Search

Construction models received by owners typically include the details of components required for construction activities; yet at the same time, they might not be in the right geometric representation for facilities management (FM) tasks. There is a need to customize BIMs for each FM task and eliminate unnecessary data in models for that task. The objective of this work is to identify information items that should be included in BIMs to support specific FM tasks and the level of geometric details of components to be represented in BIMs. The research focuses on supporting four major FM tasks as corrective and preventive maintenance management, asset management on HVAC systems, and space management tasks. This paper also provides a system architecture to enable reducing content of BIMs for FM tasks. Contributions will help practitioners to use facility data from a life cycle perspective through BIM. [ABSTRACT FROM AUTHOR]

Collaboration is essential for the success of construction projects. However, the concept of collaboration is unclear, and the term is often related to different meanings. Construction research defines collaboration in different ways, having been influenced by other research fields (e.g., social sciences and philosophy). This paper discusses existing definitions of collaboration and how they relate to three perspectives on the nature of collaborative interactions, linked to organisational metaphors. The research was developed through a literature review, including the conceptual analysis of existing definitions of collaboration. The discussion proposes that metaphors not only describe collaboration ontologically, but also establish different appreciative systems by which individuals conceive and evaluate their collaborative performance. The aim of this discussion is to address the lack of consistency in defining collaboration in construction, embracing the coexistence of interpretations. This can help researchers and practitioners understand how to overcome misunderstandings and explore initiatives to improve collaboration. [ABSTRACT FROM AUTHOR]

The aim of this research was to expand the current understanding of social aspects related to the successful adoption of Building Information Modeling (BIM) to support mechanical–electrical–plumbing (MEP) coordination and identify contributions of the Last Planner System (LPS) to tackle these aspects. The paper presents an action-research project carried out by a mechanical contractor. This study revealed that successful BIM-enabled MEP coordination depends not only on efforts to coordinate the model itself, but also on how effectively it is used during the installation phase. Social elements that influenced the effectiveness of BIM-enabled MEP coordination were classified in three categories: clarity of roles and responsibilities, individual vs. collective project leadership, and the existence of agreed-upon processes to follow. In such context, the LPS contributed to strengthening teamwork, providing a structure for increased communication and accountability, and helping the project team to focus on problem-solving. Consequently, the model was used more effectively, reducing rework and improving field productivity. [ABSTRACT FROM AUTHOR]

Three highway bridges in the Canadian province of Manitoba are being monitored continuously not only for their long-term performance but also for bridge weighing-in-motion (BWIM). Data collected for the BWIM study has led to some observations that have far-reaching consequences about the design and evaluation loads for highway bridges. This paper presents the well-known concept of equivalent base length, Bm, as a useful tool for comparing trucks with different axle weight and spacing configurations as they influence load effects in all bridges. It is discussed that the statistics of gross vehicle weights (GVWs), W, collected over a one-month period is not significantly different from that for the GVW data collected over a longer period. A rational method concludes that the value of W for the CL-W Truck, the design live load specified by the Canadian Highway Bridge Design Code, is 555 kN for Manitoba. The observed truck data in Manitoba presented on the W–Bm space is found to be similar to that collected in the Canadian province of Ontario more than four decades ago. It was also found that the multi-presence factors, accounting for the presence of side-by-side trucks in two-lane bridges, specified in North American bridge design and evaluation codes are somewhat conservative. [ABSTRACT FROM AUTHOR]

In this paper, a new matrix framework has been developed for the simulation of flow and pressure in porous media. In this framework, the pressure gradient formulation in Darcy's law is considered as the head-loss equation in pipe network modeling. Then, an artificial pipe network has been constructed to find the pressure head profile in porous media. Two explicit and implicit formulations have been advanced for linear and nonlinear analysis, which the latter is an implementation of the Newton–Raphson algorithm. Both formulations iteratively solve a linear system of equations for calculating the nodal heads and apply a matrix multiplication for updating the flow vector. While the explicit method needs few iterations, the implicit method requires at least 20 iterations to converge with acceptable accuracy. For testing these formulations, four different types of network configurations were tested. The analysis of three laboratory tests showed that the application of the implicit method provides reliable and accurate results. [ABSTRACT FROM AUTHOR]

This paper evaluated mixed mode I/II fracture toughness of fiber-reinforced concrete using cracked semi-circular bend (SCB) specimens subjected to three-point bending test. Additionally, a comparison was made between the experimental results and the estimations made by different theoretical criteria. Natural and synthetic fibers at various concentrations were used in this study. After producing cracks in SCB specimens at different inclination angles to induce different mixed mode loading conditions (from pure mode I to II), the fracture toughness of SCB specimens was determined. Furthermore, the compressive, splitting tensile, and flexural strength of natural and synthetic fiber-reinforced concrete were measured after 7 and 28 days of curing. While there is an increase in the aforementioned strengths with fiber content increase, 0.3% was found to be the optimum percentage regarding fracture toughness for both fibers. Also, the comparison between the experimental and theoretical results showed that generalized maximum tangential stress criterion estimated the experimental data satisfactorily. [ABSTRACT FROM AUTHOR]

Fast-tracking is an important process to speed the delivery of construction projects. To support optimum fast-tracking decisions, this paper introduces a generic schedule optimization framework that integrates four schedule acceleration dimensions: linear activity crashing; discrete activity modes of execution; alternative network paths; and flexible activity overlapping. Because excessive schedule compression can lead to space congestion and overstressed workers, the optimization formulation uses specific variables and constraints to prevent simultaneous use of overlapping and crashing at the same activity segment. To handle complex projects with a variety of milestones, resource limits, and constraints, the framework has been implemented using the constraint programming (CP) technique. Comparison with a literature case study and further experimentation demonstrated the flexibility and superior performance of the proposed model. The novelty of the model stems from its integrated multi-dimensional formulation, its CP engine, and its ability to provide alternative fast-track schedules to strictly constrained projects without overstressing the construction workers. [ABSTRACT FROM AUTHOR]

