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Clean heating transformation and photovoltaic (PV) promotion gradually have become the keys to realize dual carbon strategy goals. Based on this, the combined application of building-integrated PV (BIPV) systems and air-source heat pump (ASHP) systems has received widespread attention. However, the current combined system still presents problems such as the mismatching in time between PV output and heating load. Therefore, in this paper, a novel BIPV and ASHP coupling system is proposed, and the operation parameters were optimized using low-carbon community as an example. A conventional PV and heat pump (HP) combined system, ASHP heating, and coal-fired heating were employed as the baseline and compared with the novel system. The results show that the optimized system can improve the PV power local accommodation rate by 43% compared with a conventional PV and ASHP coupling system. In terms of economic and environmental benefits, the operating cost of the optimized system is 50% of the cost of the ASHP system. Compared with coal-fired heating system, the annual air pollutant and carbon emissions can be reduced by 92% and 57%, respectively. The system also can improve the stability of power grid operation. The demand for power capacity can be improved by 62% and the annual load balance of the power grid can be improved by 29.5%. [ABSTRACT FROM AUTHOR]

Placing fresh cement concrete is not permitted during cold weather under normal conditions due to the risk of frost damage. On the other hand, electrically conductive concrete can be used for deicing/snow-melting applications. This paper presents laboratory investigations to develop electrically conductive cold weather concrete (ECCWC) that can be cast and cured below freezing temperatures and has sufficient electrical conductivity for Joule heating. The concrete has additive-based freeze protection (ABFP) systems that consist of optimized amounts of accelerators and corrosion-inhibiting admixtures. Several mixture proportions were made with 0.5%, 0.75%, and 1.0% carbon fibers by volume of concrete to increase the concrete's conductivity. ECCWC specimens were mixed, cast, and cured at −5°C. The measured freezing points of fresh concrete mixtures were below −5°C. The compressive strength development of ECCWC cured at −5°C was slow compared with the strength development of conductive concrete cured at 20°C. However, ECCWC could reach 55 MPa at 28 days of age. The temperature of hardened ECCWC increased by 18.5°C within 20 min when subjected to a potential difference of 30 V (alternating current). ABFP implemented in the ECCWC mixtures reduces the risk of frost damage and provides the opportunity to place fresh conductive cold weather concrete at ambient temperatures of −5°C without the need for taking curing precautions. The developed ECCWC introduces a new method for constructing multifunctional concrete structures to be placed and cured in cold regions. [ABSTRACT FROM AUTHOR]

This paper is concerned with electrically heated asphalt pavements; it numerically explores the possibility of such technology to actively suppress frost penetration under seasonal cold-weather conditions. A thermal model is outlined for the investigation based on the one-dimensional heat equation including latent heat effects. This model is applied to a multilayer medium containing a buried heat source representing the heating system. Utilizing cold-climate weather data from northern Finland, calculations were performed to track the evolution of the frost front depth in an idealized pavement structure with no heating. Then the model calculations were repeated with the heating activated. A parametric study was performed with different heat production intensities and several embedment depths for the heating system. It is numerically demonstrated that embedded electrical heating can suppress frost penetration depth and duration in asphalt pavements, rendering the explored application practically feasible. [ABSTRACT FROM AUTHOR]

Compressed-air energy storage has been considered as a promising technology to smooth the fluctuations of renewable energy sources and improve the peak-shaving flexibility capacity of power systems. In order to improve the energy degree of compression heat and enhance the system performance, the current paper described a novel combined heating and power system that integrates compressed-air energy storage with thermochemical technology. In the proposed system, the compression heat is coupled with methanol decomposition reaction to convert the thermal energy to chemical energy (H2 and CO). A sensitivity analysis was carried out to investigate the effects of five key parameters on the system performance. The results indicated that higher values of air-to-methanol ratio, pressure ratio, and isentropic efficiency of gas turbine have positive influences on the thermodynamic performance of the proposed system. In addition, the multiobjective optimization was implemented to ascertain the optimum performance from the aspect of thermodynamics and economics. The optimal condition selected using the technique for order preference by similarity to an ideal solution (TOPSIS) method demonstrated that the exergy efficiency and levelized cost of energy of the proposed system are 39.42% and $96.58/MWh , respectively. [ABSTRACT FROM AUTHOR]

