The water distribution in hardened cement paste with different ages, water to cement ratio (w/c) and different cured methods were investigated by low field NMR. The transverse relaxation time, T2, was used as a parameter to describe the water phase constrained in pores. The results show that the T2 distributions of pastes in the early age are bimodal distribution. As the curing time increase, the T2 distribution peaks shift gradually to the short T2 values reflecting the decrease of mean pore dimension as well as the increase of specific surface area resulted from the gel products. In addition, the influences of initial water to cement ratio and cure methods on water distribution are occurred mainly during the early age. When cured to 28 days, the differences of water distribution in various samples are unconspicuous.

In this paper, an alternative aseismic system for bridge with pile-cap foundation called a separated pile-cap with proper material set in the gap layer was proposed. To simulate the system, a 3-dimensional finite element model for a continuous beam bridge was built. The seismic responses of the model, including behavior of the restrainer, moment at the bottom of the pier and pullout force of the piles with different restrainer lengths under 3 longitudinal artificial earthquake waves were analyzed. The results show that this system can reduce the seismic response significantly.

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Steel fiber reinforced concrete (SFRC) has many good dynamic performances such as toughness and ductility. However, few studies have focused on SFRC’s application in bearing member of bridge structures. In this paper, pseudo-static cyclic tests of eight pier specimens are carried out to investigate seismic behavior of piers using SFRC. The main variables in the testing are the steel fiber content (volume fraction of 0.0%, 0.5%, 1.0% and 1.5%), the length of SFRC region and the stirrup ratio of piers. Seismic behavior of the test specimens, like the failure pattern, the hysteretic characteristics, the skeleton curves, the ductility and the energy dissipation are investigated experimentally. The results show that, 1) the SFRC pier with the steel fiber volume fraction of 1.0% has much better performance than that with other fiber volume contents, particularly for bearing capacity, hysteretic energy dissipation and ductility; 2) the pier specimen can keep sufficient seismic capacity, in which some stirrups are replaced by steel fibers; and 3) compared with specimen with application of SFRC in entire pier, the specimen with appropriate local application of SFRC in potential plastic hinge region can sustain almost the same seismic properties, such as the ultimate bearing capacity, the stiffness, the ductility and the energy dissipation capacity.

The objective of the present work is to propose a new composite seismic isolation system device based on the cable-sliding friction aseismic bearing (CSFAB). Multi-chip steel spiral spring (MSSS) are characterized by unique mechanical properties due to elastic recovery capability. An isolation bearing system based on a MSSS elastic effect is intended to provide recovery properties to reduce or eliminate the residual deformations. The device concept is based on two separate systems, one to transmit the vertical load and to act as a lateral restrainer at meantime, the other contributes to the automatic reset functions in the system. This article presents in detail the mechanical components of the innovative device focusing on its main properties. The load-deformation curve established in this paper is verified to be efficient in describing the mechanical characteristics of the device through experiment. The results could provide reference for study and application of the new composite seismic isolation system.