Commercial floating car data (FCD) is being increasingly used as a traffic data source due to its lower cost despite concerns about its reliability. This paper focuses on the evaluation of FCD speed quality as a surrogate measure for arterial speed from different aspects. First, FCD speed is compared to video-based traffic data, collected from a specific urban road segment and assumed as ground truth in (a) descriptive evaluations, (b) speed estimation, and (c) level of service estimation. Regression analysis carried out to derive transformation function between two datasets showed a nonlinear relation with a high correlation coefficient of 0.82. Working with data along an urban corridor of 3.6 km also showed that despite some outliers, FCD was capable of detecting peak-hour queue formations as well as incident related ones. Use of transformation function on FCD speeds helped to increase its potential in urban traffic monitoring. [ABSTRACT FROM AUTHOR]

Wind-driven rain is one of the most important moisture sources that may lead to moisture damage risks of building envelopes, particularly when the rainwater unintentionally infiltrates into the envelope assembly through defects of the wall components. This paper proposes a stochastic modelling approach to evaluate the impact of rain infiltration on hygrothermal performance of highly insulated wood-framed walls, including an I-joist deep cavity wall, two exterior insulated walls, and a conventional 2×6 stud wall as the baseline wall. The stochastic hygrothermal models of the walls are created based on the uncertainties of material properties and rain deposition factor under different scenarios with rain infiltration deposited at different locations of the wall assembly. The stochastic simulation results show that the rainwater deposited on a water resistive barrier does not cause any moisture damage risk, but there is a significant risk when the rainwater is directly deposited on the exterior or interior surface of wood sheathing, and the interior deposition has the highest risk. [ABSTRACT FROM AUTHOR]

The issue regarding the corrosion of steel ties connecting brick veneer to a structural backing is well documented. In this paper, the predicted corrosion rate and resulting service life estimates, produced by a time-stepped service life model developed in Visual Basic for EXCEL, for metal ties embedded in mortar, are compared with the empirically determined corrosion rates and service lives of 16 zinc galvanized tie specimens taken from 13 buildings located in 6 different Canadian cities. This tie service life model, coined the "Tie Service Life Predictor", correlates the external environment of the building to the tie life. As with most corrosion models for steel embedded in concrete (or mortar), the model is broken into two distinct phases: corrosion initiation using Fick's law of diffusion and corrosion propagation. By considering the mortar surrounding the tie as the tie's atmosphere, the Tie Service Life Predictor characterizes the microenvironment (atmospheric conditions) surrounding the tie from the macroenvironment conditions. Once the atmospheric conditions were established, the ISOCORRAG atmospheric corrosion model could be used to predict the corrosion rate of zinc galvanized steel ties embedded in the mortar joints of the exterior wythe of brick veneer wall systems. The methods used to create the Tie Service Life Predictor could also be applied to service life estimation of reinforcing steel in concrete structures such as bridge decks and parking structures. [ABSTRACT FROM AUTHOR]

This paper introduces some challenges involved in assessment of service life and durability in the context of circular economy principles. It proposes a possible agenda for service life planning in a resource-constrained economy. Aspects considered include the reuse of materials and components over multiple life cycles within built assets. The interface between life cycle assessment and costing techniques, service life planning, and resilience against changing climate and performance requirements is considered. The current codes and standards, in particular within ISO 15686 series on service life, CEN 15643 on integrated sustainability assessment, and ISO 20887 on design for disassembly, are briefly described together with some implicit challenges. The contributions of CIB Task Groups are also considered, in particular CIB Task Groups 16, 39, and 115 and CIB W80 on prediction of service life of building materials methodologies. Several current EU research and development projects are briefly mentioned, in particular BAMB (Buildings as Material Banks). [ABSTRACT FROM AUTHOR]

A simplified wall assembly consisting of four material elements is considered. Optional vapor retarder and thermal resistances are located between the elements. A simplified numerical model is presented to perform probability-based risk analysis using the Monte Carlo method. The risk assessment of the wall assembly considers the interior and exterior climatic loads. The moisture transport mechanism accounted for in the analysis is diffusion. A prescribed rain load is assumed to be transferred directly to a chosen outer susceptible material element in the construction. A case study with a wooden wall structure is analyzed and the probability distribution of the time of wetness is presented for a case using 30 different climatic years, randomly varying indoor moisture excess, indoor temperature, and rain leakages. The results show that, in the case investigated in this paper, the simulations converged after 600 years. The proposed simplified model, combined with the use of Monte Carlo simulations, offers better opportunities for a systematic assessment of risk compared with the currently used simulation programs using only a design year. [ABSTRACT FROM AUTHOR]

The New Zealand Building Code (NZBC) is performance based. From a durability perspective, compliance requires a practitioner to demonstrate that materials will remain functional for the minimum periods specified. The NZBC also states that buildings must be constructed to avoid the likelihood of fungal growth or the accumulation of contaminants on linings and other building elements. Currently, there is no recognised method for practitioners to use to demonstrate that a wall system can meet this requirement for the required design life. In this paper, we consider how hygrothermal modelling, in conjunction with the VTT mould index, may be used to form the basis of such a method. In the past, there has been a discrepancy between predicted failures and field evidence, but the VTT mould index appears to correlate much better with the successful in-service history of typical New Zealand construction. [ABSTRACT FROM AUTHOR]

