were often inconsistent, therefore, the combination of speed and duration was used to define individual transits. The average tidal dependency (TD) parameter for all vessels transiting into the bay was −0.02, and 0.10 for combined cargo and tanker vessels. Proper evaluation of the TD required inclusion of the phase lag between the entrance position and the tide gauge. [ABSTRACT FROM AUTHOR]

Identification of virus sources is one of the most important activities to control the spread of epidemics. Virus sources can be identified using an inverse optimization model. The inverse optimization model minimizes the error between simulated and observed concentrations at observation locations of the aquifer. The observed concentration can be obtained from field observation of contaminants. The simulated concentration can be obtained through the flow and virus transport simulation models. As such, the flow and transport simulation models need to be incorporated into the optimization model. As a result, the complexity of the problem is related to the dimension of the simulation models. For reducing the computational burden, generally, one- or two-dimensional simulation model is considered in finding the virus sources. However, to mimic the real world situation, one has to use the three-dimensional (3D) virus transport processes. Furthermore, in earlier studies, the number and the source locations are considered to be known. Thus, this study deals with the identification of a virus source in an unconfined 3D groundwater aquifer considering source location and number as variables. The methodology proposed allows running the models in an external environment to generate the simulated concentrations with arbitrary sources. The optimization model is solved using the pattern search algorithm. Two hypothetical problems have been considered to show the potential of the algorithm. The promising results show that virus sources in an aquifer can be identified even when the location and number of sources are not known. [ABSTRACT FROM AUTHOR]

Field studies, modeling, and the design of two major outfalls to discharge domestic wastewater from Buenos Aires, Argentina, into the Río de la Plata are described. Extensive data were gathered from current profilers, Lagrangian drifters, meteorological stations, and water column profiling. The river is essentially freshwater and is the main water source for the city; it is tidally dominated, shallow, and wellmixed vertically. The data were used to develop a two-dimensional hydrodynamic model of the river that closely simulated its major features. The wastewater disposal strategy and special design and modeling considerations of the outfalls and diffusers are discussed. The tidal currents will recirculate the wastewater back and forth over the diffuser several times before it is flushed away by the mean river flow. Because of the shallow water and low flushing currents, it is not possible to achieve the high near-field dilutions typical of deep-water marine outfalls, and other design constraints include the proximity to water intakes. Lagrangian particle-tracking modeling approaches were used to predict the fate and transport of the effluent and its dilution. The models reproduce near-field mixing at moderate to high current speeds and also reentrainment due to the reversing tide without the need for special model coupling. However, dilutions at low current speeds were corrected to account for the jet momentum and reentrainment. The near-field jet modeling to determine the riser and port designs is discussed. Bacterial impacts decreased rapidly with distance from the diffuser and no impacts on the shoreline or water intakes were predicted. The effects of sudestadas were also modeled and it was concluded that they will not significantly affect water quality for the proposed outfalls. [ABSTRACT FROM AUTHOR]

In this paper, the performance and structural changes in cement-treated soils under influence of freeze/thaw (f/t) exposure are investigated. Specimens from plastic and compacted soil-cement mix designs were exposed to different f/t scenarios to study the influence of f/t dimensionality (i.e., one-dimensional versus three-dimensional exposure) and specimens’ age at the time of f/t exposure on changes in their performance. Changes in hydraulic conductivity, unconfined compressive strength, and longitudinal resonant frequency of the specimens were studied under each exposure scenario. An examination of the microstructure of the f/t exposed and control specimens using transmitted light optical microscopy was also performed to evaluate how the soil-cement matrix was disrupted after exposure to f/t cycling. Observations showed increases in water content of the mix design (when wet of optimum water content), as well as increased specimen age at the time of exposure may increase f/t susceptibility. On the other hand, comparison of the performance of the specimens exposed to 1D and 3D f/t exposure did not show any significant variation. Microstructural analysis of petrographic thin section samples from control and f/t exposed specimens showed that while optical microscopy can detect matrix disintegration for highly damaged specimens, it is not able to identify structural degradation at early stages of damage development. [ABSTRACT FROM AUTHOR]

