This study is aim at evaluating ultimate seismic capacity of a steel moment-resisting frame by conducting scale model tests, whose performance is improved by two structural systems. One is a proposed pinned column support system, which prevents the first story's columns from yielding, and the other is a leaning column, which controls a deformation pattern of a main frame. Furthermore, the virtual work method is applied to predict collapse mechanisms, considering the effect of beam-column flexural stiffness distribution and increase in flexural strength due to strain hardening. The method successfully predicts collapse mechanism of frames with some modification, estimated by static analysis and scaled model tests.
This paper conducts a buckling analysis to find a relationship between the global load factor and reliability index in the case of a simply supported cylindrical lattice shell under dead and uniform snow load. First, the probabilistic properties of buckling load are studied to find the average and standard deviation. Second, the performance function is solved to obtain its reliability, leading the relationship between snow load factor and probability index considering 50 cm snow fall for 100-year reference period. Third, the relationship is converted to the relationship between the global load factor and reliability index. Finally, some applications and discussions are given for safety of the shells under severe snow load.
CT From the viewpoint of maintenance of steel bridges, it is necessary to develop corrosion protection methods for structural members especially susceptible to corrosion damage, such as girder-ends, high-strength bolts and edge surfaces. In order to clarify the corrosion protection property of Cold Spray method with mixed particles of zinc and alumina for corroded steel substrate, accelerated corrosion test and open-circuit potential measurement were carried out. The influence of alumina particle in cold sprayed composite coating on the corrosion behavior of the coating was investigated using the potentiodynamic polarization measurements.
Bridge washing is a simple and effective method to reduce the corrosion process. However, since the corrosion environment, such as quantity of airborne salt, is different depending on the region and members, it is not clear that the effective washing frequency. In this study, the effective frequency of bridge washing has been investigated. The exposure tests with several washing frequencies as a parameter were performed. In comparison to the results of corrosion environment survey, it was clarified the frequency of the bridge washing on the horizontal surface where the airborne salt tends to accumulate, such as lower flanges, must be multi times per year.
Seismic retrofit by the addition of H-section haunches has been developed by the authors to improve plastic deformation capacity of beam-to-column connection in existing building structures. The design criterion that the moment demand on original beam-to-column connection keeps below its plastic moment capacity, has been proposed to achieve satisfactory performance. For this purpose, the simple estimation of moment transferred by haunch is necessary. In this paper, simplified strut modelling (SSM) proposed by the authors was extended to account for the haunch connectedto RHS column through external diaphragm. The validity of extended SSM was verified by comparison to finite element analysis results.
This paper deals with the improvement of program that was developed to analyze elasto-plastic behavior of steel square tube columns with local buckling. The improvements are the suggestion of new deteriorating hysterical rule and step by step update of plastic stiffness which can consider the effect of axial force ratio and the direction of member-end-rotation. The operation of program has been checked by the analytical examples of single column member and three dimensional building frame.