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The two-part series of papers provides a survey on recent advances in Deep Reinforcement Learning (DRL) for solving partially observable Markov decision processes (POMDP) problems. Reinforcement Learning (RL) is an approach to simulate the human’s natural learning process, whose key is to let the agent learn by interacting with the stochastic environment. The fact that the agent has limited access to the information of the environment enables AI to be applied efficiently in most fields that require self-learning. It’s essential to have an organized investigation—we can make good comparisons and choose the best structures or algorithms when applying DRL in various applications. The first part of the overview introduces Markov Decision Processes (MDP) problems and Reinforcement Learning and applications of DRL for solving POMDP problems in games, robotics, and natural language processing. In part two, we continue to introduce applications in transportation, industries, communications and networking, etc. and discuss the limitations of DRL.

The first part of a two-part series of papers provides a survey on recent advances in Deep Reinforcement Learning (DRL) applications for solving partially observable Markov decision processes (POMDP) problems. Reinforcement Learning (RL) is an approach to simulate the human’s natural learning process, whose key is to let the agent learn by interacting with the stochastic environment. The fact that the agent has limited access to the information of the environment enables AI to be applied efficiently in most fields that require self-learning. Although efficient algorithms are being widely used, it seems essential to have an organized investigation—we can make good comparisons and choose the best structures or algorithms when applying DRL in various applications. In this overview, we introduce Markov Decision Processes (MDP) problems and Reinforcement Learning and applications of DRL for solving POMDP problems in games, robotics, and natural language processing. A follow-up paper will cover applications in transportation, communications and networking, and industries.

The advantages of nationwide coverage, secured mobile connectivity, licensed spectrum operations, interference mitigation and mobility robustness capabilities, LTE Advanced Pro (4.5G) cellular network is a highly suitable candidate for Unmanned Aerial Systems (UAS) Command and Control (C2) communication management within Urban Traffic Management of Unmanned Aerial Systems (uTM-UAS) that have been presented at the Drone Enable International Civil Aviation Organization’s UAS Industry Symposium. In this paper, coverage and performance assessment for sub-urban, urban and coastal areas in Singapore for up to 400 feet (121.92 metre) altitude is first performed. Utilizing the collected measurements with Atoll radio planning tool, a calibrated Standard Propagation Model (SPM) is proposed to simulate 4.5G coverage availability for entire Singapore airspace up to 400 feet altitude. This calibrated SPM considers pathloss correction due to angular-depression between UAS’ altitude and cell tower height to improve coverage prediction accuracy. The accuracy of less than 8dB error in variance between simulation and experimental results have been achieved. The calibrated model will be used to support the uTM-UAS to indicate suitable airspace in terms of communication coverage and performance to ensure safe UAS operations.

This paper analyses user equipment measurements and network performance indicators to address uplink power allocation problem in multi-vendor heterogeneous networks. First, the selection of optimal open-loop power control strategy is studied by comparing equal Power Spectral Density (PSD) strategy with Min-Median maximization strategy. Later, the best open-loop strategy is compared to closed-loop power control performance. The analysis show that the Min-Median scheme outperforms the equal PSD by balancing the performance and improving the uplink throughput by 30 %. In live deployment, uplink transmit power levels were observed to be higher than expected based on the open-loop power control strategy. Therefore, the equal PSD criterion is not able to balance the interference conditions between the network layers. Moreover, closed-loop power control strategy further improves the uplink throughput by 61 % if compared with the optimal OLPC configuration.

The increasing tendency to use urban civilian buildings for military purposes prompts the need for the assessment of their blast resistance. Many of these buildings are made of reinforced concrete (RC). Popular tools available for the assessment of existing RC structures in practice include guidelines and design standards, technical manuals and specialised software. These tools include certain assumptions based on scarcely available test data, as historically they were collected for military purposes. Efforts to transfer this knowledge from military to civilian applications are relatively recent and need be corroborated by further testing and numerical analysis. The objective of this paper is to present the results of field tests on full-scale RC members to check the validity of a number of assumptions routinely made in current numerical/analytical models. The data captured during the tests, including reflected pressure and member displacements, are compared with results of empirical and numerical models, in order to gauge the robustness and accuracy of the assumptions underpinning these models. Finally, recommendations are made for an expedient assessment of existing buildings based on simple methodologies.