The aim of this paper is to evaluate water resources use efficiency (WRUE), which focuses on the entire water consumption process by utilizing data envelopment analysis (DEA) and the Malmquist index (MI). A comprehensive analysis of WRUE both on the spatial and temporal scale has been conducted. For the spatial scale, the difference of WRUEs among cities is presented, and the negative factors by analyzing and decomposing relative water resources use efficiency (RWRUE) are examined. Similarly, the dynamic changes of WRUE over time is presented to analyze the temporal scale. Moreover, a real-world case study in Guansu Province, China, from 2003 to 2013 is employed to evaluate the performance of the proposed WRUE analysis. Results show that the decision makers can determine the comprehensive and accurate WRUE and negative factors of WRUE in Gansu. Furthermore, the results provide alternative recommendations to decision makers to plan for efficient use of water resources in different cities. [ABSTRACT FROM AUTHOR]

To demonstrate the feasibility of photocatalysis for the removal of polycyclic aromatic hydrocarbons (PAHs) from offshoreproduced water (OPW), the effects of water matrix were studied by comparing the performance of TiO2-induced photocatalysis in distilled water and OPW media. The effects of salinity, insoluble particulate matter, and organic composition were evaluated. The results showed the strong improvements with the addition of catalysts but the enhancement of photocatalysis was restricted by OPW media. The photocatalytic degradation of PAHs with high molecular weights was more sensitive to the variations of salinity and insoluble matter due to their lower solubility. The overall degradation of PAHs was strongly restricted by the organic composition in OPW particularly the aromatic compounds. The aromatic compounds played an important role as ultraviolet-photon absorbents and competed with the photodegradation of PAHs. Because of their abundance in OPW, these species had the most significant effect on the photocatalytic degradation of PAHs. [ABSTRACT FROM AUTHOR]

A closed-form, multiple-scales, analytic approximation of a Kelvin-Voight viscoelastic model is developed to describe water hammer pressure wave attenuation in polymer pipe. The analytical results show that the evolution of water hammer for the single-pipe experiment considered in this paper is described by the Kelvin-Voight model as a weak strain-rate feedback occurring over three timescales. The wave transit and frictional timescales are augmented by a third intermediate timescale governed by the weakness of the strain-rate feedback. The scaling analysis also shows that, for weak strain-rate feedback, it is possible to use an optimization approach to estimate the scale of Kelvin-Voight parameters without experimental data. The optimal choice for weakness of the strain-rate feedback also determines the extent to which a weak strain-rate feedback description may be appropriate to describe an experimental design. [ABSTRACT FROM AUTHOR]

Advances in fiber-reinforced polymer (FRP) technology have led to the introduction of new basalt-fiber-reinforced-polymer (BFRP) bars. This paper presents a research project investigating the behavior of edge-restrained concrete bridge-deck slabs reinforced with BFRP bars. The tests included six full-scale edge-restrained concrete deck slabs simulating a slab-on-girder bridge deck commonly used in North America and one full-scale unrestrained concrete deck slab. The deck slabs measured 3,000 mm long x 2,500 mm wide x 200 mm thick. The test parameters investigated were (1) reinforcement type (BFRP and steel); (2) BFRP bar size (12 and 16 mm); (3) reinforcement ratio in each direction (0.4-1.2%); and (4) edge-restraining [restrained or unrestrained (free)].The slabs were tested up to failure over a center-to-center span of 2,000 mm under a single concentrated load acting on the center of each slab over a contact area of 600 x 250 mm to simulate the footprint of a sustained truck wheel load (87.5-kN CL-625 truck) as specified in Canadian standards. The observed mode of failure for the edge-restrained deck slabs was punching-shear, with carrying capacities exceeding the design factored load specified by Canadian standards. [ABSTRACT FROM AUTHOR]

Water scarcity and aquatic environment deterioration have become increasingly serious problems in Urumqi, China. To alleviate the conflicts arising from competitive water users and retard the environment degradation, an optimization model was developed for regional water resources management under considering the dual total amount of water quantity and pollutant emissions control. Water allocation schemes and guarantee rates that combine diverse water sources and economic activities were obtained through the solutions of the proposed model. The interactions among water allocation schemes, various activities benefits, and pollutant emissions were analyzed synchronously. Policies for industrial structure adjustment and pollutants emission reduction were acquired through the analysis of the results. The modeling results can be valuable for water resources planning and justification of the existing industrial structure. [ABSTRACT FROM AUTHOR]

