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RISS 인기검색어
- 검색키워드
- 저자 : Pirmohammad, Sadjad (검색결과 4 건)
- 무료
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Impact of temperature cycling on fracture resistance of asphalt concretes
Sadjad Pirmohammad,Ahad Kiani 사단법인 한국계산역학회 2016 Computers and Concrete, An International Journal Vol.17 No.4
Asphalt pavements are exposed to complex weather conditions and vehicle traffic loads leading to crack initiation and crack propagation in asphalt pavements. This paper presents the impact of weather conditions on fracture toughness of an asphalt concrete, prevalently employed in Ardabil road networks, under tensile (mode I) and shear (mode II) loading. An improved semi-circular bend (SCB) specimen was employed to carry out the fracture experiments. These experiments were performed in two different weather conditions namely fixed and cyclic temperatures. The results showed that consideration of the impact of temperature cycling resulted in decreasing the fracture toughness of asphalt concrete significantly. Furthermore, the fracture toughness was highly affected by loading mode for the both fixed and cyclic temperature conditions studied in this paper. In addition, it was found that the MTS criterion correctly predicts the onset of fracture initiation although this prediction was slightly conservative.
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Temperature effects on brittle fracture in cracked asphalt concretes
Ayatollahi, Majid-Reza,Pirmohammad, Sadjad Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.45 No.1
Cracking at low temperatures is one of the frequently observed modes of failure in asphalt concretes. In this investigation, fracture tests were performed on cracked asphalt concrete subjected to pure mode I and pure mode II loading at different subzero temperatures. An improved semi-circular bend (SCB) specimen containing a vertical crack was used to conduct the experiments. The SCB specimens produced from the gyratory compacted cylindrical samples were compressively loaded, and critical stress intensity factors, $K_{If}$ and $K_{IIf}$, were then calculated using peak loads obtained from the tests. The experimental results showed that with decreasing the temperature, mode I and mode II critical stress intensity factors increased first but below a certain temperature they both decreased. It was also found that at a fixed temperature, the mode II fracture resistance of the asphalt concrete was higher than its mode I fracture resistance.
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Temperature effects on brittle fracture in cracked asphalt concretes
Majid-Reza Ayatollahi,Sadjad Pirmohammad 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.45 No.1
Cracking at low temperatures is one of the frequently observed modes of failure in asphalt concretes. In this investigation, fracture tests were performed on cracked asphalt concrete subjected to pure mode I and pure mode II loading at different subzero temperatures. An improved semi-circular bend (SCB)specimen containing a vertical crack was used to conduct the experiments. The SCB specimens produced from the gyratory compacted cylindrical samples were compressively loaded, and critical stress intensity factors, KIfand KIIf, were then calculated using peak loads obtained from the tests. The experimental results showed that with decreasing the temperature, mode I and mode II critical stress intensity factors increased first but below a certain temperature they both decreased. It was also found that at a fixed temperature, the mode II fracture resistance of the asphalt concrete was higher than its mode I fracture resistance.
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Three-dimensional finite element modeling of a transverse top-down crack in asphalt concrete
Majid R. Ayatollahi,Sadjad Pirmohammad,Karo Sedighiani 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.13 No.4
In this paper, a four-layer road structure consisting of an edge transverse crack is simulated using three-dimensional finite element method in order to capture the influence of a single-axle wheel load on the crack propagation through the asphalt concrete layer. Different positions of the vehicular load relative to the cracked area are considered in the analyses. Linear elastic fracture mechanics (LEFM) is used for investigating the effect of the traffic load on the behavior of a crack propagating within the asphalt concrete. The results obtained show that the crack front experiences all three modes of deformation i.e., mode I, mode II and mode III, and the corresponding stress intensity factors are highly affected by the crack geometry and the vehicle position. The results also show that for many loading situations, the contribution of shear deformation (due to mode II and mode III loading) is considerable.
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