A Single-Degree-of-Freedom (SDOF) model is used to determine the effect of axial load on column strength and stability during a blast event. The model, which accounts for the axial load–bending interaction (P–δ effect) and strain rate effect on the column dynamic response, is validated by comparing its results with experimental data from blast tests on full scale steel columns and with the results of the finite element software LS-DYNA. Maximum displacements and moments obtained from SDOF analysis are also compared with the results of the interaction formulas recommended by the Unified Facilities Criteria (UFC 3-340-02) design manual for steel structures. It is shown that the UFC method overestimates the column capacity for ductility ratios μ greater than one, irrespective of the axial load to Euler elastic buckling load ratio (P/Pe). Also for P/Pe > 0.5, even if μ

The re-centering phenomenon of superelastic Shape Memory Alloy (SMA) reinforced concrete is a unique characteristic that is appealing for structural applications, along with the ability to respond with stable hystereses and achieve similar strength and ductility to concrete reinforced with conventional deformed bars. The objective of this study was to investigate the structural performance of superelastic SMA reinforced concrete and to develop a preliminary constitutive model applicable to nonlinear finite element algorithms. Seven simply supported flexure-critical concrete beams, reinforced with either SMA bars in the critical region or conventional deformed reinforcement, were subjected to monotonic, cyclic, and reverse cyclic loading. The experiment results demonstrated the superior capacity of the SMA beams to recover inelastic displacements. The SMA beams sustained displacement ductility and strength capacity comparable to the conventional beams. Crack widths and crack spacing were larger in the SMA beams; however, upon removal of load, the crack openings were recovered. Energy dissipation was lower in the SMA beams, particularly when subjected to reverse cyclic loading. The constitutive model based on a trilinear backbone envelope response and linear unloading and reloading rules provided satisfactory simulations.

In this study, the dynamic response of typical wide-flange steel beams was experimentally evaluated under blast loading. A total of 13 beams were field tested using live explosives, where the charge size ranged from 50 to 250 kg of ammonium nitrate-fuel oil mixture, and the ground stand-off distance was from 7.0 to 10.3 m. Blast wave characteristics, including incident and reflected pressures, were recorded. In addition, time-dependent displacements, accelerations, and strains at different locations along the steel members were measured, and the postblast damage and mode of failure of the test specimens were observed. The blast load characteristics were compared with those obtained using the Technical Manual UFC 3-340-02 results. The displacement response results were used to validate the results obtained from a nonlinear dynamic analysis based on a single degree-of-freedom (SDOF) model. Results showed that the UFC 3-340-02 pressure predictions compare reasonably well with the measured pressure in the positive phase in terms of both the peak pressure and overall time variations. The SDOF model predicted the maximum displacements of beams in the elastic range reasonably well, but it overestimated them in the plastic range.

This paper presents detailed analysis of the results of field tests on 13 full scale wide flange steel beams subjected to blast loads generated by the detonation of up to 250 kg of ANFO explosive. The experimental results are analyzed using an equivalent Single-Degree-of-Freedom (SDOF) model of a beam, which includes material nonlinearity and strain rate effects. To account for strain rate effect on beam stiffness and strength, its full moment-curvature response is determined by dividing its cross-section into a number of layers and a strain rate-dependent stress-strain relationship, based on the Cowper–Symonds strain rate model, is used to capture the nonlinear stress distribution over the section. To determine the effects of higher modes of vibration and the variation of beam mechanical properties along its length on its dynamic response, the test beams are also analyzed using a Multi-Degree-of-Freedom (MDOF) model involving beam finite elements. Each element has two nodes and three degrees of freedom and is again divided into a number of layers to capture the strain rate effect and nonlinear stress distribution over its depth. The predicted displacements and strains by the two models are compared with the corresponding experimental data and the results show that for the given beams, the time-dependant deformations, internal forces, and moments can be adequately predicted by either model because the first mode of vibration is found to dominate their response; however, the use of a constant strain rate through the so-called Dynamic Increase Factor (DIF) can lead to highly conservative estimate of the actual strength of such members.

