Ryo KOMAGATA In this study, the deterioration, damages and structural characteristics were grasped for the managed bridge and column of old movable gate dam which was used by 2011 for about 80 years. Damage figures of the bridge, and expected bar arrangement figures of column were made through the field work with scrapping. In addition, tensile tests for collected rebars at the time were done. As a result, the damage such as exposed rebars was confirmed at old movable dam, however, it had enough performance as structure.
key words: old movable dam , managed bridge , column , bar arrangement , deterioration damages
Kento NAKAJIMA The purpose of this study is to grasp tendency of deteriorations and damages of bridges witch were inspected two times from 2004 to 2010 managed by road administrator in Hokuriku district. Inspection's Database was created and statistical analysis was conducted. Also based on the results of statistical analysis, detailed examine about damage status was done in terms of their locations and so on with the pictures of survey reports. As a result, some tendency with damages patterns and factor of them were confirmed. For example, serious damages which influenced on durability performance highly occurred when the bridges were old. In addition, most of damage factor in chloride induce area was induced by poor drainage such as sediment closure.
key words: bridge maintenances, periodical inspection, deteriorations and damage condition, damage factor
Kenta AKAHARA Bridge management is more important, however, current, regular inspection needs a lot of effort and cost. Therefore, before regular inspection, judging necessity of regular inspection will be effective by simple methodology. In this study, a brief inspection system was developed, and minimizing the work to input and process data was tried with tablet computer in site. The field test was performed to examine the usability and validity of this brief inspection and the result was compared with the regular one. As a result, some validity and a few of problem were found through the test.
key words: brief inspection, tablet computer, database, field test
Takuya UCHIYAMA Crack observation and hammering test were performed for pre-tensioning system PC pedestrian bridge girder with corrosion of reinforcement due to salt damage that had been used for 35 years along the coast of the Japan Sea. Through the bending loading test, the Girder A was found broken as shear failure, and the Girder B as flexural failure. After the loading test, PC steel material in tensile area was taken and the corrosion loss, the position of subsidiary fracture or disappearance point was confirmed. Also, the calculated load carrying capacity was estimated a little smaller than experimental one.
key words: prestressed concrete, salt damage, corrosion of reinforcement, load carrying capacity, maintenance
Keita WATANABE For dynamic analyzing with high accuracy is necessary to clarify the static deformation characteristics of both beam and column. In this study, static analysis of RC piers, RC rigid frame piers and RC beams were done to check the accuracy of a fiber model, which is considered high applicability with flexure fracture of structure, and those results were compared with the load displacement relationship from the past experiments. It was shown that analysis results were in accordance with that of the past experiments. Then, RC bridge beam that was received salt damage 79 years past was static analyzed and compared with static-loading experiment. Seismic response analysis as a structural system was performed in terms of both relatively healthy 'inside beam', and relatively deteriorated 'outside beam' and earthquake proof safety was examined. As a result, the response displacement of 'inside beam' was shown within the elastic range, however, the residual deformation in that of 'outside beam' was found due to its transition to plastic range. Accordingly, the decline of earthquake proof safety as structural system was identified when a bridge had the deteriorated beams.
key words: reinforced concrete, fiber model, static analysis, seismic response analysis
Takeru ARAKAWA Structures using Fiber reinforced plastics (FRP) have high-corrosion resistance for many kinds of decay. Simple beam FRP pedestrian bridge has already used in bridge engineering. Examination of vibration performance is essential, however, vibration characteristics of structure with FRP are not sufficiently grasped. In this study, comparison of static and dynamic response between measured value and analytical one by FEM analysis software OpenSees are made, and the vibration characteristics of FRP bridge are clarified. The response displacement of examination object was smaller than that of traditional types model. Also the result for character frequency was equivalent to the described one.
