The use of approximate methods of seismic assessment of structures

Greece is an earthquake prone area, which is also exposed to coastal environment. Most existing buildings present common characteristics, concerning quality of the materials and environmental conditions [1].The vulnerability of these structures is exteriorized under powerful seismic loads. This is because they were designed, according to older regulations, primarily to bear vertical loads and secondarily to bear horizontal loads, an indicative sign of the absence of anti-seismic design. Designing and evaluation of the seismic performance of existing structures is a really complex issue, because structural degradation phenomenon is related to both corrosion damage of steel reinforcement on RC structures and high vulnerability of masonry. Precisely, the inadequate seismic performance of masonry structures, which is recorded under intense earthquakes, is attributed to the characteristics of masonry and to the ageing phenomena of the materials. For the seismic inspection of masonry structures, both EC2 and OASP can be used [3], although there is often a great misunderstanding concerning the range of the maximum permissible interventions, the financial inability and modern perceptions of redesigning [2]. On the other hand, in the case of RC structures, there is no prediction –concerning the corrosion factor- included in the international regulations and standards. In the current study is presented an experimental procedure, concerning a RC column before and after corrosion. An estimation concerning the drop of its mechanical performance has taken place, indicating the importance of the corrosion factor. Additionally, an existing monumental masonry tower building, was subjected to seismic evaluation [4]. Both OASP and EC2 inspection methods were used. The results pointed out that, for medium–intensity earthquakes, both analytical and approximate methods are respectable and reliable.

Deformation Behavior of Corroded Steel Bar Based on Viscoelastic Theory

This paper shows the corrosion of steel bar from a new perspective with viscoelasticity theory. The strain of steel bar is decomposed as initial elastic strain and creep strain, and the creep strain is caused by corrosion. In order to analysis creep strain, corrosion factor and corrosion strain function were introduced to reflect the deformation behavior. Then integral constitutive relation of corroded bar was deduced according to the above assumption. As a special case of this approach, the corrosion factor of steel bar in atmospheric environment is introduced. The results indicate that the corrosion factor increase with diameter deducing, and the deformation of the steel bar possess the acceleration creep behavior during the corrosion process.

The Corrosion of Concrete Shaft Lining of Mine and its Related Research Progress

With the extensive use of concrete materials, concrete corrosion as an important hazardous factor of engineering safety and its impact on the engineering safety is receiving attention gradually. In order to study its impact on the safety of mining engineering, this paper summarized the corrosion factor of concrete shaft lining of mine and its research progress, and combined with the actual progress of the concrete corrosion. The author came to the conclusion that we should pay attention to the study of the corrosion of concrete shaft lining of mine, at the same time, analyzed the feasibility of the study. The authors believe that, at the present stage, studies of concrete corrosion are more comprehensive and thorough, and coupled with the comprehensive understanding of the underground environment. It is perfectly placed to study the problems of the corrosion of concrete shaft lining of mine deep and systematically.