This paper studies the flexural performance of sandwich panels composed of a soft polyurethane foam core and glass-fiber-reinforced polymer (GFRP) skins. A robust numerical model is developed to predict the full load-deflection and strain responses of the panel. It is based on equilibrium and strain compatibility and accounts for the excessive shear deformation and material nonlinearity of the core. It also accounts for geometric nonlinearity in the form of localized deflection of the loaded skin using the principals of beam-on-elastic foundation and the change in core thickness due to its softness. The model incorporates various failure criteria, namely core shear failure, core flexural tension or compression failure, compression skin crushing or wrinkling, or tensile rupture of skin. The model has the advantage of being able to isolate quantitatively the individual contributions of flexure, shear, and localized skin deformations, to overall deflection. A parametric study is performed to examine the effects of core density and skin thickness on panel behavior. It is shown that as the core density increases from 32 to 192 kg/m³, the contribution of shear to overall deflection reduces from about 90 to 10%. It also appears that the optimal core density of the sandwich panels is within 96 to 128 kg/m³, which represents the lowest density necessary to achieve the highest ultimate strength and stiffness. [ABSTRACT FROM AUTHOR]

Heger pressure distributions are considered a fundamental tool in the design of RC culverts, according to the direct-design method. However, some factors known to affect soil-structure interaction are neglected when using Heger pressure distributions. These factors include the effect of the trench geometry, the relative stiffness of the existing soil to the backfill, and the burial depth of the structure. This paper presents a detailed finite-element analysis parametric study that investigates the accuracy and applicability of Heger pressure distributions for culverts in partial trench installations when the aforementioned factors are considered. [ABSTRACT FROM AUTHOR]

Exposure to lead in drinking water poses a risk for various adverse health effects, and significant efforts have been made to monitor and eliminate lead exposure in drinking water. This study focused on the localization of lead exposure from 71 drinking water fountains in nonresidential buildings in order to determine the source of elevated lead and understand the effects of fountains associated with lead concentration in drinking water. Drinking water fountains containing lead-lined cooling tanks and brass fittings were found to release lead concentrations in excess of 10 µg=L, and fountains with low or infrequent usage and those with cooling tanks produced the highest concentrations (in excess of 20 µg=L) of lead. One particular fountain model found at several locations throughout the institution was associated with some of the highest lead concentrations measured throughout the study. This fountain was recalled in the United States, but not in Canada. This article adds to existing research demonstrating that drinking water fountains are a potentially significant and underappreciated source of lead exposure in nonresidential buildings. [ABSTRACT FROM AUTHOR]

Phosphate, a key nutrient for bacterial growth, is also a key component of many corrosion-control programs to manage lead and copper corrosion in premise plumbing. Bench-scale stagnant water galvanic macrocells with lead and copper components were fed with drinking water containing three levels of zinc orthophosphate [0 (control), 1, and 3 mg l-1-PO4]. Suspended polycarbonate coupons, representing benign downstream fixtures, were placed in the macrocells, thus enabling biofilm formation on this material. Community profiling using denaturing gradient gel electrophoresis (16S rDNA PCR-DGGE) revealed that phosphate dose (primarily) and metal type (to a lesser extent) influenced biofilm community diversity. Generally, community diversity increased with increasing heterotrophic plate counts that in turn rose in response to elevated phosphate. Partial 16s rDNA sequences obtained from DGGE gel bands identified the dominant bacterial taxa as the phyla Verrumicrobia, Firmicutes, Bacteroidetes, and α-Proteobacteria. The increase in size and diversity of biofilm communities as a result of phosphate treatment further highlights the challenges of a phosphate corrosion-control program. [ABSTRACT FROM AUTHOR]

