Advanced Materials Research Vols. 163-167

Abstract: Steel bar corrosion monitoring is a very important part of structure health monitoring and full-life design in civil engineering. Many electrochemical methods have been developed in the last decades for corrosion research, but for field corrosion, pulse perturbation is the fast method. The corrosion of Q235 carbon steel in cement mortar has been researched by potentiostatic pulse method. The solution resistance Rs, the polarization resistance Rp, capacity of double layer and time constant have got by cure fitting. The amplitude of voltage perturbation affected the accurate of result little. The polarization resistance decreases with increasing temperature.

Abstract: Corrosion of steel structures has been found to be a problem Corrosion can be managed but not eliminated, so detecting corrosion will remain an issue no matter how effective corrosion prevention programs become. Electrochemical reaction is the basically process of steel corrosion in civil engineering, so electrochemical method is the best way to monitor corrosion grade. Liquid state reference is often used in lab to study steel corrosion by triple electrode system, but it is very difficultly used in steel bar corrosion monitoring in civil engineering. Firstly, liquid reference’s life is, generally speaking, very short. The steel corrosion is a very slow process, corrosion monitoring should be tens of years, so the liquid reference’s life is not long enough for corrosion monitoring; Secondly, the reference electrode’s strength have to be very high. Obviously, liquid electrode reference can not meet the requirement. In this paper, a novel all solid state reference electrode (ASSRE) has been developed. There are three layers in the electrode. Four kinds of components have been included in first and second layer. Additional AgCl powder has been used to inhibit AgCl decrease which is on the surface of Ag wire by complexing effect. There is only one kind of component in third layer. There are four steps to prepare the reference electrode: electrolyze, pre-mixed components, modelling and sintering. Finally, the potential of ASSR has been measured by SCE.

Abstract: The fire-resistant hot-rolled H-beam steel is the newly developed structure material. The development situation of the fire-resistant H-beam steel is briefly introduced. The chemical composition, microstructure, room temperature and high temperature mechanical properties and weldability of several batches of the developed domestic fire-resistant hot-rolled H-beam steels are comprehensively analyzed. The results show that the newly developed hot-rolled fire-resistant H-beam steel has very high room temperature strength, certain high temperature strength, good welding performance, but the toughness needs to be further improved. The performance of web and flange of H-beam steel has large gap.

Abstract: In this paper, the elastic stress and strain fields in curved beams of finite thickness with end moments are systematically investigated using 3D finite element analysis. For a curved beam of finite thickness, the through-thickness distributions of the stress and strain concentration factors are not uniform and their distributions are different. The radius of curvature and the thickness of the beam have significant effect on the stress and stain concentrations. The relations of the maximum value and the value at the corner root of surface of the stress and strain concentration factors with different thickness for various radius of curvature are respectively obtained.

Abstract: The stair is the vertical transport hinge among stories, it becomes a very important component. the stair is seriously damaged in Wenchuan earthquake, and it failed to perform the role for person escaping in case of emergency. a reinforced concrete frame structure with plate stairs as an example, the finite analysis is used. Calculation result shows that plate stairs have a great influence on earthquake resistant behavior of the structure. Designing without the plate staircase in consideration would lead to structural weakness in some columns and cause seriously damage under earthquake and affect the safety of structure.

Abstract: Because of its excellent energy dissipation capacity, friction damper has a wide application in engineering structure, while its use is restricted by constant frictional force. Piezoelectric ceramic actuator has electrochromic deformation ability, by the use of this advantage to combine piezoelectric ceramic actuator with friction damper to form piezoelectric friction damper. This paper conducts some experiments, to study the force output performance and response time of piezoelectric friction damper as well as its hysteretic behavior. The results show piezoelectric friction damper has good force output capacity with the input voltage increases, and the hysteretic behavior is stable, which almost has no relevance with loading frequency.

Abstract: In view of general braces of Pall-typed frictional damper will produce additional axial forces on side column in frame, considering the buckling-restrained braces(BRB) to replace the general braces to make the braces action fully, it would not generate the growth of additional axial forces on side columns, to settle basis for BRBs’ application in Pall friction damping brace system. Because hysteresis behaviors of the Pall-typed friction damper are not affected by brace buckling forces, this paper puts forward that the braces use the ordinary steel plate replacing BRB core plate to do Pall-typed frictional damping brace experimental research, meanwhile considering the geometric nonlinearity the finite element simulation analyses are done for this brace system in ANSYS software. The experimental results and simulation results show that the Pall friction force and brace forces’ variation rule is almost the same, and the brace force is almost the same.

Abstract: Based on the configuration and mechanical characteristics of piezoelectric actuator, the bidirectional piezoelectric variable friction control device which can produce control force in two orthogonal directions was designed and the relation equation of control force with input voltage for this control device was presented. Finally, one piezoelectric variable friction control device was manufactured and performance test of this control device was processed. The result of numerical analysis and experiment shows the bidirectional piezoelectric variable friction control device can produce semi-active control force fast, and the performance of this control device do not change when the frequency of input excitation varies and the control force of this control device has stable mechanical properties.

Abstract: The establishment of an effective finite element model (FEM) for the bridge structure is essential in the health monitoring system of urban grade separation bridge. It inevitably exist inconsistency of response between the FEM and practical structure due to various uncertain factors in the modeling and analysis procedure. Therefore the updating of FEM is necessary. A uniform design-based static model updating method is proposed in this paper, the allowable range of model parameters (the number is ) is divided into several levels (the number is ), the model updating method is transformed into a -factors and -levels test design. Several groups of combined parameters are selected to conduct test through finite element calculation based on the principle of uniform design method, and the optimal parameter group is obtained. This method is applied to the model updating of a complicated special-shaped urban grade separation bridge, and a perfect FEM with a good agreement with measured data is obtained. It confirms the feasibility and superiority of this method.

Abstract: For the purpose of getting a better understanding of failure mechanisms of rock fracturing due to construction perturbation inside the right rock slope of Dagangshan Hydropower Staion, a high precision microseimic monitoring system was installed and preliminary source location data have been investigated. The optimal design of microseimic monitoring network, especially the sensor array was investigated based on P method and Powell algorithm. The positioning accuracy of the system has been adjusted according to artificial fixed blasting tests. The testing results show that microseismic source location error is less than 10 m in the scope of the sensor array, which demonstrates the monitoring system deployed at the right slope has a high positioning accuracy. Signals from 112 microseismic events with moment magnitude ranging from -1.8 to -0.4 were recorded during its 2-month monitoring period. The cluster distribution of microseismic events can reflect directly the construction progresses such as the concentration of microseismicity inside the drainage tunnel at 1081 m level. The present study have significantly improved the understanding of the characteristics of the failure associated with excavation inside the rock slope, and will greatly benefit the potential sliding areas prediction and support of hazards in the phase of construction in future.