Laboratory tests are performed to investigate the effects of a new method of mixture proportioning on the creep and shrinkage characteristics of concrete made with recycled concrete aggregate (RCA). In this method, RCA is treated as a two component composite material consisting of residual mortar and natural aggregate; accordingly, when proportioning the concrete mixture, the relative amount and properties of each component are individually considered. The test variables include the mixture proportioning method, and the aggregate type. The results show that the amounts of creep and shrinkage in concretes made with coarse RCA, and proportioned by the new method, are comparable to, or even lower than, those in similar concretes made entirely with natural aggregates. Furthermore, it is demonstrated that by applying the proposed “residual mortar factor” to the existing ACI and CEB methods for calculating creep or shrinkage of conventional concrete, these methods could be also applied to predict the creep and shrinkage of RCA-concrete.

This paper presents the results of an analytical investigation of one-way unreinforced masonry (URM) walls retrofitted with externally anchored steel studs and subjected to blast loads. Using the wall geometrical and material properties, deflected shape, and crack pattern as input, a nonlinear model is developed to predict the inward force-displacement relationship of the retrofitted walls. In addition, using a rigid body analysis, a simple bilinear force-displacement relationship is developed to model the outward force-displacement relationship of the walls. Utilizing these two force-displacement relationships (resistance functions), a generalized single-degree-of-freedom (SDOF) model is developed to capture the nonlinear out-of-plane dynamic response of the retrofitted walls under blast loads. The SDOF model captured the experimentally observed displacement responses of the tested walls with reasonable accuracy. The model was also used to investigate the influence of block thickness, wall slenderness ra...

New standards for blast protection of buildings are currently being developed in the United States and Canada. In this regard, both standards are considering unreinforced masonry (URM) walls as particularly vulnerable to blast events and may not be used in blast-resisting structural systems. In this paper, the effectiveness of enforcing arching action as a cost-effective hardening technique for vertically spanning one-way URM walls under blast loads is investigated. A total of eight full-scale concrete-block URM walls were subjected to blast loads generated by high explosives. Enforcing URM walls arching between rigid supports significantly enhanced their out-of-plane blast resistance compared to similar nonarching (flexural) URM walls. Moreover, no fragments or debris were observed on the leeward side of the arching walls, indicating the potential of the proposed hardening technique in reducing the hazard level on the occupants of buildings with exterior URM walls. The improved performance is attributed ...

Six full-scale concrete masonry walls were tested under free-field blast loading using different charge sizes up to 250 kg of ammonium nitrate/fuel oil (ANFO) and at a constant stand-off distance of 15.0 m to cover a wide range of expected damage levels. Five walls were retrofitted with cold-formed steel studs anchored to the wall backs and were compared to the remaining as-built wall. Significant enhancement to the out-of-plane blast resistance of the retrofitted walls, compared to the as-built wall, was observed. This enhancement is attributed to the development of a tied-arch action in the retrofitted walls in which the masonry forms a compression strut while the steel studs serve as the tie. A simplified single-degree-of-freedom model was used to analyze the experimental results, and the model results agreed well with the observed damage levels and the resistances of the walls. In addition, the effectiveness of the proposed retrofit technique was evaluated in terms of strength enhancement and wall def...

The applicability of some major concrete design standards and other pertinent methods to calculate the concrete contribution to the shear resistance of reinforced recycled concrete (RRC) beams without stirrups is investigated. Results of a relatively comprehensive experimental program are used to compare the actual shear strength of the tested beams with their corresponding predicted values. The concrete mixes for the RRC beams were proportioned by the so-called Equivalent Mortar Volume (EMV) method. The method is predicated on the fact that recycled concrete aggregate (RCA) is a composite material, comprising mortar and natural aggregate, and the volumetric content and properties of each phase must be quantitatively accounted for when proportioning concrete mixes containing RCA. The test variables included in the test program are shear-span/depth ratio, beam size, RCA source, and coarse aggregate type. The results show that the shear capacity of a RRC beam is comparable, or sometimes superior, to that of a companion beam made of conventional concrete. The analyses performed in the current investigation show, contrary to previous findings, that existing shear design methods, such as the ACI and CSA codes methods, are applicable to RRC beams, provided the EMV method of mix design is used.