Single-stage and two-stage treatment processes using ferric sulphate (Fe2(SO4)3) coagulation, lime precipitation, ballasted flocculation, and sedimentation were compared for the removal of high concentrations (i.e., 60 mg/L) of arsenic in a synthetic mine water (SMW). Single-stage treatment was found to reduce arsenic to 0.39 ± 0.04 mg/L in As(V) SMW and 0.78 ± 0.07 mg/L in As(III) SMW using either preoxidation with KMnO4 or higher pH and coagulant dose compared to As(V) (i.e., 9.0 to 9.5 versus 5.5 to 6.0 and 151 versus 76 mg Fe/L), above a proposed national discharge guideline of 0.10 mg As/L. The two-stage treatment process was able to reduce total arsenic concentrations to 0.004 ± 0.002 mg/L for As(V) SMW using coagulation and ballasted flocculation alone in Stage 2, 0.010 ± 0.008 mg/L for As(III) with oxidation upstream of the second coagulation stage, and 0.037 ± 0.006 mg/L for As(III) with pH adjustment downstream of it. The two-stage process was shown to achieve optimum performance at colder operating temperatures (i.e., 3 versus 23°C). [ABSTRACT FROM AUTHOR]

This study was designed to identify the effects of variable concentrations of chloride on microbial regrowth, disinfection efficacy, and metal release in drinking water distribution systems. Annular reactors (ARs) containing cast iron or polycarbonate coupons were operated in this study to simulate distribution systems. Experiments were conducted with test water containing chloride concentrations of 10, 75, and 250 mg/L. Chlorine disinfection was applied to achieve 0.2 and 1.0 mg/L free chlorine residuals. Results showed that the ARs operated with elevated chloride concentrations were not significantly different from the ARs operated with low chloride concentrations in terms of microbial regrowth. However, there was a significant increase in iron concentrations after chlorination in the high chloride ARs. Further, more iron release was observed in these ARs at 1.0 mg/L compared to 0.2 mg/L chlorine residual. Higher chlorine doses were required to achieve goal residuals for those ARs with higher chloride concentration in cast iron systems. However, in polycarbonate systems, similar doses of chlorine were required to achieve the target free chlorine residual in both low-chloride and high-chloride ARs. [ABSTRACT FROM AUTHOR]

The objective of this research is to evaluate the reliability of bridge decks that use nonconventional materials or structural forms such as externally restrained deck systems where the available deterioration models developed for conventional systems are not applicable. The method developed here adopts the reliability theory and establishes a deterioration model for such bridge decks based on their failure mechanisms. The externally restrained deck is an innovative structural system introduced about a decade ago to the construction industry and provides corrosion-free replacement for conventional reinforced concrete decks. Because there is no established deterioration model available for these innovative systems, it is difficult to predict the reliability of such bridge decks at different instances of time. The developed method has been applied to an innovative structure with an externally restrained deck system, namely the Crowchild Trail Bridge, in Calgary, Canada, as a case study. A finite-element model of the bridge has been developed and calibrated with experimental results giving static deflection, vibration characteristics, load distribution, and crack patterns. The system reliability has been determined at different times using the proposed method. The results show that the design is quite conservative and there is a very low probability of failure for such a system during its design life. [ABSTRACT FROM AUTHOR]

In this paper the impact resonance (IR) test method is used as a nondestructive tool to examine the curing progression, freeze/thaw (f/t) resistance, and healing potential of cement-stabilized soils. Resonant frequency (RF) measurements on specimens moist cured for up to 241 days indicate that the main portion of the hydration process is completed after about 60 days. Results of RF measurements on immature (i.e., cured for 16 days) and mature (i.e., cured for over 110 days) specimens exposed to 12 cycles of f/t indicate that the initial f/t exposure had a significant effect on the degradation of the structure. After the initial f/t cycle, some specimens exhibited continued reductions in RF values to as low as 10% of the initial measurements, while several specimens showed signs of recovery leading to minor increases in the RF values. Changes in RF values are compared with the hydraulic conductivity changes measured on the same specimens reported in a previous publication by the authors. Based on the results, a prescreening scheme is proposed that can significantly reduce the time required for f/t studies of cement-stabilized soils. Also, RF measurements after 120 days of a post-exposure healing period show a significant potential for recovery in RF values for f/t exposed specimens. However, the recoveries in RF values are not proportional to the hydraulic conductivity recovery of the specimens. [ABSTRACT FROM AUTHOR]