The energy dissipated per cycle and the characteristic strength of lead-rubber bearings reduce with increasing number of cycles as a result of heating of the lead core. The reduction is substantial depending on the geometric characteristics of the bearing and the speed of motion. This paper presents a theory that is capable of predicting the dependency on time of the characteristic strength and energy dissipated of lead-rubber bearings. The theory is based on predicting the temperature of the lead core and relating the temperature to the strength. A much simpler theory is also presented based on neglect of heat conduction through the steel shim and end plates of the bearing. The theory is useful in predicting the cyclic behavior of lead-rubber bearings for simplified analysis, in extrapolating experimental data from one scale to another and in developing models for dynamic response history analysis of seismically isolated structures that account for the time-dependent mechanical properties of the bearings. A companion paper presents results of eight tests of six lead-rubber bearings that provide verification of the theoretical solution. [ABSTRACT FROM AUTHOR]

A thermoeconomic model for a double-stage coupled heat pump (DSCHP) with finite-rate heat transfer, heat leakage, and internal irreversibility has been developed. The heating load per unit total cost has been taken as the objective function. The optimal performance characteristics of the DSCHP have been discussed in detail and the optimum design parameters have been deduced analytically. The theoretical model has been exemplified in a particular case study. The investigation results demonstrate that the model is accurate to within 15% of the experimental data. The DCSHP design, with thermoeconomic optimization, leads to a significant increase of the specific heating load and a clear improvement of the economic performance with a small decrease of the coefficient of performance. When the values of ambient temperature, irreversibility of cycle I, irreversibility of cycle II, and investment cost per unit power have the same variation (5%), the objective function changes about 5, 5, 4.4, and 4.5%, respectively. The present paper provides a theoretical basis for design, thermoeconomic performance evaluation, and improvements of the DSCHP system. [ABSTRACT FROM AUTHOR]

The present paper conducts the experimental evaluation of the performance of a regenerative organic Rankine cycle (ORC) system working with refrigerant R123 and generating 10-kW-level power. The ORC system consists of an axial-flow single-stage turbine, a regenerator, an evaporator, a condenser, and a pump. The regenerative ORC and the basic ORC system efficiency are evaluated under the same conditions. The degree of superheat of the turbine inlet vapor is controlled by the evaporating temperature. The cooling water flow rate is controlled by adjusting the opening of the valve. The experiment results show that the thermal efficiency of the regenerative ORC is higher than that of the basic ORC by about 25%. The thermal efficiency of basic ORC with saturated vapor at turbine inlet is higher than that with superheated vapor by 3.2%, and the thermal efficiency of the regenerative ORC with saturated vapor at turbine inlet is higher than that with superheated vapor by 4.36%. The enthalpy drop across the turbine and the thermal efficiency of regenerative ORC both increase with increasing cooling water flow rate. The superheating at turbine inlet should be avoided, while a large cooling water flow rate should be considered to obtain higher system efficiency. [ABSTRACT FROM AUTHOR]

The first passive house (PH) was built in Germany in 1991. Since then several empirical design solutions have been developed, meeting the requirements of the PH standard proposed by the Passive House Institute (PHI) of Darmstadt, Germany. These design solutions have spread throughout central and western Europe and tend to be implemented in areas with a quite different climate than Germany's, such as southeastern Europe. This paper focuses on the question of whether the German design solutions would ensure the fulfillment of PH standard requirements in the latitudes of Romania. The paper compares general climate conditions for 22 towns in Germany and Romania. Further analysis is performed by estimating the energetic performance of a prototype passive building located in any of those 22 towns. The prototype passive building is AMVIC PH built in 2008 in Bragadiru (near Bucharest, Romania). It appears that the design solutions developed in Germany may be relaxed (for example, the thermal insulation may be reduced) when implemented for latitudes lower than 45°N. [ABSTRACT FROM AUTHOR]

