In order to improve the force performance of traditional anti-buckling energy dissipation bracing with excessive non-recoverable deformation caused by strong seismic action, this paper presents a prestress-braced frame structure system with shape memory alloy (SMA) and investigates its deformation characteristics under a horizontal load. Firstly, this paper establishes a theoretical analysis model by analyzing the geometric relationship between the deformation of SMA cables and inter-story displacement based on the internal force balance equation. The model is used to solve the anti-lateral displacement stiffness of the SMA cable-supported frame structure and to derive a reasonable formula for calculating the initial prestress and cross-sectional area of SMA cables. Then, the mechanical behavior of the SMA cable-supported frame structure system under an equivalent horizontal load is simulated using ABAQUS software and compared with the calculated results of conventional tie-supported and non-dissipative-supported frame structures. The results show that the force performance of the frame structure system determined by the SMA cable design method proposed in this paper is significantly improved under the horizontal load. Furthermore, it can ensure a certain ductility requirement of the frame structure system, which verifies the effectiveness of the design method of the SMA cable frame structure system proposed in this paper.

The force caused by the difference of thermal expansion coefficient between concrete aggregates at ultra-low temperature will inevitably affect the structure and should be considered in the structural design. The coefficient of thermal expansion of cement mortar and stone was measured by resistance strain gage test technology in ultra-low temperature environment, and the variation law of average linear expansion coefficient with temperature was obtained. The results show that the thermal expansion coefficients of cement mortar and stone have similar variation rules with the change of temperature. The stress state of cement mortar and stone under ultra-low temperature does not affect their thermal expansion coefficient. Thermal expansion coefficient of cement mortar under ultra-low temperature is affected by size effect.

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This paper introduces the structure and application method of the self-designed ultra-low temperature mechanical loading test chamber, which can be used to study the coupling effect on building materials induced by temperature change and mechanic force. The results show that the lowest temperature in the chamber can reach to - 169 °C, which can cool the building materials to any specified temperature within 20°C and -169°C. The chamber has the functions of accurately controlling the temperature in the chamber and changing the force on the specimen independently, so that the specimen can always be in the coupling effect induced by temperature change and mechanic force. And the coupling correlation between such two effects can be tested by the device outside of the chamber.

In the construction process of large-scale bridges, there are uncertainties and time-varying factors in the environment and construction loads. It is difficult to make accurate estimates of the theoretical calculation models of construction control in advance. In view of this situation, Bayesian dynamic updating method is introduced to re-estimate the predicted results of the theoretical model. When applying this method, first, the finite element calculation model is determined based on the response surface method, and its calculation results are used as prior information. Then, combined with the actual detection data during the construction process, the Bayesian update formula is derived based on the conjugate prior distribution to correct the theoretical prediction results of bridge construction monitoring. Finally, the actual stress detection data of the control section of high-pier and large-span continuous rigid frame bridges during the construction process illustrate the application process of Bayesian updating in improving the theoretical prediction model. Results indicate that the internal force of the bridge control section obtained by re-evaluating by Bayesian theory not only incorporates the priori information models but also actual monitors sample information during the construction process. The predicted results reflect the true deformation and stress state of the bridge during the bridge construction process and improve the precision of construction monitoring.