A field trial involving the surface detonation of the equivalent of 5,000 kg of trinitrotoluene (TNT) was carried out in Woomera, South Australia. The overpressures, impulses, and related information obtained from this trial were analyzed and compared against available predictive procedures and previously published data sets. A predictive procedure that is adopted in the widely used Unified Facilities Criteria (UFC) 3-340-02 is based on equations that are established through a small data set, in which issues such as afterburning, increased pressure as a result of the chemical reaction zone, and blast wave asymmetricality were not addressed. The data set contains data from mid and far-field explosions, in which the pressure data in the data set were not directly measured, but were inferred through the arrival-time data. This leads to a significant level of uncertainty in the UFC 3-340-02 procedure, especially for closed-in explosions. Differences between the field measurements and the predictions made when using the blast-parameter charts in UFC 3-340-02 and a computational fluid dynamics code are identified and analyzed in this paper. The findings of the analysis imply that the current predictive approach will neither capture the variabilities of blast parameters in an actual event, as it does not account for the shape of the charge, nor capture the uncertain behavior of the blast wave at a close standoff distance. This may lead to an overly conservative prediction of the impulse or an underestimation of the peak overpressure. The findings of the analysis show that in an uncontrolled blast event, the reliability of the empirical charts provided in the UFC 3-340-02 is questionable. [ABSTRACT FROM AUTHOR]

To evaluate the economic feasibility of energy efficiency or renewable energy upgrades, a variety of tests are used such as payback period, cost-benefit ratio, and return on investment. All of these tests require an estimate of the capital cost of the upgrade. However, it is not always possible to reliably estimate the capital cost of a potential energy upgrade. To deal with such situations, an alternative approach is proposed that involves the calculation of the tolerable capital cost (TCC) of the upgrade. The use of the TCC approach to evaluate economic feasibility is demonstrated with a case study involving photovoltaic panel installations in Canadian houses. [ABSTRACT FROM AUTHOR]

The preparation and development of sludge management plans for waste stabilization ponds in Nunavut communities require the selection of processing options that are both appropriate for each community and minimize the total regional operating cost. Considering Nunavut's unique regional constraints, five feasible sludge processing treatment trains were identified. A linear programming model was developed to identify the optimal selection of treatment technologies for 13 Nunavut communities that would minimize the total cost of sludge processing over a period of 40 years. In this study, preliminary cost estimates and literaturebased sludge accumulation rates were used as inputs for the linear program, which is intended to be adaptable as more precise costs and accumulation rates are determined through initial project development and field study. [ABSTRACT FROM AUTHOR]

Cement-based solidification/stabilization (s=s) is a remediation technology that has been widely used for treatment of a range of contaminants. Currently, there is limited published data on changes in hydraulic performance of cementtreated materials subjected to cycles of freezing/thawing (f=t). Fourteen sets of tests were performed to examine the influence of factors such as number of f=t cycles, freezing temperature, curing time, and mix design on changes in hydraulic conductivity and unconfined compressive strength (UCS) of cement-treated silty sand. Results showed an increase of up to three orders of magnitude in hydraulic conductivity as well as decreases in UCS values after exposure to 4 and 12 f=t cycles. Analysis of variance (ANOVA) performed on the results of a factorial experiment considering the effect of freezing temperature, curing time, and number of f=t cycles showed that all of these factors are significant in affecting the measured changes in the hydraulic conductivity and UCS values. Monitoring of damage using the impact resonance method showed that changes in the resonant frequency of specimens were consistent with changes in hydraulic conductivity and UCS after f=t exposure and also allowed monitoring of damage for intermediate cycles with minimal effort. [ABSTRACT FROM AUTHOR]

Construction of new highway embankments in urban areas often requires building over existing underground utilities and lifelines. Embankments constructed over such utilities often induce substantial additional earth pressures causing overstressing and/or unacceptable deformations of the buried pipes, resulting in interruption of service for both the utility and highway. There are several techniques that can be used to mitigate this problem. Geogrid-reinforced bridge platforms are one of the newer techniques to deal with this problem. In order to gain a better understanding of the earth pressure reduction that may be achieved by geogrid bridging, the Ontario Ministry of Transportation (MTO) constructed an instrumented full-scale test embankment over a geogrid-reinforced bridged trench. In this paper, the results of this full-scale test along with a numerical study to evaluate the stress reductions achieved by the use of geogrid bridging platform installation are reported. In addition, results of a parametric study to investigate the soil structure interaction of the proposed stress reduction system and its effectiveness on the reduction of the deformations, moments, and normal forces of a buried culvert are presented. [ABSTRACT FROM AUTHOR]