The increasing cost of new building construction has made repurposing existing building stock economically more viable compared with a green site new build. In addition to capital cost benefits, increasing urban densification through repurposing existing buildings is one of the solutions for enhancing the urban environment. This paper summarizes the investigative work completed to substantially improve the energy efficiency of a heritage 10 storey building in Winnipeg, Manitoba. The investigative work for the remediation involved hygrothermal modeling to rationalize the introduction of thermal insulation to the interior face of the exterior walls. Based on the modelling, an open-cell spray foam was applied to the interior face of the masonry walls. Temperature, moisture, and relative humidity sensors were placed in various locations throughout the building to monitor the exterior walls, primarily to identify if deleterious levels of moisture were accumulating in the masonry. The results were also used to compare the in-situ performance of the building with the predicted performance from the hygrothermal models. The investigation confirmed that obtaining accurate in-situ moisture readings in masonry products is significantly impacted by initial internal moisture levels, necessitating pre-test calibration. Regardless, moisture sensor data accumulated to date indicate that after six years of monitoring, deleterious levels of moisture in the masonry and plaster are not occurring in the exterior walls, which is in good agreement with hygrothermal model results for open-cell foam. The results of this investigation confirm that the implementation of hygrothermal modeling is an effective and accurate analysis tool in the long-term durability assessment of building envelopes for heritage buildings. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to identify and compare the contributing factors to bicyclist injury severity in urban and rural areas. Two mixed logit models are developed for both the urban and rural areas separately to identify factors that significantly contribute to the injury severity outcome of bicyclists resulting from bicycle–motor vehicle crashes. Data collected from 2007 to 2014 in North Carolina are utilized for the model development. The model estimation results show that factors including bicyclist age from 25 to 54, driver age under 25, vehicle speed, and divided road are found to significantly affect the injury severity outcome of bicyclists in bicycle–motor vehicle crashes in rural areas only. In contrast, factors including drivers age over 60, van, single unit truck, head-on crash, motorist overtaking bicyclist, two-way roadway, road condition, and crash time are found to have a significant impact on the injury severity of bicyclists in urban areas only. [ABSTRACT FROM AUTHOR]

The correlation between the international roughness index (IRI) and distress is inherent, as roughness is a function of both the changes in elevation of the distress-free pavement surface and the changes in elevation due to existing surface distress. In this way, a relationship between existing surface distress and IRI may be developed. However, the susceptibility of pavement to various types of surface distress is affected by many factors, including climatic conditions. A model that relates pavement surface distress to IRI for Canada needs to account for climatic conditions in different locations. This paper investigates the relationship between pavement surface distresses and IRI for different climatic conditions in Canada using historical data collected at numerous pavement test section locations sourced from the Long-Term Pavement Performance program database. Developed models were calibrated then validated and found to be statistically significant. [ABSTRACT FROM AUTHOR]

This paper presents a feasibility study on the effects of forest based ash (FBA) on the mechanical performance of concrete. Four such samples were obtained from the pulp and paper industry as the residual byproduct of their hog fuel. They were analyzed for grain size distribution, density, morphology, and oxide content. Subsequently, the ash was employed as a cement substitute (up to 20% by mass) and the resulting concrete was examined for mechanical properties. Results show that all four FBA samples were coarser than Portland cement with mean particle size around 100-1000 microns. Further, X-ray fluorescence showed that the FBA samples were predominantly composed of CaO, with significant amounts of SO3 and alkali oxides at levels that exceed maximum limits allowed for the latter by ASTM. This poses concerns on durability. Nevertheless, based on short-term compressive and tensile performance alone, this study shows that FBA could replace up to 15% by mass of cement. [ABSTRACT FROM AUTHOR]

This paper presents a summary of an experimental investigation and the derivation of a bond-slip model for reinforcing steel embedded in moderately confined concrete under monotonic and cyclic loadings. Moderately confined concrete encompasses the domain between unconfined and well-confined concrete, the limits of which are defined in the paper. The proposed constitutive law adapts and extends the well-known Eligehausen-Filippou model for well-confined concrete to moderately confined concrete. It is described by an envelope curve and degradation rules. The former is obtained through a confinement index, defined in this study as a function of the amount of confining steel and concrete, distance between confining steel and the rebar, and concrete segregation effect. It is proposed to adopt the same degradation rules used for well-confined concrete. These rules are validated through statistical tests for moderately confined concrete. They are found to predict correctly the main features of reduced envelope response under increasing cycling amplitudes but to underestimate response degradation under constant cycling limits for the subsequent cycles to the first cycle. To demonstrate the validity and limitations of the proposed model, its predictions under monotonic loading are compared with experimental results and analytical predictions from other studies. [ABSTRACT FROM AUTHOR]

Construction professionals agree that building information modelling (BIM) will revolutionize the architectural, engineering, and construction (AEC) industry and its impact will be felt by all project stakeholders including owners and facility managers. Statistics show that many owners and other stakeholders perceive BIM as a technology that can make project delivery more efficient because it allows project information to be fully integrated. In the future, owners are expected to demand the use of BIM to prevent over-budget and over-time project delivery. However, as we are preparing this contribution the level of implementation and use of BIM varies widely across the globe. This paper probes the state of BIM in Alberta from three points of view: ( i) the current understanding and implementation, ( ii) the motivations driving its use, and ( iii) the challenges hindering its implementation. The findings of this paper are extracted from individual responses to a web-based survey that was proposed to professionals in the Albertan AEC/FM industries. [ABSTRACT FROM AUTHOR]

