جستجوی مقالات مرتبط با کلیدواژه "wharf" در نشریات گروه "عمران"

Wharf is an engineering structure which is constructed generally for loading or unloading of goods. The structure may be constructed on the weak layers like gravel and sand with respect to the bank conditions. In case of incorrect design of this type of structure and its failure, the wharf activities may be stopped for a long time due to damage to adjacent facilities. For this reason, investigating the behavior of coastal structures against failure factors such as earthquake and the liquefaction due to it, is of great importance. Analysis of wharf performance against liquefaction is done generally using the numerical methods. In this article using the Flac2D software which has the capability of nonlinear analysis of effective stress and generation of excess pore water pressure in the soil continuum, the liquefaction phenomenon in the soil surrounding the wharf is simulated using the behavioral model Finn. In continuation, the impact of different earthquake parameters on the wharf behavior is investigated. Finally, the results of the excess pore water pressure, horizontal displacement, soil settlement and bending moment of piles are presented. Then, the correlation between these parameters and different earthquake parameters is investigated. As the earthquake intensity criteria have great importance in terms of statistical assessment of seismic demand of various types of structures, therefore, in this study in order to investigate the quality of earthquake intensity criteria, the determining indices such as being optimal and applicable, efficiency index, sufficiency with respect to the earthquake magnitude and distance to the center of earthquake propagation are investigated. The results show that compatibility between the earthquake parameters and soil settlement is generally better with respect to other parameters.

The coastal structures such as wharves withstand severe operational conditions during their service life; hence, they are susceptible to damage and reduction in the stiffness of their elements. In this paper, the performance of a damage detection method based on power spectral density is numerically investigated on the dolphin platform of the oil wharf used for the unloading of crude oil to the refinery. This investigation is held numerically, and the damage is modeled as a percent reduction in stiffness of the elements. For this purpose, the finite-element model of the dolphin is made in the MATLAB software and the effect of surrounding water is considered as the added mass on the elements. To probe the performance of the method on the dolphin model, several assumed damage scenarios with different levels of damage in the structure, are considered. Furthermore, an approach for calculation of the spectral density of excitation using an approximate FRF is introduced. Results prove the success of the method in the identification of the parameters of a stiff coastal structure like a dolphin. Besides, the results from these investigations prove that the added mass significantly affects the damage detection results. The quality and accuracy of the numerical results prove the merits of damage detection by finite-element model updating in the frequency domain. The results of the present study urge the practical assessment of the performance of the method in the future.

During the past decades, there has been an ever increasing demand for construction of new wharves and port facilities in Iran. This is partly because of the recent rapid demographic, social and economic developments, increase in offshore oil and gas activities and also long coastlines available in the country. Wharves، Piers and jetties are lifeline structures, which provide a cost effective means for transporting large quantities of goods and raw materials into and out of a region. Harbor structures also play a central role in management of an abnormal condition such as an earthquake. For long structures such as wharves and jetties, transient ground deformations inducedby seismic wave passage and effects from the spatial difference in ground motion become important. On the other hand, if a port facility is located close to the seismic source, it will become subject to the near field pulse type excitations. An analytical approach has been used to address the problem. Linear and non-linear response of simplified structural models to near-fault and far-fault strong ground motions is investigated. The model approximates a structure by an equivalent oscillator consisting of a rigid beam supported by several rigid mass-less columns. Bi-linear rotational springs connect the columns to the deck and the base of the structure. The system has been studied under two pulses type (fault-normal pulse and fault-parallel pulse) and 108 near field and far field earthquake excitations. In this study closed form solutions for the dynamic response of multi span pile and deck structures have been developed. Material non-linearity, large deformations and P   effects are taken into consideration. The central difference method is employed to solve the nonlinear equations of motion. The model is then used to analyse the structure under incident pulse type near-field excitations. Effects from strain-hardening, columns height, the seismic source distance, magnitude of the excitation, type of the excitation (pulse or random), have been investigated and compute the reduction factor and compare with the common design rules. In general it has been found that the classic design criteria for the strength reduction factors provide non-conservative results in a number of occasions.