A multiple scales asymptotic analysis is developed to describe the attenuation of a water hammer pressure wave initiated by a time-varying valve closure. The analytical results expose a simple rule-of-thumb relationship between water hammer pressure wave attenuation and the periodic average of the absolute flow velocity that is predicted by a quasi-steady friction model. The effect of flow reversals on the pressure wave attenuation is examined through comparison with a similar method applied to the water hammer generated during flow establishment, wherein flow reversals do not occur and there is a nonzero net flow. Although the analytical description is based on the assumption that the water hammer is generated by a sudden valve closure, its practical usefulness is extended by using the numerical solution as a guide to demonstrate its validity for a range of valve closure durations. A qualitative upper limit on closure times to which the analytic results may be applied is also found. All results are numerically verified using the method of characteristics. [ABSTRACT FROM AUTHOR]

A matched asymptotic expansion analysis is used to determine the dependence of shear stress boundary layer thickness on adhesive properties in unbalanced single-lap joints. A uniformly accurate expansion of shear stress, in a small and positive dimensionless parameter , is shown to contain a pair of adhesive edge boundary layers and an outer zone where the stress is slowly varying between the two layers. An overlap constraint is also found, and if it can be satisfied for , then there is sufficient overlap and a single boundary layer of width the order of at either adhesive end. The analytic results are presented in a generic format allowing their application and/or extension to similar problems. All results are numerically verified using a finite difference approximation. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess lead release in a pipe rig system that was disinfected with either chloramines or free chlorine. The study was carried out using pipe loops and copper pipe rigs that had lead solder, which provided the only source of lead. The water quality of the treated water had a low alkalinity ( as ), neutral pH, and low hardness ( as ). However, the study used a corrosion control program that consisted of dosing with 0.8-mg of zinc orthophosphate and controlling the pH to 7.3, that was consistent with the corrosion-control program operated in the host water treatment plant. Key findings from the study confirmed that chloramines would result in lead release under the current corrosion-control program, whereas free chlorine was not as compromising. Lead concentrations were approximately an order of magnitude lower in the free chlorine system than the chloramine systems. In this study, chloramines with a target residual concentration of released and following stagnation times of 24 h and 30 min, respectively. Furthermore, chloramines with a target residual concentration of resulted in a lead release of and following a stagnation time of 24 h and 30 min, respectively. By comparison, the pipe rigs that were dosed with a free chlorine target residual concentration of had lead concentrations of and for the 24-h and 30-min stagnation times. This project demonstrates that care needs to be taken when evaluating secondary disinfectants, particularly for those water systems having a low dissolved inorganic carbon concentration. [ABSTRACT FROM AUTHOR]

Liner systems are increasingly being used to protect the environment from contaminated waste. At the same time, society is increasingly insisting on estimates of the probability that these liner systems will fail to achieve their design objectives, one of which is to limit hydraulic flow from the contaminated region to acceptably small levels. This paper presents a methodology to estimate the probability of excessive hydraulic flow, considering the spatial variability of the soil composing the liner (its mean, variance, and correlation length) as well as the liner thickness. Semiempirical equations predicting the mean and variance of the effective hydraulic conductivity of the liner, based on theory and calibrated by random finite-element method simulations, are presented and used to investigate the probability that a liner exceeds regulatory hydraulic flow requirements. The proposed methodology is illustrated by an example. [ABSTRACT FROM AUTHOR]

A purely numerical parametric study of 24 flow-through rockfill dam geometries was conducted. The nonlinear nature of the p-LaPlacian-like partial differential equation was dealt with using a finite-difference scheme that directly incorporated the exponent of a power law that replaced Darcy's law. Convergence, use of specialty nodes, nodal density, and boundary condition effects were quantitatively investigated. The flow-field angle of the toe was found to be a useful starting point in studying the potential for unraveling failure. Factors of safety (FS) against this type of failure are then presented for a range of downstream slopes, thus showing which combinations of slope and particle diameter are unsafe. It is shown that the FS tends to drop below unity under the seepage face primarily because of the strength of the exit gradient near the toe of the structure and secondarily because of the overflow velocity. It is hoped that the techniques and results presented will facilitate the design and assessment of flow-through rockfill structures. [ABSTRACT FROM AUTHOR]