Structural insulated panels (SIPs) are a panelized building system composed of external oriented strand board (OSB) wood sheets bonded to a lightweight boardstock or pour-in-place foam core. This paper describes an investigation on the structural behaviour of OSB-faced SIPs subject to short-term out-of-plane transverse loading. A total of 35 panels with varying types of foam core, thickness and other construction details were subjected to partially distributed uniform loading. The results showed that the ultimate shear resistance of SIPs is proportional to the mechanical properties of the core, and inversely proportional to the thickness of the core. The observed relationship between core shear stress at failure and core thickness was used to calibrate a reliability-based design expression to predict the shear strength of full-size panels based on properties obtained from small-scale foam material tests. Sandwich panel theory can accurately predict the initial stiffness of SIPs when behaviour remains in the linear range. Finally, recommendations regarding panel design and construction are made to improve the shear behaviour of SIPs. [ABSTRACT FROM AUTHOR]

This paper presents a new analytical model to predict the streamwise time-averaged velocity profile affected by the dip phenomenon in open channel flows. The novel approach of the present study is that the Finley wake law has been used instead of Coles' wake law for the outer layer. To validate the new analytical model, six high quality experiments were conducted in a hydraulically rough bed open channel flow by considering variations of aspect ratio, defined as the ratio of the width of the channel to the depth of flow, from 2 to 4. In these controlled experiments, the time-averaged velocities were measured using a Nortek Vectrino-plus acoustic Doppler velocimeter. In addition, 14 sets of available experimental data, including five field experiments conducted across the globe were also used to test the performance of the proposed model. The proposed model, the Finley-dip-modified-log-wake law (FDMLWL), was used to develop a semiempirical equation to compute the dip position as a function of the dip correction factor and the wake parameter. In addition, using the experimental data and FDMLWL, an empirical equation was developed to compute the dip correction factor for hydraulically smooth open channel flows. The comparison of the FDMLWL model with the experimental data belonging to hydraulically smooth, transition, and rough regimes has consistently indicated better representation of the velocity dip phenomenon. The FDMLWL model has also been compared with other analytical models available in the literature and the superior performance of the proposed model is further observed. Finally, based on the satisfactory validation between experimental data and FDMLWL, it is inferred that the proposed model is better suited for modeling zero velocity gradient at the boundary layer edge, as in open channel flows with dip phenomenon. [ABSTRACT FROM AUTHOR]

The purpose of this research is to enhance the performance of self-compacting concrete (SCC) to make it a more sustainable alternative to traditional concrete. SCC serves the purpose in harsh environments, therefore, requires protection against de-icing agents and harmful saline environments. This paper reports the results from a laboratory study evaluating the efficacy of two impregnants; pure-silane and water-based silane. Both materials were applied on dry and wet SCC specimens manufactured with high and medium doses of superplasticizer. When treatment is applied on dry samples, a significant reduction in chloride penetration was noticed. However, the impregnants were less effective when applied on specimens subjected to intermediate and long-term exposure to water. In dry conditions, pure-silane performed better than the water-based silane, although they had a similar performance when applied on wet specimens. In addition, increasing the internal moisture content has shown an adverse effect on the efficacy of both materials. [ABSTRACT FROM AUTHOR]

Unbonded fiber-reinforced elastomeric isolators (FREIs) were initially proposed as a potential low-cost alternative to conventional steel-reinforced elastomeric isolators (SREIs). FREIs are similar to SREIs but comparatively lightweight as the steel components from SREIs have been replaced with polymer fibers in FREIs. Subsequent experimental investigations identified that unbonded FREIs have desirable characteristics for seismic isolation due to the unbonded application and fiber reinforcement. The unbonded application removes mechanical fasteners, relying on friction to transfer horizontal loads, further reducing the cost. However, the unbonded application also introduces limitations, being susceptible to slip in certain loading conditions and being incapable of resisting tensile forces. In this paper, the concept of partially bonded FREIs (PB-FREIs), a proposed solution to these limitations, is further investigated experimentally with nominal vertical tensile loads. It is shown that PB-FREIs can achieve similar properties to an unbonded FREI with a vertical compressive load. [ABSTRACT FROM AUTHOR]

Key performance indicators (KPIs) evaluate different aspects of projects and are used to determine the health status of projects. While there is considerable work on project quantitative performance prediction, less attention, however, has been directed towards qualitative performance prediction. This paper offers a novel framework for qualitatively measuring and predicting six important construction project KPIs using the neuro-fuzzy technique. Neuro-fuzzy models are developed to map the KPIs of three critical project stages to whole project KPIs. Subtractive clustering is utilized to automatically generate initial fuzzy inference system (FIS) models and the artificial neural network (ANN) technique is used to tune the parameters of the initial FIS models. The relative weight of each KPI is determined using a series of computing methods namely, analytic hierarchy process (AHP) and genetic algorithm (GA), to generate the performance indicator (PI). The developed models are validated with real project data showing that the rate of error is reasonably low. The results show that the AHP method is more accurate when compared to the GA method. This framework can be used in building construction projects to help decision-makers evaluate the performance of their projects. [ABSTRACT FROM AUTHOR]

