Showing 37–48 of 670 results
Environmental, Economic, and Social Implications of Highway Concrete Rehabilitation Alternatives
Currently, there isرایگان!
Currently, there is no comprehensive benchmark of life-cycle assessment for the rigid pavement alternatives for highway rehabilitation. To fill this gap, the major objective of this study is to investigate the environmental, economic, and social impacts of the three most widely adopted rigid pavement choices through a life-cycle assessment approach with custom-built economic input-output life-cycle assessment (EIO-LCA) models. Quantity takeoffs were performed for each alternative assuming a 1-lane-km highway rehabilitation. Subsequently, the construction costs of each alternative were computed in order to determine the present values for a life span of 50 years, while at the same time accounting for a different life expectancy for each pavement rehabilitation strategy. The present values were then incorporated into a corresponding EIO-LCA model. The results clearly indicate that continuously reinforced concrete pavement (CRCP) is the most sustainable choice and much preferable to the other alternatives for minimizing negative environmental, economic and social impacts from the life-cycle perspective. This finding champions a wider adoption of CRCP for future sustainable transportation infrastructure development projects, as CRCP’s relatively high initial construction cost can be recouped by long-term sustained benefits. The results and findings of this study can serve as a solid foundation for industry practitioners and decision-makers to make better-informed project decisions when choosing the most sustainable pavement alternatives from a life-cycle perspective. DOI: 10.1061/(ASCE)CO.1943-7862.0001063. © 2015 American Society of Civil Engineers.
Evaluation of Base Shear Absorption of Combined System; RC Frame & Precast 3d Panels with Irregularities in Vertical
The current study inرایگان!
The current study investigates the base shear absorption of combined systems, RC frame pre-cast 3D wall sandwich panels in both linear and non-linear material properties. The seismic behavior of building constructed by 3D panels is studied using numerical approach finite element method. The obtained results are compared with regular bending RC frames, complete box type sandwich wall panels system, and present the differences of behavior and absorbance in each system and also the variation of vertical stiffness on structural response is examined. The material nonlinearities simulated with drucker-prager and von-misses failure criteria. The validation of FEM analysis is test with those obtained through experimental
Evaluation of Horizontal Seismic Hazard of ABADE, Iran
This paper presentsرایگان!
This paper presents probabilistic horizontal seismic hazard assessment of Abade, Iran. It displays the probabilistic estimate of Peak Ground Horizontal Acceleration (PGHA) for the return period of 475 and 2475 years. The output of the probabilistic seismic hazard analysis is based on peak ground acceleration (PGA), which is the most common criterion in designing of buildings. A catalogue of seismic events that includes both historical and instrumental events was developed and covering the period from 840 to 2007 is used. he seismic sources that affect the hazard in Abade were identified within the radius of 150 km and the recurrence relationships of these sources were generated by Kijko and Sellevoll . Finally four maps have been prepared to indicate the earthquake hazard of Abade in the form of iso-acceleration contour lines for different hazard levels by using SEISRISK III
Experimental Investigation of Time-Dependent Effect on Shear Strength Parameters of Sand–Geotextile Interface
The time-dependent bرایگان!
The time-dependent behavior of soils has been investigated extensively using one-dimensional and triaxial tests. The phenomena associated with time effects in soils are creep, relaxation, strain rate and rearrangement effects. The engineering properties of soil are often improved significantly with the time elapse. The objective of this paper is to investigate the time-dependent effect on the shear strength parameters of sand–geosynthetic interface using large direct shear test apparatus. For this purpose, the geotextile layer has been adhered gently on a piece of wood with a thickness such that a half of the shear test box has been occupied. The other half of the box has been filled with the sand and the test has been performed. Three normal stresses of 30, 45, and 60 kPa have been applied in all tests. The shear stress has subsequently been applied in different times to the failure stage. In all tests, the shearing velocity has been kept the same. The results of these experiments show that the stiffness and friction angle of the dry sand– geotextile interface increases up to 12.6% and 3.9% at 720 minutes after the sample is poured in the mold
Exploiting Home Automation Protocols for Load Monitoring in Smart Buildings
Monitoring and contrرایگان!
Monitoring and controlling electrical loads is crucial for demand-side energy management in smart grids. Home automation (HA) protocols, such as X10 and Insteon, have provided programmatic load control for many years, and are being widely deployed in early smart grid field trials. While HA protocols include basic monitoring functions, extreme bandwidth limitations (<180bps) have prevented their use in load monitoring. In this paper, we highlight challenges in designing AutoMeter, a system for exploiting HA for accurate load monitoring at scale. We quantify Insteon’s limitations to query device status—once every 10 seconds to achieve less than 5% loss rate—and then evaluate techniques to disaggregate coarse HA data from fine- grained building-wide power data. In particular, our techniques learn switched load power using on-off-dim events, and tag fine-grained building-wide power data using readings from plug meters every 5 minutes.
Exploiting Home Automation Protocols for Load Monitoring in Smart Buildings
Monitoring and contrرایگان!
Monitoring and controlling electrical loads is crucial for demand-side energy management in smart grids. Home automation (HA) protocols, such as X10 and Insteon, have provided programmatic load control for many years, and are being widely deployed in early smart grid field trials. While HA protocols include basic monitoring functions, extreme bandwidth limitations (<180bps) have prevented their use in load monitoring. In this paper, we highlight challenges in designing AutoMeter, a system for exploiting HA for accurate load monitoring at scale. We quantify Insteon’s limitations to query device status—once every 10 seconds to achieve less than 5% loss rate—and then evaluate techniques to disaggregate coarse HA data from fine- grained building-wide power data. In particular, our techniques learn switched load power using on-off-dim events, and tag fine-grained building-wide power data using readings from plug meters every 5 minutes .
