This study examines the rheological properties of shear thickening fluid (STF) enhanced by additives such as multi-walled carbon nanotubes (MWCNTs), polyvinylpyrrolidone (PVP), and nano-silica (SiO2) at different mass fraction ratios. The rheological properties of the liquid (MWCNTs–PVP/SiO2–STF) and the effect of the rheological properties of the STF under different plate spacing of the rheometer were investigated. The optimal mass fraction mixing ratio was also studied. The MWCNTs–PVP/SiO2–STF system with different PVP mass fractions was fabricated using ultrasonic technology and the mechanical stirring method. Then, the steady-state rheological test of the MWCNTs–PVP/SiO2–STF system was carried out with the aid of the rheometer facility. Dynamic rheological and temperature sensitivity tests on the MWCNTs–PVP/SiO2–STF system with 0.1 and 0.15% PVP mass fractions were performed. The rheological test results show that the MWCNTs–PVP/SiO2–STF system has a significant shear thickening effect when the PVP mass fraction is increased from 0 to 0.15%. When the PVP mass fraction is 0.1% and the plate spacing is 1 mm, the system exhibits the best shear thickening performance. This is based on the following facts: the viscosity can be achieved as 216.75 Pa s; the maximum energy storage and energy consumption capabilities can be observed. As a result, PVP can significantly enhance the shear thickening performance of the MWCNTs/SiO2–STF system.

Traditional reinforced concrete columns have demonstrated poor seismic performance especially in corrosive environment as the reinforcement bars experience severe corrosion under such conditions. To overcome the problem of steel corrosion, glass fiber-reinforced polymer (GFRP) reinforced concrete columns have gained significant attention in recent years. However, the seismic performance of GFRP reinforced concrete column is not well understood yet. One of the main challenges associated with the use of GFRP bars is its brittle behavior. Therefore, it is necessary to investigate the mechanical properties and failure modes of GFRP reinforced concrete structures under seismic action. In this research, the seismic behavior of GFRP reinforced concrete columns and conventional columns under different axial compression ratios are analyzed by low-cycle repeated pseudo-static loading tests. As a result, the deformation and the seismic energy dissipation capacity of GFRP reinforced concrete columns are investigated and discussed. Furthermore, the failure mechanism of GFRP bar structure is studied to provide the basis for improving the seismic design method of GFRP reinforced concrete structure and modifying the code for seismic design. In addition, the influence of axial compression ratio on the seismic behavior of full GFRP reinforced concrete columns is investigated. The results of this experiment demonstrate that with the increase of axial compression ratio, the ultimate bearing capacity of GFRP reinforced concrete columns increases, while the deformation and the cumulative energy dissipation capacity decrease.

The sandwich structures are three- or multilayered structures such that their mechanical properties are better than each single layer. In the current research, a three-layered cylindrical shell including a functionally graded porous core and two reinforced nanocomposite face sheets resting on the Pasternak foundation is used as model to provide a comprehensive understanding of vibrational behavior of such structures. The core is made of limestone, while the epoxy is utilized as the top and bottom layers’ matrix phase and also it is reinforced by the graphene nanoplatelets (GNPs). The pattern of the GNPs dispersion and the pores distribution play a crucial role at the continuous change of the layers’ properties. The sinusoidal shear deformation shells theory and the Hamilton’s principle are employed to derive the equations of motion for the mentioned cylindrical sandwich shell. Ultimately, the impacts of the model’s geometry, foundation moduli, mode number, and deviatory radius on the vibrational behavior are investigated and discussed. It is revealed that the natural frequency and rotation angle of the sandwich shell are directly related. Moreover, mid-radius to thickness ratio enhancement results in the natural frequency reduction. The results of this study can be helpful for the future investigations in such a broad context. Furthermore, for the pipe factories current study can be effective at their designing procedure.

In order to make the performance evaluation of asphalt pavement more scientific and reasonable, the author put forward an evaluation method based on SOM neural Network. This method takes comprehensive consideration of four affecting factors including pavement ride quality, pavement condition, pavement structure bearing capacity and pavement skid resistance. Then designs and simulates the SOMNN programming to comprehensive evaluate the pavement performance. Finally, the method was verified by an example, and the calculation has been compared with the traditional evaluation methods. Results showed that the method was reasonable and effective. Compared with others, this method was simpler, cheaper and easier to promote and has better superiority.

Firstly, a series of model tests of free spanning submarine pipeline are carried out on an underwater shaking table in the State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology. Hydrodynamic forces imposed on the span of submarine pipeline due to different direction excitations are studied. Secondly, finite element method on the base of the theory of interaction between fluid and structure is utilized to analyze the dynamic response of free spanning submarine pipelines subjected to earthquakes. Thirdly, based on Morison equation an improved hydrodynamic force model considering the effects of seismic exciting directions is proposed. Discretized equations of motion derived from the improved Morison equation is employed to analyze the dynamic response of free spanning submarine pipelines subjected to earthquakes. FE model is established to simulate the above experimental conditions. Finally, the comparison of numerical results with experimental results shows that the improved hydrodynamic force model could satisfactorily predict dynamic response on the free spanning submarine pipelines subjected to earthquakes.