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The existence of rutting or permanent deformation on flexible pavement layers has always been a concern that negatively affects the performance of roads by reducing the lifespan of pavement structure and by posing a safety risk for vehicles over the road. Traffic overloading is one of the primary factors that accelerates the deterioration of flexib...
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Context 1
... main benefit of using survival analysis is that it can better deal with censored data which represents the incomplete observed responses during the observation phase (SAS institute, 2004). Fig.1 represents the three different types of censored data used to determine the time of failure of flexible pavement. ...
Context 2
... main benefit of using survival analysis is that it can better deal with censored data which represents the incomplete observed responses during the observation phase (SAS institute, 2004). Fig.1 represents the three different types of censored data used to determine the time of failure of flexible pavement. ...
Citations
... This master curve allows researchers and engineers to assess how a material will behave under different loading conditions and temperatures, providing valuable information for material selection and structural design [48,49]. Also, the dynamic modulus is an essential parameter in predicting the performance of materials in various applications [44,50]. The construction of the master curve involves shifting, using the time-temperature superposition principle (TTSP), different measurements of dynamic modulus to a reference temperature ( T ref ) and subsequently fitting of the data to a sigmoidal model expressed by Eq. (1) [47]. ...
Warm mix asphalt (WMA) is recognized for its eco-friendly attributes minimizing energy consumption and emissions during production and application of asphalt concrete (AC). Yet, a comprehensive assessment of the performance of each WMA technology in the long term is pivotal to validate its role in advancing sustainability and infrastructure resilience. Most of the previous studies investigated the effect of aging on hot mix asphalt (HMA) and WMA mixtures by assessing the properties of extracted original and WMA binders. Hence, there is a necessity for mechanistic evaluation and practical comparison of the performance of aged AC using each WMA technology against HMA at the mixture level through linear viscoelastic characterization, while taking into account local materials. This is conducted in this study by measuring the dynamic modulus and phase angle of short- and long-term aged HMA and chemical WMA samples across a spectrum of temperatures and loading frequencies. Additionally, the flow number (FN) and the simple performance indicators were computed to further evaluate the mixtures’ susceptibility to rutting and fatigue distresses. The results suggested that the use of chemical additive in WMA improved the mixture’s resistance to aging. Additionally, the findings of the statistical analysis revealed a significant increase in the dynamic modulus of both chemical WMA and HMA mixtures over the long term. Notably, chemical WMA exhibited generally smaller dynamic modulus and higher phase angle values than HMA under various temperature and frequency conditions during both aging scenarios. This implies that chemical WMA exhibits decreased rutting resistance, remaining within acceptable levels with FN values above 190 cycles, while enhancing fatigue resistance and subsequently improving durability in both short and long-term scenarios.
... Rutting is also one of the typical failure modes of semi-rigid base asphalt pavement in the high-temperature area [20]. The presence of rutting on flexible pavement structure has always been a concern that destructively influences the performance of the pavement by shortening its lifespan and creating a safety hazard for vehicles [21]. Permanent deformation can also incline to severe traffic accidents under some adverse driving circumstances such as rain and curve section [22]. ...
This research investigated the largest magnitude of displacement and horizontal tensile strain in several critical locations within the asphalt concrete (AC) layer in both the flexible pavement highway (FPH) and asphaltic overlayment track (AOT) structure using the numerical modeling method. The role of the hauling loads, speed, and loading cycles of freight truck’s dumps and freight train’s wagons on the mechanical behavior of FPH and AOT in terms of the permanent deformation and fatigue cracking was examined. Furthermore, the performance of the FPH and AOT in terms of permanent deformation and fatigue cracking characteristics due to various magnitudes of hauling loads, speed, and loading cycles of freight truck’s dumps and freight train’s wagons was compared to determine the optimum infrastructure for the freight coal transportation, based on the hauling capacity as well as the magnitude of permanent deformation and the horizontal tensile strain of the AC layer. According to the findings of this study, it is suggested to choose the AOT structure with fourth or sixth loading systems to run the freight coal transportation with the highest magnitude of the hauling capacity of 360,000 tons, since it produces the minimum magnitude of the permanent deformation and fatigue cracking of the AC layer. Future research should be conducted to examine the potential and the characteristics of fatigue cracking due to the contact between the edge of the sleeper and the surface of the AC layer in AOT.
... However, these beams rarely undergo design or structural modifications, despite their extensive history of use. Standard verifications of these structures have unveiled the inefficient utilization of traditional I-beams alone (Hosseinpour et al., 2018;Ranzi et al., 2013). ...
Various types of structures can be constructed using reinforced concrete, including slabs, walls, beams, columns, foundations, frames, and more. The incorporation of structural steel and reinforcements in concrete enhances the strength and durability of structural elements while compensating for the tensile weaknesses in the concrete material. This study aimed to investigate the behavior of reinforced concrete beams utilizing structural steel of different shapes. Four types of concrete beams were prepared: a standard beam with normal reinforcement, and three composite beams, each featuring structural steel with different sectional shapes-T-section, I-section, and channel section. The consistent parameters included the cross-sectional area of the specimens, each measuring 100x150x450 mm, a steel reinforcement percentage of 2% of the total volume, and the compressive strength of the concrete. The conducted tests involved applying a concentrated load at the mid-span of each beam to examine the specimens' behavior in terms of strength, flexural load capacity, deflection, crack patterns, and failure mode. The results of this study reveal that, given the same steel ratio, the load capacity of beams reinforced with structural steel of a channel shape has surpassed that of the other beams. Additionally, specimens with structural steel plates exhibited higher maximum deflections before failure compared to the beams with conventional reinforcement.
... Several studies have utilized the LTPP data to develop engineering products that are useful in construction, maintenance, pavement management, and design. Hatoum et al. 2022a conducted a survival analysis to predict asphalt pavement performance and assess the influence of various factors extracted from LTPP on fatigue cracking (Hatoum et al. 2022a) and pavement rutting (Hatoum et al. 2022b). ...
This paper focuses on conducting a comparative study between mechanistic empirical (NCHRP1-37A) design method and empirical 1993 AASHTO design method. The flexible pavement sections selected for the study are from different regions in the United States with varying climatic conditions. The typical data required for defining and characterizing the pavement structure were gathered from FHWA's Long-Term Pavement Performance (LTPP) program. The pavement sections are initially designed using 1993 AASHTO design method at various conditions including different traffic levels, percentage of overloaded vehicles, and environmental conditions. Both default and available local calibration models for the selected regions are used to predict the performance of flexible pavement by mechanistic empirical pavement design guide (MEPDG) software. The results reveal that despite selecting the same serviceability loss in designing flexible pavement using 1993 AASHTO empirical method, the obtained results showed a noticeable variation in the predicted pavement performance while analyzing these sections using MEPDG design approach. The computed performance of AASHTO designed pavements using local and default calibration models are significantly different. Furthermore, as the percentage of overloaded trucks increases, pavement distresses computed at the end of the service life exceed the permissible distress limit in most cases. For pavements located in regions with higher average temperatures, the pavement performance exhibits the least total rutting performance. Finally, the worst pavement performance for alligator cracking distresses is observed for pavement sections designed with a strong subgrade for moderate and high traffic volume in warm climates.
