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Steel Buildings
Published in Bungale S. Taranath, Tall Building Design, 2016
Plug welds and slot welds are used to transmit shear in lap joints and to prevent buckling of lapped parts. In buildings, they also may be used to join components of built-up members. (Plug and slot welds, however, are not permitted on A514 steel.) The welds are made, with lapped parts in contact, by depositing weld metal in circular or slotted holes in one part. The openings may be partly or completely filled, depending on their depth. Load capacity of a plug or slot completely welded equals the product of hole area and allowable stress. Unless appearance is a main consideration, a fillet weld in holes or slots is preferable.
Effect of subgrade on piezoelectric energy harvesting under traffic loads
Published in International Journal of Pavement Engineering, 2018
Guangya Ding, Xiaoxia Zhao, Fan Sun, Jun Wang
Of the studies undertaken to investigate the couplings of pavements and piezoelectric transducers, Erturk (2011) derived the instantaneous electrical response of surface patches to moving loads. They discussed two-dimensional surface strain fluctuation of the large structure which formed the local way of piezoelectric energy collection. In comparison with different piezoelectric transducers employed by Zhao et al. (2012), multilayer piezoelectric ceramics can have high efficiency. However, the high stiffness of piezoelectric ceramics may limit the gain of more vibration energy. Peigney and Siegert (2013) used cantilever piezoelectric devices to investigate the energy harvesting caused by bridge traffic. Even if the bridge vibration is small amplitude and low frequency, the average power of 0.03 mW can be generated. The voltage is between 1.8 and 3.6 V. Faisal et al. (2016) developed a rectangular composite plate piezoelectric device with A514 steel as the basement layer to collect the vibration energy generated by the road vehicles. It was also possible to optimise the parameters of the piezoelectric device by numerical simulation. Chen et al. (2016) investigated the effectiveness of embedded piezoelectric elements from the asphalt pavement and developed a compression model to evaluate the efficiency of the piezoelectric device. They indicated that the output power depends on the loading cycle, the position and the size of the piezoelectric device. Roshani et al. (2016) measured the piezoelectric plate output power under different numbers and arrangements through uniaxial compression tests. The influence of temperature on the output power may be negligible, but the amplitude and load time will significantly affect the output power. Further, they (2017) also observed that piezoelectric stack connected in parallel can produce higher current output under similar loading conditions. The above studies only consider the influence of the road surface layer on piezoelectric transducers, and does not take into account the influence of the roadbed on the performance of piezoelectric transducers.