An experimental study is conducted to investigate the shear behaviour and strength of concrete beams made with coarse recycled concrete aggregate. The distinguishing feature of the beams is the manner in which their concrete mixture is proportioned. A new method of concrete mixture proportioning is used wherein recycled concrete aggregate is treated as a two-phase material comprising residual mortar and natural aggregate, and the relative amount and properties of each phase are considered. Using this method, several beams are made of recycled concrete aggregate-concrete and tested to study their serviceability and shear strength. For each beam its load–deflection curve, shear deformations, diagonal cracking load, crack pattern, ultimate shear strength, and failure mode are determined. The results show that the shear performance of reinforced recycled concrete aggregate-concrete beams is comparable, or even superior, to that of beams made entirely with natural aggregates at both the serviceability and ultimate limit states, and the current Canadian Standards Association, American Concrete Institute and Eurocode provisions for shear design can be used without any modification to design recycled concrete aggregate-concrete beams, provided the aforementioned mixture proportioning method is used.

Results of a comprehensive investigation about the durability of structural-grade concrete made with recycled concrete aggregate (RCA) are presented. The RCA-concrete mixes were proportioned using a new concrete mix design method, termed the equivalent mortar volume (EMV) method. The EMV method is based on the hypothesis that RCA is a composite material comprising mortar and natural aggregate; therefore, when proportioning a concrete mixture containing RCA, one must account for the relative amount and properties of each the two components and adjust both the fresh coarse aggregate and fresh paste content of the mix accordingly. Tests were conducted to study the freeze–thaw, chloride penetration and carbonation resistances of the mixes proportioned by the EMV method and by the conventional method. Results of the test showed that RCA-concrete mixes proportioned by the EMV method have higher resistance to freeze–thaw action, chloride penetration and carbonation than those designed with the conventional method, and they satisfy the current requirements for concrete exposed to severe environments.

As the supply of suitable fresh aggregates in some locations is rapidly dwindling and such aggregates need to be transported from distant locations, there will be more and more economic and environmental reasons to use recycled concrete aggregates in making new concrete. The nature and properties of recycled concrete aggregates have a definite impact on the performance of recycled aggregate concrete and the effects can vary considerably. Existing literature and studies conducted by the authors have shown that the amount and properties of the residual mortar in the recycled concrete aggregates significantly affect the mechanical and durability properties of the new concrete. Consequently, a quick laboratory method was developed to determine the residual mortar content of recycled concrete aggregates, to serve as a quality control tool for such aggregates. In order to validate the results obtained by that laboratory test procedure, image analysis was used to quantify the residual mortar content in the different size fractions of the recycled concrete aggregates tested. The results confirmed that the quick laboratory test provides an accurate measurement of the residual mortar content in recycled concrete aggregates.

The Ontario Ministry of Transportation has installed 27 changeable message signs (CMSs) strategically upstream of express–collector transfer locations on Highway 401 in Toronto, Ontario, Canada. Motorists are informed by the CMSs of traffic conditions downstream of the transfer location to help them decide whether to take the next transfer. Loop detectors are installed at the transfer locations to measure traffic flow. The dynamic impacts of CMS messages on traffic diversion are evaluated by using 3 years of loop detector data, from 2003 to 2005. Time-series plots of aggregated diversion rates show that the initial transient response to the message change is significant and that, in addition to the messages themselves, the occurrence of a message change plays a vital role in influencing downstream diversion. Aggregate diversion rate plots also reveal that the logic underlying the Highway 401 CMSs may be causing the signs to react to diversion rate changes on many occasions, thereby closing a feedback control loop that effectively regulates the downstream diversion rates.

To alleviate traffic congestion and safety concerns on the Gardiner Expressway in Toronto, Ontario, Canada, the City of Toronto has elected to implement scheduled closures for the two on-ramps since early 1970s. This study investigates the traffic impacts of the daily on-ramp closures at Gardiner Expressway and Jameson Avenue. The average changes to traffic flow variables such as traffic volume throughput due to the ramp closures are computed quantitatively. Results show that ramp closure has resulted in smoother traffic flow and higher travel speed but not higher traffic throughput on the expressway. Ramp reopening causes a spike in speed variations as measured by upstream detectors. The network performance metrics (vehicle hours traveled, vehicle kilometers traveled, delay, and travel time) are computed and analyzed to determine the performance benefits of the ramp closures. The travel time saving in the area due to the ramp closure is estimated to be 225 vehicle-hours per day.