This paper summarizes the results from a comprehensive experimental program in an effort to better understand the phenomenon of viscous heating of fluid dampers under small-stroke (wind loading) and large-stroke (earthquake loading) motions. Two dampers, one with 15-kip and one with 250-kip force output at peak design velocity, have been instrumented and tested under various amplitudes and frequencies. Temperature histories at different locations along the damper casing and within the silicon fluid that undergoes the shearing action have been recorded. Experimental data under small-stroke motions of the 250-kip damper showed that a single closed-form expression derived from first principles is capable of predicting the temperature rise at different locations of the damper with fidelity. The recorded data under long-stroke motions suggest a two-parameter law of cooling that allows the estimation of the internal temperature of the silicon oil once the external temperature on the damper casing is known. The presented cooling law is an extension of Newton’s law of cooling. The study concludes that for both dampers, the same values of the model parameters provide a good approximation of the cooling behavior. The study presents a valuable formula that can be used in practice to estimate the internal fluid temperature of the damper given the external shell temperature. [ABSTRACT FROM AUTHOR]

This paper describes the experimental methods developed to understand the self-healing or progressive erosion of core cracks in earth dams. Concentrated leaks through two types of core cracks are simulated experimentally in flow cells of different configurations. Results of experimental investigations indicate that the current empirical filter criterion for base soils with fines content more than 85%, which stipulates that (D15F/d85B) should be less than 9, is conservative. However, analysis of experimental results suggests that the (D15F/d85B) ratios can not indicate the rate of self-healing or progressive erosion. It also leads to a conclusion that mechanistic understanding, rather than another improved empirical criterion, may be needed for quantitative prediction of self-healing or progressive erosion. In this study, we identified two groups of quantitative parameters influencing the mechanism of self-healing: (1) characteristics of base soils and filters, and (2) hydraulic, geometric, and physicochemical conditions. Experimental methods are presented to evaluate these parameters for which no standardized methods are reported in the current literature. [ABSTRACT FROM AUTHOR]

This paper presents the results from experimental investigations focused on the thermal and structural behavior of composite beams with shear connections subjected to fire conditions. Five partial composite beams with flat, lightweight concrete slabs were designed according to current U.S. codes and standards. Vertical loading was applied to the composite beams, and the surfaces of the steel and concrete were heated using high-temperature ceramic radiant heaters. Variations in the loading and heating protocol provided insight into the mechanical response and failure modes of composite beams and connections. There was an overall reduction in the composite beam load-carrying capacity due to heating, both at elevated temperatures as well as postfire ambient conditions. Concrete compression failure occurred at moderate steel temperatures (350-500°C) combined with overloading. In cases where service level loading was applied, the composite beams and connections sustained the loading and heating up to steel temperatures of 700°C. However, the shear-tab connection fractured during cooling, which highlights the importance of considering both the heating and cooling phases of a fire. [ABSTRACT FROM AUTHOR]

In order to save energy and improve the control of indoor environments, researchers have developed hundreds of computer algorithms that can automatically and continuously analyze the conditions of HVAC systems. However, the complex information requirements of these algorithms inhibit deploying them in real-world facilities. This paper proposes an integrated performance analysis framework that automatically collects, merges, and provides the information required by them. The information items that are used to represent the information needs are categorized, a domain-specific query language that can formally represent the query statements is formalized, and a library of mechanisms that can automatically reason about and retrieve the needed information is developed. In order to validate the performance of the query language and mechanisms, a prototype was also developed, which includes a graphic user interface that helps users to define the queries, and the reasoning mechanisms that process the queries was implemented. [ABSTRACT FROM AUTHOR]

In order to meet the operating requirements during both winter and summer, a thermosyphon heat exchanger unit used to recover energy from the exhaust air needs to be adjusted for its inclination angle by a regulation mechanism. In this paper, the factors that affect the heat transfer efficiency of the thermosyphon heat exchanger was analyzed and the unit practical operating data in a shopping center was studied. The unit optimal operating mode was acquired due to the influence of the unit inclination angle on the temperature effectiveness under a wide temperature change of the outdoor air. In addition, the inclination angle regulation mechanism uses a programmable logic controller (PLC) to control the unit to work at the optimal operating mode. The unit charged with R410A working fluid worked well and was highly effective. [ABSTRACT FROM AUTHOR]

