No abstract

Experimental investigations on the mechanical responses of fully clamped circular plates with prefabricated crack at room temperature and low temperature have been conducted. Initial cracks with different lengths were prefabricated by the electrical discharge machining method. Low ambient temperature was created by the liquid nitrogen in a low-temperature chamber, and a dropping hammer was dropped from the same height with a constant impact energy of 5 J to carry out the repeated impact. Experimental test results show that the prefabricated crack has a significant influence on the mechanical behavior of the thin plates. The maximum impact force decreases with increase of the crack length, and the threshold impact number until fracture decreases with increase of the crack length. It is also observed from the test results that the maximum impact force increases with decrease of the temperature, while threshold impact number until fracture and the plastic permanent deformation decreases due to the brittleness of the material in low temperature. The present investigations provide useful insight into the failure mechanism of the clamped thin plate with initial crack under low-velocity repeated impacts in low temperature, which will lead to a guideline for research and design of marine structures in the arctic area.

We usually calculate the fatigue damage by superimposed respective injury; the paper brings up the superimposed load spectrum method considering load sequence. It superimposed on the load spectrum of each load and obtained the total damage of total stress time history. Finally, as an example, bolster’s damage is calculated by two ways. By contrast, the damage is larger by former method. The injury results based on the method of superimposed load spectrum is closer to the actual situation. Therefore, the research method presented in this paper can provide a reference for future structural damage.

It is used as an example that the composite foundation with long-short-piles is used in liquefied soil under a high-rise building .By using the finite element method, the effects of short pile replacement ratio, long pile replacement ratio, raft thickness on side friction of the pile are discussed respectively. The results show that: Short pile replacement ratio changes have an effect on side friction of the long pile from 4m to 15m. With long pile replacement ratio increasing, negative friction and positive friction of the long pile decreases gradually. With the raft thickness increasing, negative friction and positive friction of the long pile decreases gradually. Otherwise, the distance of side friction of the long pile comes up to zero increase gradually. These conclusions are provided as references for future optimum design.