Accidental or premeditated explosions have detrimental effects on the infrastructure near the center of explosion and pose major threats to human life. Thus, research is currently underway to study the effects of explosions on infrastructure systems with the ultimate goal of minimizing infrastructure damage and saving lives. Because reinforced concrete is the most common building material used in blast-resistant infrastructure design and construction, understanding the effect of blast loads on reinforced concrete components is essential to reaching this goal. The prevailing design philosophy for blast-resistant structures is energy dissipation through reinforcement yielding (ductility) and large bending deformations without the incidence of nonductile failure modes such as shear and bond. However, information regarding the bond behavior and strength of steel reinforcement–concrete bonds under blast loads is rather scant; therefore, this paper reports on an experimental program designed to investigate the strain rate effect on steel reinforcement–concrete bond. Reinforced concrete beams longitudinally reinforced with 15M, 20M, or 25M were tested in a shock tube under simulated blast loading. The test results show that high strain rate increases the steel reinforcement–concrete bond strength and thus, that the static load development lengths of these bars are adequate for developing their dynamic yield strengths at high strain rate. The dynamic increase factor for bond stress is determined to be 1.11 for 15M, 2.24 for 20M, and 3.68 for 25M bar.

This paper presents the experimental results of a study investigating the effectiveness of using externally bonded fiber-reinforced polymer (FRP) tow sheets for in-plane bending strengthening and repair of reinforced concrete (RC) shear walls. The repair/strengthening scheme is designed to enhance the flexural load-carrying capacity of the walls and prevent brittle shear-related failures. The experimental program consisted of the performance evaluation of the FRP system in seven RC shear wall specimens tested to failure under lateral loads. The effectiveness of two different anchoring systems to transfer the loads carried by the FRP sheets to the supporting elements of the wall was also investigated. The experimental results showed that the FRP system was successful in restoring (in repair applications) and increasing (in strengthening applications) the initial stiffness and ultimate load-carrying capacity of the walls, while maintaining a ductile response behavior and avoiding brittle shear failu...

Presented is a real-world testbed for Automatic Incident Detection (AID) systems that consists of an online data warehouse storing a month of traffic video, the corresponding traffic data and an operator log of incident start/end times. A proof-of-concept field evaluation is conducted whereby the testbed is used to calibrate, and then analyze the performance of four AID systems: California Algorithm 8, McMaster Algorithm, GAID Algorithm, and Citlog-VisioPAD. The pilot evaluation shows considerable advantages of the testbed in its ability to analyse the performance of the AID systems.

A new test bed for automatic incident detection (AID) systems uses real-time traffic video and data feeds from the Ontario, Canada, Ministry of Transportation COMPASS advanced traffic management system. This new test bed, called the AID comparison and analysis tool (AID CAAT), consists largely of a data warehouse storing a significant amount of traffic video, the corresponding traffic data, and an accurate log of incident start and end times. Also presented is a proof-of-concept field evaluation whereby the AID CAAT is used to calibrate and then analyze the performance of three AID algorithms: California Algorithm 8, the McMaster algorithm, and the genetic adaptive incident detection algorithm. In the calibration and testing process, nuisance rate and false normal rate are introduced as two new performance measures to supplement the three traditional measures (detection rate, false alarm rate, and mean time to detection). Further, the pilot evaluation shows the considerable advantages of AID CAAT in its ability to investigate the impact of freeway geometry, traffic flow rate, and traffic sensor spacing on the performance of the three AID algorithms. This work represents the first stage in a series of further tests to develop a set of AID algorithm deployment guidelines.

Recent natural hazards have exposed the dire consequence of damage and impact upon the built environment. It appears that one of the biggest challenges to the natural hazard mitigation community is how to improve the performance of older building and infrastructure to enhance their ability to withstand natural hazards. By improving their performance, the risk associated with buildings and infrastructure against natural hazards can be mitigated. Within the context of risk management of buildings against earthquakes, the general practice is to follow a three-step process, namely screening, evaluation and mitigation. Screening constitutes a preliminary evaluation process and sets priority for detailed evaluation. Evaluation compares a built environment with code requirements for new construction and sets priority for mitigation. Mitigation can be achieved by means of retrofit or replacement. Retrofit is intended to improve the performance of built environment as required. Replacement may be the only viable solution when economical, technical and environmental considerations are account for.