The objective of this paper is to evaluate the healing capacity of steel wool-reinforced porous asphalt concrete. The healing is initiated with induction heating. Bending fracture tests on an elastic foundation are used to prove the healing mechanism. Porous asphalt concrete beams on an elastic foundation were fractured at 5°C; subsequently, they were heated with induction energy, and finally fractured again. The recovered fracture resistance of the beams was used as a healing indicator. Totally fractured porous asphalt beams can regain 78.8% of their bending resistance (strength) when induction heating is applied. It was also found that the optimal heating temperature is 85°C for porous asphalt beams to obtain the highest strength recovery. Reheating of the fractured beams does not decrease the recovery of the flexural resistance, which means that the heating can be repeated when cracks return. On the basis of these findings, it is expected that the healing potential of porous asphalt concrete and the durability of a porous asphalt pavement will be improved by induction heating. [ABSTRACT FROM AUTHOR]

The inelastic nonlinear behaviors of preloaded steel trusses undergoing heating and cooling cycles, a problem not well treated previously, are studied in this paper. A bilinear elastoplastic model with a kinematic strain-hardening rule is adopted for steel at varying temperatures. The material softening effects at elevated temperatures are taken into account via the Eurocode 3 reduction factors. The plastic strain resulting from strain reversal upon unloading at a given temperature is considered in updating the stress-strain curve for the next temperature increment. Two simple trusses are adopted to illustrate the physical phenomena involved. All the equations are presented in incremental form, consistent with the updated Lagrangian formulation. The results for the trusses are believed to be new and can be adopted as the benchmarks for validating other numerical approaches used in treating problems involving the heating and cooling stages. [ABSTRACT FROM AUTHOR]

The complexity of construction industry requires the identification of work tasks and the coordination of interactions among them. As a result, construction planning is considered to be one of the most critical steps toward success and is the main focus of past research. Consequently, little research has been performed regarding the preconstruction planning, which is the planning completed by the contractor in the period between project award and project execution. This paper focuses on sheet metal preconstruction planning, primarily that of mechanical and heating ventilations and air conditioning contractors. The research was completed in three phases: phase one gathered data on the current state of preconstruction planning, phase two developed a model sheet metal preconstruction planning process to be used by sheet metal contractors, and phase three validated the model preconstruction planning process. Based on project data collected for this research, projects that used a planning process similar to the model process performed more successfully—they achieved an average profit margin of 23% while projects that were poorly planned experienced an average profit margin of -3%. [ABSTRACT FROM AUTHOR]

Mechanical characteristics of self-consolidating concretes subjected to elevated temperatures up to 700°C were experimentally investigated in this paper. Eight different concretes [four self-consolidating concretes (SCC) and four conventional concretes (CC)] of different strength categories were produced. At the age of 120 days, specimens were placed in an electrical furnace and the heating was applied at a rate of 5°C/min until the desired temperature was reached. A maximum temperature of 100, 300, 500, and 700°C was maintained for 1 h. Specimens were then allowed to cool in the furnace and tested for compressive strength, splitting tensile strength, and ultrasonic pulse velocity. Similar tests were also performed at room temperature (20°C) for the reference specimens. Residual strength of both SCC and CC was reduced almost similar up to the maximum temperature tested. Explosive spalling occurred in both SCC and CC of the highest strength category at temperatures greater than 380°C. The residual compressive strength of SCC mixtures was higher than the one of CC mixtures for the same strength class. The tentative spalling behavior of SCC and CC was the same and depended only on the strength category. [ABSTRACT FROM AUTHOR]