Agricultural field equipment are typically equipped with wide single tires with particular tire tread and low inflation working pressures. Because of the significant differences with standard truck tires, the effect of flotation implement tire on pavement performance and load associated damage is likely to differ. This paper presents the results of an experimental research project where flotation tires were used to test the response of an instrumented flexible pavement built in an indoor test pit. The effect of load, tire pressure, and tire type was investigated as part of the study. Based on the collected results, the tire type and design greatly influence the pavement response. The critical and governing pavement damage mechanism was found to be subgrade structural rutting. Wide specialty tires were found to generally induce less damage than standard truck tires. A method for axle weight adjustment for wide farm tires was proposed as part of the project. [ABSTRACT FROM AUTHOR]

Drop manholes prevent excessive flow velocity and provide energy dissipation in steep urban sewer and drainage systems. Their poor hydraulic performance under Regime R2, in which the inlet jet collides with the manhole outlet, was improved by the jet-breaker. However, this device should still be properly sized to efficiently enhance manhole operation. In this paper, effects of jet-breaker length, width, sagitta, angle, and inlet pipe filling ratio on drop manhole performance, were investigated experimentally. Two-level factorial design and dimensional analysis were both utilized to design the experiments to study drop manhole energy dissipation and air demand as responses. Statistical analysis of the results revealed both significant design factors and regression models for each response. Neither jet-breaker length nor width had significant effects. However, the responses were improved by increasing both jet-breaker angle and inlet pipe filling ratio. Jet-breaker sagitta had a different effect on each response; a flat plate was more appropriate for energy dissipation while a curved plate decreased air demand. Simultaneous analysis of regression models determined the proper levels of significant design factors as 80% filling ratio of the inlet pipe, jet-breaker angle at 70°, and its sagitta equal to 0. [ABSTRACT FROM AUTHOR]

Water distribution networks (WDNs) are one of the most important elements of urban infrastructure and require large investment for construction. Design of WDNs is classified as a large combinatorial discrete nonlinear optimization problem. The main concerns associated with the optimization of such networks are the nonlinearity of the discharge-head loss relationships for pipes and the discrete nature of pipe sizes. Due to these issues, this problem is widely considered to be a benchmark problem for testing and evaluating the performance of nonlinear and heuristic optimization algorithms. This paper compares different techniques, all based on evolutionary algorithms (EAs), which yield optimal solutions for least-cost design of WDNs. All of these algorithms search for the global optimum starting from populations of solutions, rather than from a single solution, as in Newton-based search methods. They use different operators to improve the performance of many solutions over repeated iterations. Ten EAs, four of them for the first time, are applied to the design of three networks and their performance in terms of the least cost, under different stopping criteria, are evaluated. Statistical information for 20 executions of the ten algorithms is summarized, and Friedman tests are conducted. Results show that, for the two-loop benchmark network, the particle swarm optimization gravitational search and biology and bioinformatics global optimization algorithms efficiently converge to the global optimum, but perform poorly for large networks. In contrast, given a sufficient number of function evaluations, the covariance matrix adaptation evolution strategy and soccer league competition algorithm consistently converge to the global optimum, for large networks. [ABSTRACT FROM AUTHOR]

Accurate prediction of recoverable train delay can support the train dispatchers' decision-making with timetable rescheduling and improving service reliability. In this paper, we present the results of an effort aimed to develop primary delay recovery (PDR) predictor model using train operation records from Wuhan-Guangzhou (W-G) high-speed railway. To this end, we first identified the main variables that contribute to delay, including dwell buffer time, running buffer time, magnitude of primary delay time, and individual sections' influence. Different models are applied and calibrated to predict the PDR. The validation results on test datasets indicate that the random forest regression (RFR) model outperforms the other three alternative models, namely, multiple linear regression (MLR), support vector machine (SVM), and artificial neural networks (ANN) regarding prediction accuracy measure. Specifically, the evaluation results show that when the prediction tolerance is less than 1 min, the RFR model can achieve up to 80.4% of prediction accuracy, while the accuracy level is 44.4%, 78.5%, and 78.5% for MLR, SVM, and ANN models, respectively. [ABSTRACT FROM AUTHOR]

Different types of distress occur in asphalt concrete pavements due to lack of bonding between existing old layer and overlay. Therefore, this paper evaluates the bonding strength between sand asphalt mixture as overlay and roller compacted concrete (RCC) as the existing layer. Four types of tack coat including crumb rubber modified (CRM), grade 60/70 binder, cationic slow-setting (CSS), and cationic rapid-setting (CRS) emulsion were considered, with 200, 400, and 600 g/m2 dosages. Different RCC surface temperatures including 0, 25, and 60 °C were chosen to evaluate the effect of ambient temperature on the bonding strength. Results showed that CRM and 60/70 binders have higher bonding strength in comparison to emulsions. The bonding strength at 0 °C for all types of tack coat was significantly lower than other temperatures. The optimum application rates of 200 g/m2 and 400 g/m2 were selected for the CSS and CRS emulsified binders respectively. The optimum application rate for the 60/70 and CRM binders was selected as 600 g/m2. [ABSTRACT FROM AUTHOR]

The paper investigates increasing permeate flux (%) of the disc membrane which can improve the quality of rubber industrial effluent of Tripura. Response surface methodology was used to optimize the independent influencing parameters to improve the permeate flux. The effect of different influencing parameters like operating pressure, membrane pore size, and inlet feed velocity on membrane permeate flux were studied to determine the optimum operating conditions within the predefined boundary. The experiments were pre-planned and designed according to central composite rotatable design, and second-order polynomial regression model was developed for regression and analysis of variance study. Results show the membrane has maximum permeate flux (%) when the operating pressure is 14.50 Pa, pore size is 0.20 μm, and inlet feed velocity is 2.10 m/s. The Pareto analysis in the study established that the inlet velocity was the most influential parameter in the model equation. [ABSTRACT FROM AUTHOR]

