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Kinetics of Particles
Published in M Rashad Islam, A K M Monayem H Mazumder, Mahbub Ahmed, Engineering Dynamics, 2022
M Rashad Islam, A K M Monayem H Mazumder, Mahbub Ahmed
An impact is a high force or shock applied over a short period when two or more bodies collide. Such a force or acceleration usually has a greater effect than a lower force applied over a proportionally longer period. The effect depends, critically, on the relative velocity of the bodies to one another. For example, a nail is pounded with a series of impacts, each by a single hammer blow. These high-velocity impacts overcome the static friction between the nail and the substrate. Although on a much larger scale, a pile driver achieves the same result by driving a pile into the soil. This method is commonly used during civil construction projects to make the foundations for buildings and bridges. Road traffic accidents usually involve impact loading, such as when a car hits a traffic bollard, water hydrant, or tree, the damage is being localized to the impact zone. If the force that the objects exert on each other is parallel to the path of motion and directed toward the center of gravity of each object, the objects undergo a direct central impact. Otherwise, it is called oblique central impact.
Preliminary Engineering
Published in Connie Kelly Tang, Lei Zhang, Principles and Practices of Transportation Planning and Engineering, 2021
Piers and bents may be comprised of multiple piles. Piles can be constructed with precast piles driven into the ground by a pile driver. Piles can also be constructed with concrete poured into drilled shafts (boreholes drilled into the ground) to form in-situ piles in the field. In addition, piers can be formed from walls or columns resting on a spread footing. Piles and spread footing transfer bridge loads onto surrounding soil and bedrock to gain stability.
Numerical analysis of rehabilitated concrete pavement using crack-and-seating technique
Published in International Journal of Pavement Engineering, 2021
Li Liu, Shenghua Wu, Wenkai Xie, Gang Yao
The crack-and-seating technique, also called break-and-seat, is widely used due to the belief that the load transfer between the slablets of concrete is still partially preserved and reflection cracking can be effectively mitigated (Ceylan et al. 2005, Khazanovich et al. 2012). The introduced cracking is accomplished by a large construction equipment such as pile driver or hammer, which raises heavy weight above the pavement surface and drop it to fracture the concrete slab (Ceylan et al. 2005). Many practices have also demonstrated the benefit of using crack-and-seating technique such as in Illinois (Schutzbach 1989) and Virginia (Freeman 2002) of United States.