Experimental investigations were conducted to evaluate the effects of multiple cycles of damage followed by heating repair on the structural properties and fracture toughness of A36, A588, and A7 bridge steels. The test specimens were subjected to multiple cycles of tensile damage followed by compressive restraining stress and heat shortening repair. The damage and repair parameters considered were the damage strain ([variant_greek_epsilon]d), the restraining stress (σr), the number of damage-repair cycles (Nr), and the maximum heating temperature (Tmax). Seventy-five A36, A588, and A7 steel specimens were subjected to multiple damage-repair cycles with Tmax limited to the recommended limit of 650°C. Sixteen additional A36 steel specimens were subjected to multiple damage-repair cycles with Tmax greater than the recommended limit (Tmax=760 or 840°C). Standard material specimens were fabricated from the damaged-repaired steel specimens and tested according to the applicable ASTM standards. The results from the standard material tests indicate that multiple damage-repair cycles have a relatively small influence (±15%) on the elastic modulus, yield stress, and ultimate stress, and a significant influence on the ductility (percent elongation) and fracture toughness of damaged-repaired bridge steels. These effects of the multiple damage-repair cycles on the fundamental structural properties and fracture toughness of various bridge steels are summarized in the paper. [ABSTRACT FROM AUTHOR]

Solar chimneys have been applied widely to various buildings under different climate conditions because of their superiority in improving the indoor environment and saving energy. A series of comparative studies of the performance of solar chimneys used in 12 cities in China under different climatic conditions was carried out. A typical solar chimney in a representative building was studied using numerical simulation and analyzed using orthogonal experiment methods. Results show that the optimal structural configuration and the significance of influencing factors of the solar chimney have strong seasonal consistency. The window-to-wall ratio and wall-to-south wall ratio are the most significant influencing factors. Among the 12 cities, the highest average indoor temperature of the case room could be decreased by 5.7°C in summer and increased by 6.7°C in winter. The cooling and heating loads could be reduced by 30%–100% and 46%–56% respectively. The research results can provide practical guidance for future passive solar technology design. [ABSTRACT FROM AUTHOR]

A new cogeneration system coupled with an absorption heat transformer (AHT) to recover condensed waste heat of a direct-air-cooling coal-fired power plant is presented to reduce the energy grade mismatch between the energy-supplying side and energy-receiving side of the existing waste heat recovery system with an absorption heat pump (AHP). Thermodynamic models of two cogeneration systems, namely, the AHP and heater of the heating network (AHP-HHN) and the absorption heat transformer and heater of the heating network (AHT-HHN), are established. The performance analysis and comparison of two cogeneration systems, focusing on a 600 MW direct air-cooling coal-fired power plant, are carried out from the aspects of energy and exergy utilization. The output power and waste heat recovery ratio are increased by 14.81 MW and 51.56% in the AHT-HHN at 75% THA (turbine heat acceptance) load with a 230,000 kW heating load. The standard coal consumption rate and total exergy loss are decreased by 8.86 g/kWh and 45.54 MW. The total energy efficiency and exergy efficiency are improved by 1.33% and 1.31%, respectively. Moreover, the larger the heating load, the greater the performance difference. The new waste heat recovery scheme can further improve the energy cascade utilization level. [ABSTRACT FROM AUTHOR]

Eight building seismic rubber bearings (four uninsulated lead rubber bearings, one insulated lead rubber bearing, two uninsulated natural rubber bearings, and one insulated natural rubber bearing) were experimentally investigated in fire tests following the ISO834 standard heating process. The effects of vertical load and the duration of fire on the failure mode and residual mechanical properties of the rubber bearings were analyzed. The experimental results show that (1) the fire resistance of rubber bearings without insulation fails to exceed 1.5 h; (2) the duration of fire exposure has significant influence on the mechanical-properties degradation of rubber bearings; (3) the effect of vertical load, to which rubber bearings were subjected during the fire, on the residual mechanical properties and fire resistance is inevident; and (4) the proposed insulation is successful in preventing rubber bearings from significant degradation in mechanical properties in fires. [ABSTRACT FROM AUTHOR]