An investigation into the optimum length of passing lanes on rural two-lane highways is presented in this paper. A passing lane is a short length of added lane to improve passing opportunities on two-lane two-way highways. The study utilized field data and traffic simulation in this investigation, with field data primarily used in calibrating and validating the traffic simulation program. A sensitivity analysis was conducted using traffic level and length of passing lane as the primary variables. The level of association between the reduction in platooning and study variables was examined. Study results showed that, within the range of passing lane length investigated in this study (0.5 mi to 3.0 mi), traffic performance continued to improve with the increase in passing lane length. Moreover, for the same target improvement in performance, the required passing lane length increases with the increase in traffic volume. The passing lane optimum lengths developed in this study all varied in the range between 0.80 and 2.0 miles depending on traffic volume. [ABSTRACT FROM AUTHOR]

Productivity measurement is a concern for both construction practitioners and researchers. In construction, productivity can be measured at three levels: activity, project, and industry. At the project level, previous studies focused on measuring the productivity of specific activities. In addition, existing project-level productivity metrics do not consider the effect of all resources used in a project. To effectively assess overall project performance, the productivity of all project activities and resources used must be taken into account. This study presents a framework that takes into consideration all resources used in a project and proposes a metric for measuring the total productivity of construction projects. A focus group session with experts, followed by questionnaire surveys, were used to assess the applicability of the framework. This paper makes a contribution by providing researchers and practitioners with a framework and tools for data collection and analysis of total construction project productivity. [ABSTRACT FROM AUTHOR]

In this paper, the moisture susceptibility of different bituminous binders with two substrates (glass and limestone) was investigated. To that end, the tensile strength of different combinations of bituminous binder–substrate bond was measured using a pull-off test. This test was adapted from the pneumatic adhesion tensile testing instrument (PATTI) test to improve repeatability. Samples were tested in dry condition and after a 7-day conditioning in hot water bath (60 °C). An analysis of variance (ANOVA) was performed on the test results. Overall, the results show that in dry condition, the pull-off strength is a function of the bituminous binder type rather than of the substrate type. After water conditioning, an increase in the pull-off strength was observed for the bituminous binder without polymers and coupled with glass substrate. This was associated with an increase in binder stiffness. For the limestone substrate, the effect of water conditioning was significant only for one type of binder. [ABSTRACT FROM AUTHOR]

An experimental study was conducted to determine the effect of deflection waveform on four-point flexural fatigue test results for hot mix asphalt. This paper reports how the waveform affects the fatigue resistance of an asphalt mixture and, consequently, the fatigue models of the material. The mix was tested at different strain levels under both haversine and sinusoidal deflection-controlled modes. The findings indicate that haversine displacement control testing results in a sinusoidal strain response of half the intended amplitude. This outcome was attributed to the viscoelastic nature of asphalt mixes. In the deflection controlled haversine test, permanent deformations lead to a new equilibrium neutral position of the beam and the force output follows a sinusoidal waveform. This produces erroneous fatigue results since the test assumptions do not match the actual test conditions. It is recommended to use a sinusoidal waveform to obtain consistent results. [ABSTRACT FROM AUTHOR]

Left turns may generate efficiency problems, which can be solved by appropriately prohibiting left turns. The goal of this paper is to propose a method for purpose of minimizing total travel times in urban road networks by prohibiting left turns. With left turn prohibition, the signal timing plan is optimized with the lane-based method because the method can adequately handle both signal timing optimization and lane assignment. The total travel time is calculated with link flows and link travel time being estimated with signal settings. As illustrated by numerical examples, prohibiting left turns reduces the total travel time of car traffic in road networks. As the left turn prohibition results can handle the randomness in the network, these results provide potential implications for congestion management. [ABSTRACT FROM AUTHOR]

Overtime and over-budget construction projects are not pleasant to any stakeholder. Stakeholders want construction projects to be completed without delay and excessive cost. It is possible to meet these objectives by using resource management techniques such as resource leveling. Due to the limitation of resources and different types of them in a construction project, optimizing the resource utilization is crucial. In this paper, a meta-heuristic simulated annealing resource leveling model is presented. The novelty of this model lies not only in the type of modeling and optimization but also in its assumptions. Our model simultaneously allows activities to split and considers a limitation in resource availabilities. The developed model was implemented in a computer program. Then, it was applied to an example from the literature of resource leveling. The model successfully solved the problem. The results of our model are compared with those already available in the literature. [ABSTRACT FROM AUTHOR]

Tunnelling under the York University Schulich Building was one of the milestones of the Toronto-York Spadina Subway Extension Project. The challenge was to bore the tunnel under a flagship building only one diameter below the foundation without a compensation grouting process. Intensive finite element structural and geotechnical analyses of the building and the tunnel were performed, together with monitoring field measurements. The results showed that compensation, included in the initial design, was not necessary to ensure the building's structural integrity. The tunnel monitoring during crossing confirmed the results of the performed analyses. The paper highlights the difficulty of deciding whether a compensation grouting is necessary or not when tunnelling under buildings and explains the procedure that was followed in this particular case. [ABSTRACT FROM AUTHOR]

The design of manholes dates back more than 100 years. However, there have been developments such as the use of new materials for the manufacture of manholes, and advances in inspection and maintenance technologies, allowing improvements to the shape of manholes. This paper presents an innovative design for manholes, created to overcome the challenges associated with the installation of separate sewer systems in narrow streets, common to both UK and EU cities. The traditional separate sewer system has two separate manholes. The proposed manhole combines these two manholes into one structure, with two separate chambers, to allow storm flow and foul flow to pass through the same manhole without mixing. The structural performance of the new design has been tested using mathematical modelling validated by experimental tests. The results are compared with the structural performance of traditional manholes. The new design shows an improved resistance to high live loads. [ABSTRACT FROM AUTHOR]