To assess the potential for unraveling failure of flow-through rockfill dams, a systematic study of three aspects of the hydraulic design of these structures was conducted. First, the gradient that is most useful in independently computing the height of the point of first flow emergence was established. The proposed method is based on the idea of the angle of the emergent flow field within the toe of the structure. Secondly, as a result, this study presents a method for independently computing the variation in hydraulic head within the vertical that allows the toe of the structure (i.e., downstream from the vertical associated with first flow emergence) to be isolated. This is based in part on a separate parametric study of 24 numerically simulated flow-through rockfill dams. Thirdly, the gradient that allows for the independent estimation of the default tailwater depth is presented and verified, with the help of laboratory results. The hope is that these three computational tools will facilitate the design and assessment of flow-through rockfill structures, as a particular class of pseudohydraulic structure. [ABSTRACT FROM AUTHOR]

On-site treatment of residential wastewater is important for rural and remote regions where centralized wastewater treatment may not be feasible. Sand filtration is a proven method for secondary treatment of septic tank effluent (STE) and can be an economical option where soil conditions do not favor the installation of a typical disposal field. This study investigates the hydraulics and treatment performance of eight lateral flow sand filters (LFSFs) receiving domestic STE at the Bio-Environmental Engineering Centre (BEEC) in Truro, Nova Scotia, Canada. The main objectives of this study were to evaluate the long-term treatment performance associated with the LFSFs and to investigate the effects of filter length and wastewater loading on performance. Previous research conducted at the BEEC indicated that current technical guidelines used in Nova Scotia for the design of LFSFs may be conservative and that the design of these systems could be optimized. The hydraulics and treatment performance associated with: (1) two shortened length filters (5.5 m versus 8 m standard length), and (2) six standard length filters receiving double the recommended hydraulic loading rate were evaluated. Results were compared to the previously documented performance of standard length filters operating at the recommended loading rate. Filters included fine (d10=0.15 mm), medium (d10=0.17 mm), and coarse (d10=0.30 mm)-grained sands with hydraulic conductivities ranging from 1.5×10-4 to 1×10-3 m s-1 at slopes of 5 and 30%. Hydraulic residence times (HRT) were determined for each filter several times during the study period using a conservative tracer. Average removal efficiencies ranged from 82.4 to 96.9% for total suspended solids (TSS), 96.7 to 98.4% for five-day biochemical oxygen demand (BOD5), 4.3 to 5.2 log reduction for Escherichia coli (E. coli), 43.7 to 93.4% for total phosphorous (TP), and 40.9 to 57.2% for total nitrogen (TN). Water quality analysis indicated that both the shortened filters and the filters receiving higher hydraulic loading rates provided a similar level of treatment for most parameters. This suggests that sand filtration is not only a physical treatment process but can be attributed mainly to Fbiological degradation of contaminants that occurs within the biomat. Filter length and loading rate adjustments did not appear to affect the HRT of the filters, suggesting that the biomat also plays an important role in the hydraulic functioning of the filters. Based on performance and tracer study results, LFSFs appear to maintain their hydraulic function and provide adequate contaminant removal at linear loading rates ranging from 66 L m-1 d-1 to 132 L m-1 d-1 of domestic STE. Long-term performance monitoring must continue in order to adequately assess the effects of filter length and wastewater loading on treatment performance and to further evaluate current design guidelines. [ABSTRACT FROM AUTHOR]

The use of externally post-tensioned fiber-reinforced concrete decks in highway bridge structures is seen as a viable option in the move toward the design and construction of high-performance structures. However, with the thin unreinforced deck slabs that may result, punching shear is a potential concern. An experimental program is described in which the punching shear behavior of externally prestressed slabs is investigated, both with plain and fiber-reinforced concrete specimens. Results indicate that significant improvements in strength, ductility, energy absorption and nonbrittleness of failure can be achieved with fiber reinforcement. Nonlinear finite-element analysis procedures are used to model the specimens, and reasonably accurate simulations of behavior are obtained. Design code procedures are found to be unconservative in estimating the punching shear strength of these elements, whereas a commonly used analytical model is found to be overly conservative. [ABSTRACT FROM AUTHOR]