Structural engineers often limit their involvement in sustainability to material selection and recycling. Few structural engineers recognize the relationship between sustainability and disaster resilience. In response, the Sustainability Committee of the Structural Engineering Institute wrote a committee report to raise awareness of and provide guidance on the pertinent issues. This paper highlights the salient parts of the committee report. The introduction explains the relationship between sustainability and resilience and reviews the impacts of natural disasters. The following sections discuss general consideration for resilient design and summarize efforts to promote resilience and guidance for resilient design. Next are discussed current efforts to quantify the connection between disaster resilience and sustainability. The paper concludes with suggestions for structural engineers who are interested in supporting disaster resilience and sustainability.

In this study, 13 typical wide-flange steel columns, each carrying an axial load equal to 25% of its axial capacity, are field tested using live explosives, involving charge size of 50 to 250 kg of ammonium nitrate/fuel oil (ANFO) and ground stand-off distance of 7.0 to 10.3 m. The reflected pressure time histories, time-dependent displacements, accelerations, and strains of the columns are measured, and their postblast damages and failure modes are reported. Maximum deformations, vibration periods, strain-rate, and contributing modes in the dynamic response of the columns are compared to those of companion steel beams (without axial load) tested in the same setup. Results show that columns that exhibit elastic response, due to the elongation of the column vibration period caused by the axial load, the lateral deformation caused by blast load is reduced rather than magnified by the axial load. The axial-bending interaction, or P-δ effect, may be neglected for steel columns with axial load up to 25...

The new ASCE59-11 standards currently limit the use of unreinforced masonry (URM) walls in blast-resistant construction, regardless of the wall boundary conditions. This is attributable in part to the lack of experimental and analytical studies focusing on evaluating the response of URM walls under blast when the walls are forced to arch between the surrounding frame members. In this paper, the out-of-plane displacement response and structural stability of one-way vertical arching URM walls subjected to blast loads are investigated. A simple bilinear moment-rotation relationship is developed to simulate the arching wall responses. The model takes into account the masonry material strength, thrust forces, and wall geometry. Time-response analyses were performed using both single-degree-of-freedom (SDOF) and two-degrees-of-freedom (2DOF) models. Both models take into account the rocking phenomenon and second-order effects. Responses generated by both models were validated using experimental data reported previously. For preliminary design, performance charts were developed to correlate the effects of the wall slenderness ratio, masonry strength, and block size to the wall response under different levels of blast loads. The developed model and charts can be used as simple and quick calculation tools to estimate the required thickness, height, and strength of the wall under an expected blast threat when hardening of URM walls is necessary, with arching being considered as one of the alternatives.

This paper presents results of a collaborative study that is being carried out by the Thermal Processing Laboratory (TPL), the Department of Civil Engineering and Public Works and Government Services Canada (PWGSC). The main objective of this study is to investigate the feasibility of passive means to achieve net-zero energy (NZE) in federal buildings in Canada.

A significant portion of the existing building stock constructed prior to the enactment of modern seismic design provisions consists of Gravity-Load-Designed Reinforced Concrete (GLDRC) frames and unreinforced masonry infill walls which were used as partition walls in those buildings. Common construction practice before modern seismic design codes appeared, allowed the use of columns lap splices above the slab in each floor or above the foundation. The splices were typically 20 to 24 longitudinal bar diameters in length. Shear reinforcement was in the form of stirrups with 90-degree bends and spaced at half the depth of the frame member. As a result, the section at the base of these columns is unconfined and susceptible to shear failure or to a premature failure of the lap splices before yielding of the longitudinal bars, under reversed cyclic loadings in the event of an earthquake. The masonry infill walls used as partitions were often ignored by design engineers since such walls were considered as non resistant architectural elements. However, lessons learned from past earthquakes and from several tests performed have shown that those walls tend to interact with the bounding frame when the structural system is subjected to moderate or severe earthquake ground motions and that such interaction may not be beneficial to the performance of the structure. This paper presents the results of a series of tests, one monotonic and several shake table tests, conducted on two similar 1/2 scale gravity-load-designed reinforced concrete frames containing an unreinforced masonry infill wall built using hollow concrete blocks. One specimen was subjected to a static monotonic lateral loading and the other to prescribed simulated ground motions at different intensities to identify the interaction between the reinforced concrete frame and the masonry infill wall, the degradation in stiffness, and failure mechanism. The tests were conducted at the Earthquake Engineering Research Facility at the University of British Columbia in Vancouver, Canada.