Hydraulic jumps on a large scale are turbulent, with high Reynolds number. It has been proven difficult to achieve this in previous studies of jumps as two-phase flow. This paper aims to investigate the behaviours of two-phase flow and air entrainment in jumps at relatively high Reynolds numbers. Model predictions of both oscillating and steady jumps at multiple values of Froude number are reported, along with verifications of the predictions using air volume fraction (AVF) measurements, and analytical and empirical solutions for the height of jump, roller length, and free surface. The model captures the macroscopic characters of the two types of jumps and velocity structures. The predicted AVF distributions are consistent with the velocity structures. For steady jumps, AVF profiles are roughly bell-shaped, but are heavier-tailed upward than downward. For oscillating jumps, AVF profiles are even more asymmetrical. The Reynolds number affects air entrainment and transport in two-phase flow. [ABSTRACT FROM AUTHOR]

During planning of repetitive build–operate–transfer (BOT) construction projects, investors and (or) investor-representatives are always faced with a challenging task to identify an optimal project plan that maximizes the investor's profit within a specified concession period. Minimizing project duration in BOT projects often results in additional costs, however, it increases the project operation period and accordingly increases the investor's profit. Optimal plan of constructing repetitive BOT projects requires identifying construction methods and the associated start and finish time of each construction activity according to the availability of resources and contractors. Traditional scheduling methods such as critical path method (CPM) networks do not provide efficient planning of repetitive construction projects as they (1) do not maintain crew work continuity as well as resources availability, and (2) often result in large and repetitive number of activities to model repetitive construction projects. This paper presents the development of an optimization model using linear scheduling method that identifies the near-optimal plan for constructing repetitive BOT projects to maximize the investor's profit. The development of this optimization model includes three steps: formulation phase that formulates the model decision variables, objective function, and constraints; implementation phase that executes the model computations using genetic algorithms and identifies the model inputs and outputs; and evaluation phase that verifies the model performance and document its value. A case study of a construction project is presented to illustrate the new capabilities of the model. The results of the model showed 21% profit increase as compared to the existing schedule adopted by the investor. [ABSTRACT FROM AUTHOR]

This paper deals with dynamic field testing of light-frame wood buildings with wood based shear walls. The primary objective of the investigation is to provide an estimate of the fundamental period of such buildings, through field testing and numerical modeling. An experimental program is established to perform ambient vibration testing on 41 light-frame wood buildings of both regular and irregular layouts, located in moderate to high seismic zones in different regions in Canada. The research objective is to develop a reliable method of estimating the building period of light-frame wood buildings and develop an accurate expression for building period estimate based on field testing and numerical modeling. The study found that significant scatter is observed in the measured data when plotted as a function of building height. Finite element (FE) models were developed and compared with the natural periods of the buildings with reasonable accuracy. Using the validated FE models to examine different commonly used stiffness models showed that in general current analysis approaches overestimate the building period. [ABSTRACT FROM AUTHOR]

This paper describes a study undertaken to assess the speed and safety effects of reducing speed limits from 50 to 30 km/h in school zones. Mean speeds and 85th percentile speeds were reduced by 12.2 and 11.6 km/h, respectively. Speed variation was also reduced, and the speed cumulative distributions shifted to the left, indicating further reductions for all speed ranges. The safety evaluation results revealed fatal and injury collisions were significantly reduced by 45.3% and injuries to vulnerable road users were reduced by 55.3%. In fact, for every 1 km/h reduction in mean speed, fatal and injury crashes were reduced by about 4%, which is consistent with findings from previous research. Neither spatial nor temporal collision migration or spillover effects were significant factors in the analysis. Consequently, the results of this study provide strong evidence that reducing speed limits to 30 km/h in school zones can bring significant safety benefits by reducing vehicular speeds and fatal and injury crashes. [ABSTRACT FROM AUTHOR]

One of the advanced methods of modeling activity duration is the multiple discrete-continuous extreme value (MDCEV) model. The translating satiation parameter of the model is intended to capture the constant marginal utility effect, but model testing shows that it does not do so. In this paper, the structure of the translating satiation parameter was modified to incorporate an additional parameter that enables the model to capture this effect. Two datasets from cities in Saudi Arabia and Germany were used to test the applicability of the modified model for any dataset. The results showed that the proposed model structure increased the accuracy of activity duration prediction by up to 74%. The modified model represents an improvement to the conventional MDCEV model in terms of accuracy and flexibility, and as such should be a valuable tool in transportation planning and management. [ABSTRACT FROM AUTHOR]

Currently, there is a lack of direct design provisions in structural codes and literature that address design temperatures in tunnel structures and thus it is common practice for designers to resort to bridge codes. The main focus of this paper is the study of the temperature distribution in concrete road tunnels due to ambient temperature. In this context, the temperature distributions of the Airport Trail Tunnel in Calgary, Alberta is studied using numerical modelling and long-term temperature monitoring data collected from the tunnel. The overall aim is to evaluate findings from the numerical analysis and sensor data with current Canadian structural code provisions considered in tunnel design in regards to temperature loads. From the investigation, it is determined that the design temperature range was within CSA S6, however CSA S6 underestimates the temperature gradient effect in the walls and slabs of the tunnel under study. [ABSTRACT FROM AUTHOR]

