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To investigate the seismic behaviour of a new type of concrete-filled precast concrete tubular column, five concrete-filled precast concrete tubular columns varying in concrete strength and stirrup ratio were tested under cyclic loading. The behaviours of the failure mode, hysteretic curve, skeleton curve, bearing capacity, deformability, displacement ductility and energy dissipation were studied to evaluate the seismic resistance performance of the columns. The results show that the failure mode of the concrete-filled precast concrete tubular columns was flexural failure, and the hysteretic curve had a plump shuttle shape, which indicates that the concrete-filled precast concrete tubular column has good energy dissipating capacity. The bearing capacity of the specimen was increased with increasing concrete strength of the precast tube. The stirrup ratio has little effect on its bearing capacity, whereas it has a significant effect on the deformation, ductility and energy dissipation. The story drift of the specimens can meet the requirements of the elastic plastic story drift limit value of 1/50 of the code in China, and the ductility coefficient is greater than 3, which demonstrates that the concrete-filled precast concrete tubular column has excellent seismic properties.

The prefabricated prestressed concrete pavement with assembly construction and prestressing technology has the advantages of rapid construction and reliable quality. In this paper, a three-dimensional finite element model of the pavement structure was established by numerical simulation method. The parameters including the slab dimension, the thickness of the slab, the prestress value and position of the prestress tendon were sensitively analyzed. The results showed that the slab dimension has a critical value of 1m×1m.While the slab is larger than the critical value, the stress of the slab is almost unchanged. The thickness of the slab also has a critical value of 0.12m. When the slab is less than the critical value, the forced mode of the slab will be changed. With the increase of prestress, the stress concentration at the end of the slab will occur, but the maximum stress did not exceeded the strength of the material. It is suggested that the prestress value should be 4-5MPa. The lower the position of the prestress tendon in the slab is, the more obvious the anti-arch effect is, and it is safe to set the prestress tendon in the middle of the slab.

Conical diffraction, a unique optical phenomenon in biaxial crystal, has important applications for the manipulation of particles. In this paper, a new model of annular Gaussian beam is constructed based on the Tovar's flat-topped multi-Gaussian laser beams. The conical diffraction of annular Gaussian beam is calculated using Belsky-Khapalyuk-Berry theory. The polarization characteristics of conical diffracted output beams under the annular Gaussian beam are theoretically calculated and experimentally demonstrated by means of the linearly polarized annular Gaussian beams with different polarization directions. It is found that the same azimuth angles of the inner and outer rings of the conical diffracted output beams have orthogonal polarization characteristics. A combined polarizer (CP) composed of eight polarizing segments with different specific pass axes of polarization is presented to simulate the polarization characteristic of the optical field of conical diffraction. Furthermore the calculations for output-field control of conical diffraction under the annular beam by using the proposed CP are compared with the experimental results. The results show that the intensities of both the inner and outer rings are periodically varied with CP azimuth angle. And when the azimuth angle of CP is 0, only the conical diffracted outer ring is remained, while only the inner ring of conical diffraction is remained for 180. This tunable conical diffracted field has important applications in optical tweezers and wavelength division multiplexing.

In this paper, the horizontal web reinforcement is proposed as shear reinforcement along the depth of the beam according to oblique section shear mechanism and analyze its shear performance using the finite element software ANSYS. The research shows that the horizontal web reinforcements can carry the horizontal component of the principal tension stress and stirrups carry the vertical component. The horizontal web reinforcements and stirrups together form the integrated shear model to limit the diagonal cracks development as well as reduce the width of diagonal cracks. It proposed the formula of calculating width of diagonal cracks in conjunction with finite element results.