Fading and color changes in colored asphalt quantified by the image analysis method
Colored asphalt paveرایگان!
Colored asphalt pavement can create better visual setting as well as improve the safety and smoothness of driving. In this research, colored asphalt samples with various amounts of dye are examined to study the surface color changes at different aging periods. Distributions of surface colors on the samples are analyzed in both the RGB and HSI color spaces. Two types of dyes, green and red, with five different ratios are mixed with clear asphalt to make colored asphalt samples. The samples are exposed to ultraviolet light in the QUV tester for five different aging spans. Results show that the amount and type of dye added, and the different aging spans affect fading in the colored asphalt. Results also indicate that clear asphalt mixed with 5% or more of dye is capable of manufacturing better-colored asphalt. Finally, colored asphalt with red dye showed better resistance to ultraviolet light.
FFECTS OF SOIL-STRUCTURE INTERACTION AND BASE ISOLATION ON SEISMIC PERFORMANCE OF FOUNDATION SOILS
This study primarilyرایگان!
This study primarily focuses on structural induced liquefaction potential. Moreover, the effect of base isolation systems on both structural performance and liquefaction potential was studied including the soil-structure interaction effects. Four different types of structures and three different types of local sites were analyzed under two different input ground motions. It was mainly found that, depending on the structural type and for a certain depth, the liquefaction potential could be higher under the structure than the one in the free field. Besides decreasing the story drifts and shear forces in the structure, base isolation systems were very effective for decreasing liquefaction potential in the soil. It was also observed that soil-structure interaction leads to very significant changes in the response spectra.
Flexibility based method for the extent of damage in degrading bridge structures after in-service loading
This paper presents ...رایگان!
This paper presents a method to identify damage in bridge structures based on the flexibility matrices in the modal strain space. In the tudy by the Ritz vectors extracted from flexibility matrix, the damage is identified. The localization approach is applied to low levels of damage on the prestressed concrete girder of simply supported bridge, with a focus on using a small number of sensors and only the fundamental mode of vibration. The validity of the method is also demonstrated using experimental modal data of a plate girder from I-40 Bridge over the Rio Grande. The predictions were found to closely match the actual response of the bridges. The proposed method can detect the damage in bridge structures using a limited number of sensors and vibration modes
Foundation size effect on modulus of sub grade reaction on Sandy soils
Winkler model is one...رایگان!
Winkler model is one of the most popular models in determining the modulus of sub grade reaction. In this model, the sub grade soil is assumed to behave like infinite number of linear elastic springs. The stiffness of these springs is named as the modulus of sub grade reaction. This modulus is dependant to some parameters like soil type, size, shape, depth and type of foundation. The direct method for estimating the modulus of sub grade reaction is plate load test that is done with 30-100 cm diameter circular plate or equivalent rectangular plate. Afterward, we have to extrapolate the test value for exact foundation. In the practical design procedure, Terzaghi’s equation is usually used to determine the modulus of sub grade reaction for exact foundation, but there are some uncertainties in utilizing such equation. In this paper the size effect of foundation on sandy sub grade with use of finite element software (Plaxis 8.2) is proposed to investigate the validation of Terzaghi’s formula on determination of sub grade reaction modulus. Also the comparison between Vesic’s equation, Terzaghi’s one and obtained results are presented
Geomorphologic hazards for Vanyar Dam with emphasis on the reactivation of Tabriz fault, northwest Iran
Shahid Madani or Vanرایگان!
Shahid Madani or Vanyar Dam is being construction on Aji Cahy River, to the north of Tabriz. It has been built on the upper red formation of Miocene. This lithology generally consists of sandstones, conglomerates, clays, and gypsum. Salt domes are also located underneath the reservoir area behind the dam. The slopes beside the reservoir are not stable. Unexpected events, such as subsidence, could occur after the reservoir is filled causing destruction to infrastructure. However, the most serious event could be the infiltration of water into the Tabriz fault. This fault has not been reactivated for over 220 years and it is thought that the infiltration of water from the reservoir could cause the two sides of the fault plane to move. It is thought that the displacement of the fault could cause an earthquake of more than 6.5 on the Richter scale. To try and prevent this fault reactivating, filling of reservoir is proposed to be undertaken gradually.
Hardening of clayey soil blocks during freezing and thawing cycles
Considering the lackرایگان!
Considering the lack of references dealing with the behaviour of clayey soil blocks subjected to freezing– thawing cycles, exploratory work has been carried out on such blocks to study the effects of freezing– thawing cycles on their mechanical properties. As the blocks were not stabilized, the procedures conventionally applied for freezing–thawing cycles, in which the samples are immersed, were adapted to this case of study: the specimens were humidified by placing them in a moist environment for 1 week (20 °C and 95% RH (relative humidity)) and were then subjected to freezing–thawing cycles without any re- humidification between cycles. The variations of weight and compressive wave velocity showed that freezing–thawing cycles led to the desiccation of the samples. The consequences of these cycles on the characteristics of the soil blocks were thus those of a conventional desiccation of specimens and, in particular, their hardening. This hardening was highlighted by the study of the mechanical characteristics of the clayey soil blocks (compressive strength and modulus).