Continuous monitoring of productivity and assessment of its variations are crucial processes that significantly contribute to success of earthmoving projects. Numerous factors may lead to productivity variations. However, these factors are subjectively identified using manual knowledge-based expert judgment. Such manual recognition process is not only subject to errors but also time-consuming. There is a lack of research work that focuses on near real-time assessment of productivity variation and its effect on cost, schedule and effective utilization of resources in earthmoving projects. This paper presents a customized multi-source automated data acquisition model that acquires data from a variety of wireless sensing technologies. The acquired multi-sensor data are transmitted to a central MySQL database. Then a newly developed data fusion algorithm is applied for truck state recognition, and hence the duration of each earthmoving state. Multi-sensor data fusion facilitates measurement of actual productivity, and consequently the assessment of productivity ratios that support continuous monitoring of productivity variation in earthmoving operations. The developed tracking and monitoring model generates an early warning that supports proactive decisions to avoid schedule delays, cost overruns, and inefficient depletion of resources. A case study is used to reveal the applicability of the proposed model in monitoring and assessing actual productivity and its deviations from planned productivity. Finally, results are discussed and conclusions are drawn highlighting the features of the proposed model. [ABSTRACT FROM AUTHOR]

Indian traffic is highly heterogeneous consisting of all-inclusive vehicle characteristics, occupying any lateral position over the entire road width which results in vehicles continuous interaction with the neighbouring vehicles (in both longitudinal and lateral directions), indicating two-dimensional (2D) traffic manoeuvre, opposite to the traditional one-dimensional (1D) interaction of vehicles in lane based traffic. Certain modifications were made in the existing 1D models to describe the overtaking and lane changing manoeuvre of the mixed traffic stream. However, the continuous lateral manoeuvre of the no-lane based mixed traffic cannot be described by these parameters. This paper initially provides a brief review of different 2D behavioural models, which describe the longitudinal and lateral movements simultaneously. Also, the various existing commercially available traffic micro-simulation frameworks developed for representing the real traffic are reviewed. Different microscopic traffic parameters used in the existing simulation models to mimic the real-world traffic are identified, which can be used to understand the 2D traffic stream. [ABSTRACT FROM AUTHOR]

In this paper, we consider an adaptive system for controlling green times at junction. For this adaptive system, we present a multi-objective optimization model, which is much easier to solve than some existing models. Furthermore, to solve the new model, we suggest an algorithm, called NLRMNSGA-II, which is based on the nonlinear least regression and a modified non-dominated sorting genetic algorithm. Our numerical experiments indicate that the NLRMNSGA-II is an efficient algorithm for the considered adaptive system. [ABSTRACT FROM AUTHOR]

Universities are facing many challenges to their efforts to introduce building information modeling (BIM) in engineering education. Many research efforts have been dedicated to the subject and addressed some specific aspects of the issue. Thus, there is no comprehensive framework to provide decision-makers with practical and neutral guidelines. The framework proposed in this paper identifies the main challenges to address. A case study from a Canadian engineering school is used to evaluate and to validate the proposed framework, and to illustrate the challenges. The strategy of integrating BIM in engineering education should be based on the specific skills the students are expected to acquire. It is then possible to define the appropriate teaching approaches. An effective implementation strategy should be gradual to progressively raise community awareness, learn from mistakes, and identify best practices. A particular emphasis should be placed on the needs of the local industry. [ABSTRACT FROM AUTHOR]

Rear-end collisions represent a quarter to one-third of the total number of collisions occurring on North American roads. While there are several methods to mitigate rear-end collision effects, one way is to warn drivers about impending events using forward collision warning (FCW) systems. At the core of any FCW algorithm is a trigger distance at which a message is relayed to the driver to avoid rear-end collisions. The main goal of this paper is to propose a warning distance model based on naturalistic driver following behavior. This was achieved by investigating car-following events within a critical time-to-collision range. A total of 5785 candidate car-following events were identified for the model development from 2 months of naturalistic driving study data of 63 drivers. Using regression analysis, the minimum warning distance was linked to several performance measures. It was found that the relative speed, the host vehicle speed, and the host vehicle acceleration can significantly affect the minimum warning distance. To assess the performance of the developed algorithm, it was compared to six of the existing FCW algorithms in terms of warning distances. The results of the developed algorithm were consistent with the other perceptual FCW algorithms. However, the warning distances of the proposed algorithm were less than the distances produced by the kinematic algorithms. The proposed algorithm could be used as a minimum threshold to trigger an alert for an FCW algorithm. Since the proposed algorithm is developed based on actual driving data, it is expected to be more acceptable by drivers. However, the algorithm needs further testing in real-life to validate this expectation. [ABSTRACT FROM AUTHOR]

The performance of the fibre reinforced polymer (FRP) to reinforced concrete (RC) interface is vital to ensure desired design capacity. Without proper understanding of the interfacial behaviour it is impossible to develop an effective, efficient, and rational bonding technique. This paper presents the results of a comprehensive numerical investigation aimed to assess and better understand the debonding behaviour caused by different types of intermediate flexural crack distributions in FRP–RC strengthened beams. The model is based on damage mechanics modelling of concrete, a bilinear bond–slip relationship with softening to represent the interface, and a discrete crack approach to simulate crack propagation. The model also highlights how crack propagation and debonding is affected by the rate of change of moment. It is shown that the variation of crack spacing and rate of change of moment can significantly affect debonding crack propagation and strain development in the internal and external reinforcement, which directly influences debonding load. [ABSTRACT FROM AUTHOR]