Nowadays, the comfort of drivers and passengers is drawing more and more attention. The interaction between vehicles and the asphalt road can cause coupled vibration and reduce the comfort of passengers. Therefore, the research on human–vehicle–road coupled vibration and the comfort of passengers is of great importance. In this paper, the three-dimensional human–bus–road coupled vibration system is established, including the bus model, the parallel biomechanical human model with 2 degrees-of-freedom (DOF), and road surface roughness condition. The proposed coupled model was then used to study the dynamic response of the system and the comfort evaluation of the human body. In the comfort evaluation, the annoyance rate based method was proposed to consider the randomness of passenger vibration, the difference of the psychosensory vibration, and the fuzziness of evaluation indicators. Compared to the fuzzy evaluation based on the ISO 2631 standard, the proposed annoyance rate based method gives a quantitative evaluation of human comfort. Not only the degree of comfort can be evaluated, but the percentage of people feeling uncomfortable can also be obtained. Finally, parametric studies were conducted to investigate the effects of road surface roughness, interlayer bonding condition, bus weight, bus speed, and sitting position. It is found that the road surface roughness has the most significant effect on human comfort.

The study in this paper aims to evaluate the effects of vehicle‐bridge coupled vibration on the vehicle ride comfort. The mechanical model of both vehicle and bridge subsystems and the vibration differential equations are established, respectively, based on the principle of dynamic balance and finite element method. The APDL command stream for iterative calculation is compiled on the ANSYS platform. The method to evaluate the vehicle ride comfort is established according to the criteria in ISO2631‐1‐1997. The vehicle dynamic responses and ride comfort are analyzed considering different pavement levels while multiple vehicles pass through the cable‐stayed bridge. The analysis results indicate that the dynamic responses of vehicles decrease with the improvement of pavement roughness, resulting in the vehicle ride comfort to be better; the dynamic responses of vehicles increase with the increment of vehicle speed or the decrement of vehicle gravity, resulting in the vehicle ride comfort to be worse. The present research results can provide an insight into the rational design of bridge structure so as to reduce the vehicle‐bridge coupling vibration responses and improve the ride quality of drivers and passengers.

A pipeline at an offshore oil field in China South Sea is constructed. The structural design of the offshore pipeline addresses the ability to withstand operating, testing and installation stresses in the pipe as well as the ability of the pipeline system to withstand environmental forces. On the basis of design premise, stress analysis was performed using the method and procedures included in the DnV code. For in-place stress analysis, two general types of stress determination were made: hoop stress and equivalent stress. Hoop, or circumferential stress is a common computation and its magnitude depends on the pressures acting on the pipe wall. Equivalent, or Von Mises stresses are longitudinal and the effects of pressure, temperature and bending due to the external loading were considered. The calculation for unsupported span was performed considering static and dynamic situations. The thermal, pressure, soil friction restraint and externally applied axial forces were considered when calculating the stress in expansions experienced at the ends of offshore pipeline. The structural design is performed on the basis of the above stress analysis.

Due to its advantages, trenchless technology has been widely used all over the world during construction of underground pipelines, and horizontal directional drilling is the most popular trenchless technology. Because a drilling rod is subjected to the most complicated stress and the harshest working condition among all components in a horizontal directional drilling system, this paper lays emphasis on stress analysis of drilling rods. The finite element method and the computer software ANSYS are used to calculate the stress in the drilling rod. Also, the effects of torsional moment on the stress value and distribution are analyzed as well. The results of the above analyses give the location of the maximum Von Mises stress along the rod and indicate the relationship between maximum stress and the curvature radius of drilling rod. Generally speaking, the maximum stress usually occurs near the joints of the drilling rod, the rod stress decreases with an increase in curvature radius, and an increase in the torsional moment on the drilling rod can significantly increase the rod stress.

When fluid passes through a bluff structure, it will separate, thus creating vortex and resulting in the coupled vibration between the fluid and structure. Under certain condition, the vibration is significant, and the structure will damage due to the reduction of fatigue life. With the development of ocean engineering into the deep water areas, it is very important to study the vortex-induced vibration of submarine pipelines. Due to the complexity of the problem, theoretical and experimental methods are usually used to study the problem simultaneously, and the latter is often more important. The model experiments are carried out in a laboratory in this study, and the experimental results reflect the main characteristics of vortex-induced vibration. Also, the experimental results and theoretical results are roughly consistent with each other. With the increment of the fluid velocity, the vortex shedding frequency will approach a natural frequency of the structure, and then the strong interaction between the fluid and structure will arise that the structures may damage.

The offshore riser and pipeline with an unsupported span are usually subjected to the vibration due to vortex-shedding. To analyze the vortex-induced vibration of offshore pipelines in steady current, an elastically supported rigid hollow cylinder is used as a calculation model with single freedom. The fluid forces acting on the cylinder are divided into lift and fluid reaction. A simplified method to analyze vortex-induced vibration of cylinder is established. The method transfers the structural vibration differential equation into algebraic equations and the empirical formulae about fluid force coefficient are put forward. The results calculated by above method indicate that the vortex-induced vibration of a cylinder is mainly controlled by reduced velocity, usually, the locking-in phenomenon occurs when the reduced velocity falls between 4.0 and 9.0, and the maximum vibration amplitude occurs when the reduced velocity falls between 6.25 and 7.5. The method presented in this paper is a feasible one to predict the vortex-induced vibration of a cylinder.