Shallow geothermal heat exchangers integrated in structural pile foundations have the capability of being an efficient and cost-effective solution to cater for the energy demand for heating and cooling of built structures. However, limited information is available on the effects of temperature on the geothermal energy pile load capacity. This paper discusses a field pile test aimed at assessing the impact of thermomechanical loads on the shaft capacity of a geothermal energy pile. The full-scale in situ geothermal energy pile equipped with ground loops for heating/cooling and multilevel Osterberg cells for static load testing was installed at Monash University, Melbourne, Australia in a sandy profile. Strain gauges, thermistors, and displacement transducers were also installed to study the behavior of the energy pile during the thermal and mechanical loading periods. It has been found that the pile shaft capacity increased after the pile was heated and returned to the initial capacity (i.e., initial conditions) when the pile was allowed to cool naturally. This indicated that no losses in pile shaft capacity were observed after heating and cooling cycles. A variance in average vertical thermal strains was observed along the upper section of the pile shaft at the end of the heating periods. These were almost fully recovered at the end of the cooling periods, indicating that they are of an elastic nature. Pile average circumferential strains were found to be relatively uniform at the end of the heating and cooling periods and did not change with depth. They, also, were fully recovered during the cooling period. It was also observed that the increase of temperature during the heating periods prompted the pile shaft to expand radially. Subsequently, as the pile cooled down, the pile shaft slowly contracted and returned closely to its original condition, suggesting a thermoelastic behavior. [ABSTRACT FROM AUTHOR]

Efficient use of a large quantity of low-grade energy that is available in the earth surrounding a typical residential structure can be realized by designing a HVAC system directly integrating the ground source with a dynamic building envelope. A continuous air duct constructed within the dynamic envelope is configured such that preconditioned air in the basement can be circulated between the shells of the wall. The result is that a large portion of the heat loss through the wall is the geosolar heat extracted from the ground, reducing the load of the home heating system. Air in the ventilation system may also be passed through the heat reservoir such that make-up air is prewarmed and cleaned before entering the interior. This geothermal component of the heating system is further enhanced by increasing the ambient temperature of the earth with unwanted heat absorbed by the roof of the structure during the summer months. The roof of the structure is fitted with narrowly spaced runs of cross-linked polyethylene (PEX) pipe just below the roof surface. Water circulating between these coils and the ground serve to transfer summer heat into the ground while cooling the building. A horizontal blanket of insulation around the perimeter of the building allows heat removed from the roof to be retained for winter use. In addition, cool air from the ground can also be circulated through the dynamic walls during the summer to keep the structure cool. An extensive study involving this integrated building system has been carried out for the last 3 years, and observations of system performance are reported in this paper. [ABSTRACT FROM AUTHOR]

Energy pile, piled foundation incorporating pipe loops for ground source heat pump systems, has been implemented in more and more countries. However, the mechanical performance of energy pile has not been comprehensively studied. To improve the understanding on the performance of energy pile, a field study on energy pile is carried out in this study. A prestressed concrete pipe pile installed with water pipe loops inside was tested as an energy pile in the field. The performance of energy pile during heating and cooling was investigated by using vibrating-wire stress gauges and temperature sensors. The field tests reveal that the temperature influence distance of the energy pile on surrounding soil is approximately 0.5 m from the center of the pile after heating for 60 h. The axial force of energy pile increases/decreases with the increase/decrease of temperature at different rates at different depths. The neutral plane shifts from above 7.7 to below 7.7-m depth because of heating. The magnitudes of shaft resistance increase with temperature increase and decrease with temperature decrease. [ABSTRACT FROM AUTHOR]

Asphalt concrete is a typical self-healing material, and its self-healing rate is influenced by the temperature. Since microwave irradiation is an efficient way of heating, its use could be a novel approach to heating asphalt pavement. In this study, ferrite particles were mixed into asphalt-based composites to upgrade the microwave absorbing efficiency and then further accelerate the self-healing rate of the composites. The microwave-absorbing capability of three kinds of aggregate and three kinds of filler were studied first. It was found that NiZn ferrite has an excellent microwave-absorbing capability under 2.45 GHz compared to other tested materials. Then the heating rate of asphalt mastic, asphalt matrix, and asphaltic concrete mixture with and without NiZn ferrite fillers were tested. The microwave heating rates of these composites all increase significantly with an increase in NiZn ferrite content. Third, the temperature uniformity of asphalt composites was investigated using an infrared thermal imager and a statistical analysis method. It was found that adding adequate amounts of ferrite fillers could notably improve temperature uniformity. Then, through electromagnetic measurement, it was confirmed that the addition of NiZn ferrite particles to mastic confers an excellent microwave-absorbing capability in a frequency range of 1–2.5 GHz compared to plain asphalt mastic. Finally, a fatigue–rest–fatigue test was used to investigate the effect of microwave heating on the self-healing behavior of ferrite-filled asphaltic concrete mixtures. It can be concluded that the healing capability of asphalt concrete can be significantly increased by ferrite particles’ superior microwave absorption properties, leading to the extension of fatigue life. [ABSTRACT FROM AUTHOR]