Of the approximately 11 million tonnes of annual solid concrete and demolition waste (CD only a very small portion of the concrete waste is reused in building construction. Considering the fact that usable natural aggregate (NA) supplies are diminishing, there will be a high demand for recycled concrete aggregates (RCA) to be used in the so called ldquogreen concrete (GC)rdquo. Using recycled concrete as aggregate will help reduce the total cost of concrete production because aggregates need not be hauled from remote locations, but obtained locally. The combination of RCA with significant quantities of fly ash or slag as replacement for Portland cement is particularly attractive from both economic and environmental perspectives. GC will reduce the demand for natural resources, the associated energy consumption, and green house gas (GHG) emissions required to produce aggregates and cement. These reductions can be considered as one of the construction industry's major contributions to Canada's GHG emission reduction objective. Although there are some guidelines/specifications established by different countries such as the UK and Japan, currently, there are no established guidelines for producing GC in Canada. This paper presents the environmental and economic benefits of increasing the use of GC in the construction industry and highlights the objectives of an ongoing research by the authors on GC.

The ITS Centre and Testbed (ICAT) is a university-based facility that enables the research and development of advanced computer analysis and control algorithms that aim at improving the operational efficiency of our transportation system. The ICAT has live traffic surveillance data and video streams from the Ontario Ministry of Transportation and the City of Toronto through dedicated fibre-optic connections. The ICAT database stores 20-second loop detector data, messages displayed on changeable message signs (CMS), operator incident logs and 3-minute snap-shots of camera images. These data can be accessed by practitioners and researchers using a Web interface anywhere in the world. This paper describes some of the technical design choices involved in the development of such a research facility, and the reasons behind them. In particular, the communications system design, software and hardware architecture, as well as the general design philosophy, are presented. The archived data is made available to researchers and practitioners via the ICAT Website. Some specific features of the ICAT Website are presented to illustrate usage of the system

This paper describes the results of experiments carried out to investigate the performance in fire of concrete slabs reinforced with carbon or glass fiber fiber-reinforced polymer (FRP) bars. Several variables were examined to determine which were critical to the fire resistance of these slabs. The parameters examined included the reinforcement type, slab thickness, concrete cover thickness to the reinforcement, the aggregate type, and the effectiveness of other fire insulation. The thickness of the concrete cover to the reinforcement and the type of reinforcement were found to be the key parameters in determining the fire resistance of FRP-reinforced slabs. Overall, the results indicated that the qualitative and heat transfer behavior of FRP-reinforced slabs was similar to that of steel-reinforced slabs.

Recycling concrete from demolition of existing structures and using it as recycled concrete aggregates (RCAs) in structural-grade concrete have significant economic and environmental benefits. Currently, only a small portion of the concrete waste is reused in building construction, while most of it is used as either pavement base course or sent to landfills for disposal. The lack of confidence in the material properties of the concrete produced with RCAs is generally the main reason for its under-utilization in structural concrete. It has been demonstrated in the literature that the amount of residual mortar attached to the original (or “virgin”) aggregate particles is one of the factors affecting the material properties of RCAs. Therefore, before using RCAs in new concrete, it is crucial that the residual mortar content (RMC) is determined accurately; however, currently there is no standard procedure to determine this quantity. In this paper, an experimental method is proposed to determine the RMC of RCAs. The method comprises a combination of mechanical and chemical stresses that disintegrate the residual mortar and destroy the bond between the mortar and the natural aggregates. The mechanical stresses are created through subjecting RCA to freeze-and-thaw action, while the chemical degradation is achieved through exposure of the RCA to a sodium sulphate solution. The results of the proposed test procedure are validated by means of comprehensive image analysis. With the proposed approach, the attached residual mortar can be adequately removed, and the residual mortar content can be determined.