Wheel abnormality intensifies impact characteristics of train loads on railway concrete ties. Concrete ties are commonly prestressed with single or multiple tendons. This paper presents experimental studies on crack propagation of prestressed concrete ties with single steel tendons subjected to impact loads. The presented study includes the effect of supplementary fiber reinforcement using polypropylene fibers on crack arrest, in terms of fiber type and content by volume. Concrete ties are modeled as flexural beams subject to four-point loading system. A mass dropped from predetermined height simulated the wheel impact loads. Experimental results include crack patterns, dimensions, and accompanied loads. The concrete beams reinforced with fibers experienced a delay in crack growth in both length and width. Further, the fiber reinforced beams had smaller initial crack length in comparison to beams with no fiber reinforcement.
Cite this paper: Fariborz M. Tehrani, Rosa M. Serrano, Crack Propagation of Concrete Beams Prestressed with Single Strand Tendons, Journal of Civil Engineering Research, Vol. 4 No. 3, 2014, pp. 71-81. doi: 10.5923/j.jce.20140403.03.
Landslide can be defined as the mass movement of rock, debris or earth down a slope [1,2,3]. It is currently one of the most common natural disasters in the world. Landslide causes and triggers have attracted the attention of researchers for centuries, most especially as early warning and mitigation measures. The causes of landslide are those factors that rendered slopes vulnerable to failure, while triggers are factors that initiate the downslope movement or slide. The major triggering factors include both natural and human activities . The natural triggering factors include precipitation and slope instability, while landslides that are entirely due to or aided by human activities such as construction, mining, quarrying and excavations remain on the increase all over the world [4,5,6,7]. Slow and steady decrease in rock strength due to fracturing, water infiltration into cracks and pore spaces, weathering, etc., are some of the causes. The record of Fatal Landslides in America between 2002 and 2007  and between 2004 and 2016  exceeds forty thousand occurrences. The high incidence of fatal landslides may be accredited to an increase in water level due to global warming and climate change [10, 11], deforestation due to development and urbanization, etc.
The landslide in Agboona Hill, probably initiated with the development of parallel normal faults along the horst, further weakening of this zone by fracturing, water infiltration and gravity led to shattering of rocks along this zone. However, numerous open fractures joints, cracks, folds and high strain shears were encountered on the ruptured surfaces. Borehole and geophysical data that can help to verify the influence of earthquake were not available at the time of compiling this manuscript. However, most of the rock fragments displaced by the landslide show well-polished surfaces, suggesting that the dominant processes along this fault zone are bulk crushing, surface grinding and polishing.
Relic plumose structure preserved on the fracture surface (Fig. 4) shows a feathery Mode 1 (one) joint surface with E-W propagation direction. This is interpreted as the intermediate stress axis δ2. This structure reveals the direction of joint propagation to be E-W, and it was produced due to the changing intensity of the stress field at the tip during the growth of the joint. The stress intensity is proportional to the length of the crack. The Plumose structure is formed when an unexposed joint surface revealed a rough pattern resembling the imprint of a feather. The stress intensity is proportional to the length of the crack. 1e1e36bf2d