This study investigates the effect of chemical degradation on the residual mechanical properties of ultrahigh performance fiber-reinforced concrete (UHPFRC) after temperature exposure ranging from 100 to 900°C. Emphasis has been placed on the isolation of chemical degradation. A long drying period and a slow heating rate were used to minimize the buildup of excessive pore pressure caused by water evaporation and transport constraints. To identify critical areas of chemical degradation, differential scanning calorimetry and thermo gravimetric analysis were performed. The results were used in correlation with existing research to aid in deriving a simplified model for predicting the temperature-dependent stress versus strain behavior of UHPFRC. [ABSTRACT FROM AUTHOR]

The experimental results of three full-scale two-story, two-bay, composite steel frames under furnace loading are described briefly. During tests, the composite beams and steel columns were exposed to fire, and only the beam-to-column connections of the tested frames were protected. The furnace temperature, composite steel beam temperature, steel column temperature, horizontal displacements of the columns, and vertical deflections of the composite beams as well as the complete deformation process of the test frames observed during the heating phase and the cooling phase are given. By introducing the slope-deflection equations and joint equilibrium conditions at each joint, the critical temperatures of the buckling of two-story, two-bay, composite steel frames are determined for different furnace scenarios; therefore, this method can consider the effect of the axial force at different levels. The calculated critical temperatures agree well with the experimental results. [ABSTRACT FROM AUTHOR]

Because of their high efficiency and very low emissions, fuel cells have been one of the choice areas of research in current energy development. The solid oxide fuel cell (SOFC) is a type of high-temperature fuel cell. It has the characteristic of a very high operating temperature of 1,027°C (1,300 K). The SOFC has the main advantage of very high performance efficiency (more than 50%) but also has very high exhaust temperatures. Current studies point out that the combination of the SOFC and gas turbine (GT) can produce efficiency of more than 60%. The exhaust temperature of this hybrid power system can be as high as 227-327°C (500-600 K). With this waste heat utilized, it is possible to further improve the overall efficiency of the system. A simulation program of the SOFC/GT system and the introduction of the concept of combined cooling, heating, and power (CCHP) system have been used in this study. The waste heat of the SOFC/GT hybrid power generation system was used as the heat source to drive an absorption refrigeration system (ARS) for cooling. This waste heat enables the SOFC/GT to generate electricity in the system while providing additional cooling and heating capacity. Therefore, the authors have a combined CCHP system developed using three major modules-the SOFC, GT, and ARS modules. The SOFC module was verified by the authors' test data. The GT and SOFC/GT modules were compared with a commercial code and literature data. Both the single- and double-effect ARS modules were verified with available literature results. Finally, the CCHP analysis simulation system, which combines SOFC, GT, and ARS, has been completed. With this CCHP configuration system, the fuel usability of the system by the authors' definition could be more than 100%, especially for the double-effect ARS. This analysis system was demonstrated to be a useful tool for future CCHP designs with SOFC/GT systems. [ABSTRACT FROM AUTHOR]

A constitutive model for rate-dependent and thermomechanically coupled plasticity at finite strains is presented. The plasticity model is based on a J2 model and rate-dependent behavior is included by use of a Perzyna-type formulation. Adiabatic heating effects are handled in a consistent way and not, as is a common assumption, through a constant conversion of the internal work rate into rate of heating. The conversion factor is instead derived from thermodynamic considerations. The stored energy is assumed to be a function of a single internal variable which differs from the effective plastic strain. This allows a thermodynamically consistent formulation to be obtained which, as shown, can be calibrated by use of simple procedures. Choosing 100Cr6 steel in two differently heat treated conditions as prototype material, experimental tests are performed, enabling the model to be calibrated. Significant differences in deformation behavior are noted as the differently heat treated specimens are compared. In addition, the local stress-updating procedure is reduced to a single scalar equation, permitting a very efficient numerical implementation of the model. The constitutive formulation proposed was employed in an explicit finite element solver, illustrative simulations of a high-velocity metal forming process being performed to demonstrate the capabilities of the model and certain characteristic traits of the materials that were studied. [ABSTRACT FROM AUTHOR]

