In this study, we propose two types of retrofitting methods against fatigue cracking at the upper end of vertical stiffeners under RC slab. They are steel plate reinforcement using a jack-up jig, and angle steel reinforcement using thread rolling screw (TRS). The effectiveness of those two types of retrofitting methods are experimentally investigated through fatigue tests using a large specimen with three main girders under alternative loading using two actuators. As a result, both retrofitting methods can reduce the local stress concentration at the crack initiation point to about half of that before reinforcement, and can prevent fatigue cracking.
In Japan, a lot of steel railway bridges were constructed during the period of rapid economic growth in the 1960s. Now, since over 50 years have passed, the aging of these structures has become conspicuous and a major social problem. In particular, for steel plate girders with open deck system, deterioration and damage due to corrosion are becoming pronounced. Nevertheless, the remaining strength evaluation and its reinforcement methods of corroded structures are not always sufficient. Therefore the purpose of this study is to propose an analytically-based evaluation method and a reliable measure to reinforce in the maintenance field of steel railway bridges.
The purpose of this study is to clarify the influence of scallop details on fracture and deformation capacity of beam-to-column joints. This paper presents the results of full-scale tests of welded beam-to-column joints using SN490B with some type of the scallop details (snip-cut method, non-scallop method and scallop method by using reinforcement welding) on field and shop. Based on the test results, snip-cut of field welding beam-to-column joint have large deformation capacity which is equal or higher than that of shop welding beam-to-column joints.
In Japan, regional governments manage 70% of all bridges, half of which will reach their service life in the near future. However, to maintain this number of bridges, the regional governments always lack resources in finances, specialists and technologies. Therefore, it is necessary to develop a practical method of bridge integrity evaluation to assess the degree of a bridge superstructure’s structural health. This paper proposes a bridge integrity evaluation method by applying support vector machines of artificial intelligence techniques. It is proved that the proposed method helps bridge inspectors and engineers with a more reliable and efficient bridge structural health assessment.
This paper presents an experimental approach on the load carrying capacity of steel pipe beams supported by covered pipes which are adopted in the newly developed plane grid type check dam. The merits of a covered pipe are rapid construction, easy maintenance and increase of structural safety. However, the load carrying capacity of steel pipe beam supported by covered beams is not known yet so far. Therefore, the static loading test is first conducted to investigate the relationship between load and deformation of a steel pipe beam supported by covered pipes. Second, the test results on the load carrying capacity are compared with the ones by the current design formula for a steel fixed pipe beam.
Service lives of steel bridges are limited by corrosion. Coating is commonly applied to steel structures in order to prevent corrosion. In recent years, a laser cleaning treatment is introduced as a new technique for surface preparation of steel structures. However, the influence of laser cleaning on fatigue life of welded joint is unknown. In this study, fatigue tests were conducted on as-welded and laser-treated out-of-plane gusset joints. The test results showed that the laser cleaning treatment only had little influence on fatigue strength of out-of-plane gusset welded joints.