Energy conservation inside the buildings is of utmost importance. To reduce the heating and cooling loads inside the energy-efficient buildings, solar entry regulation as per season can be attained with the use of specific sunshades. Although various static sunshades have been developed depending upon solar geometry, the efficiency with respect to control of solar entry inside the building is a major concern over the seasonal classification for a particular geographic location. The proposed work aims at the design development of a new static sunshade depending on solar angles, whose efficiency has been experimentally verified using a small-scale modeling technique. Three experimental models of insulating material were prepared with varying aspect ratio of windows and static sunshades. Sunlit area, which in turn controls the temperature inside the models, has been made the criteria for deciding the effectiveness of the proposed sunshade over existing horizontal sunshade. The proposed technique can be applied at any geographic location over the world for which sunshade can be designed as per the climatic requirements of the place. [ABSTRACT FROM AUTHOR]

This research investigated the efficacy of low-intensity, radiant, infrared heating for inducing thawing in frozen ground. Specifically, the performance characteristics of a 22 kW infrared tube heater were evaluated. A commercial building site in Park City, Utah, was instrumented with thermocouple piers for field testing over a period of approximately 5 days. The experimental data were used to calibrate a numerical model of the infrared heating process, and several numerical simulations were then performed. The simulations facilitated evaluation of the effects of radiation intensity, air temperature, and ice content on thaw penetration rates achieved using infrared heating. While ice content has a marked influence on thaw penetration rates in all the simulations, the air temperature becomes less important with increasing infrared radiation intensity. The results of the testing also indicate that the tube heater exhibits a steady reduction in emitted radiation between propane tank exchanges and that the heaters should be used in tandem to minimize spatial variations in radiation intensity. Further research is recommended to identify optimal applications of infrared heating in winter construction activities. [ABSTRACT FROM AUTHOR]

Currently, the design of reinforced concrete (RC) columns is essentially based on tabulated data. A more scientific approach based on an understanding of the fundamental behavior of columns in fire is useful to structural engineers. Tan and Yao in 2003 developed a simple and rational design method to predict the fire resistance of 4-face heated RC columns. The predictions of the proposed method agree well with test results. The same method can be extended to 1-, 2-, and 3-face heated columns with some modifications. The effects of elevated temperature on material deterioration with regard to the strength and stability of columns are quantified. Furthermore, the shift of neutral axis due to nonsymmetric heating is predicted in the proposed method. For columns under 1- or 3-face heating, only uniaxial bending needs to be considered, but for 2-face heating, the effect of biaxial bending is taken into account. A finite element code SAFIR, developed at the University of Liege, Belgium, was used to benchmark the proposed simplified calculation method. [ABSTRACT FROM AUTHOR]

As concrete deteriorates, rehabilitation work on construction elements is often needed. One of several techniques that restores, or even increases, the initial resistance of the element, is the bonding of steel plates to the original concrete element. In general, the new element behaves well under normal load conditions. However, the bonding agent may deteriorate when subjected to temperature increase, and failure may ensue. The present work reports laboratory tests that aim to analyze the influence of the geometry of the bonding on the shear resistance of the connection. The results are presented for different temperatures, two types of concrete and several bonding geometries. [ABSTRACT FROM AUTHOR]

This study evaluates the economic feasibility as well as the effect of window modifications on the heating and cooling energy requirement of the Canadian housing stock based on detailed energy simulations conducted using the Canadian hybrid residential end-use energy model (CHREM) and green house gas emissions model (GEM). It is found that thermally improved windows can substantially reduce the energy consumption and greenhouse gas emissions from the Canadian residential sector. The magnitude of energy consumption and greenhouse gas (GHG) reductions depend largely on the size of the housing stock, existing window type characteristics, climate, and fuel mix used. Thus, there are variations from province to province. Similarly, economic feasibility depends on the magnitude of savings available as well as the price of energy in each province. [ABSTRACT FROM AUTHOR]