key words: Fiber Reinforced Plastics，Pedestrian Truss Bridge，Finite Element Method，OpenSees，Spectrum Analysis
Masaki KOYAMA The effectiveness of prediction methods by between the FORTRAN elasto-plastic response analysis program and OpenSees, which was newly used as FEM analysis program, was compared on the both values of earthquake input unit energy and equivalent cumulative energy, to examine the accuracy of prediction method of damage level of civil structure. As a result, predicted value and practical one were not accorded in both programs as the earthquake input unit energy became large. However, some coincidences in OpenSees were admitted, and its effectiveness of estimation value was confirmed.
key words: seismic design, earthquake input unit energy, equivalent cumulative energy, elasto-plastic response analysis.
Yukitada SHIRATA It is necessary to predict and evaluate the deterioration level of reinforced concrete structure with chloride attack efficiently to repair or reinforce it, however the information about the evaluation of its durability is not effectively arranged because the kind of structure, environment, investigate methods are different. The measurement database of chloride attack with the function for judging the risk level by chloride attack with Microsoft Access was developed to clarify the investigation items and arrange and unify the investigated information. The prediction of the density of the chloride ion by using the sample data was done and its availability was partially shown with some improvement for operation and convenience.
Key Words: database, chloride attack, Microsoft Access, risk evaluation
Ryo ISHINO Influence of snow load on earthquake damage of two-story wooden houses was examined using seismic response analysis. Mass of wooden houses were calculated at each composition member of houses. Relationships between the thickness of roof snow and the moment by force occurring at the bottom of structure due to the weight of building with roof snow and the horizontal response displacement of structure, P-册ffect. As a result, Influence of snow load on damage of wooden houses was heavier damage than new houses. Small difference of the load of snow had a large influence on the houses when period of houses is corresponding to the one of earthquake wave.
Key Words：snow load, wooden house, seismic response analysis, response acceleration spectrum, P- effect
Akiyuki SAITO Fiber reinforced plastics (FRP) has drawn attention as a new construction material. However seismic response characteristics of bridge made of FRP are not sufficiently grasped. In addition, the evaluation by dynamic analysis for bridge designs has been taken up. In this study, seismic response characteristics of hybrid truss bridge combining FRP and steel material SS400 were investigated. Dynamic analysis was carried out for a single material bridge with SS400 and hybrid material bridge with GFRP, and response acceleration and displacement were analyzed. As a result, the result for hybrid truss bridge was the same or better than the one for single material bridge with SS400.
key words : Fiber Reinforced Plastics，Dynamic Finite Element Analysis，Seismic Response Analysis，3D Truss Bridge Model
Yoichi OTSUKA Most designs of RC structures are designed by the regression formula that is generally suggested by experiments. It is appropriate that these equations are adopted only for limited conditions, because those are based on a lot of experiment results, and acquired by the applicable range. In this study, shear strength of high strength concrete(HSC) beams without web reinforcement is not evaluated by the regression formula as original, but by modified compression field theory(MCFT) proposed by Collins et al., that is, solving shear problems by dynamical approach. It is also compared with the past experiment results based on conventional methods to evaluate application of this analytical method. As a result, the following results were acquired; this analytical result agreed with the past experiment results on the whole, and that the shear strength of HSC RC beams and the shear strength based on conventional methods could evaluate by same accuracy of this method.
Key Words：Modified Compression Field Theory(MCFT)，Shear Strength Capacity，High Strength Concrete(HSC) Beams without Web Reinforcement, Diagonal Tension Failure
Otowa MATSUDA In this study, accuracy of damage estimation of RC pier was examined by unit energy with in a unit period in the earthquake, and equivalent accumulative energy of structure using seismic wave data of Niigata-ken Chuetsu earthquake, occurred in October 23, 2004. As a result, accuracy of estimation was found to be widely, affected by energy volume, shapes of earthquake energy spectra, and equivalent accumulative energy volume of structure. If was also found that equivalent period should be considered by the one which was used ductility factor proposed by Ishibashi.
key words : Reinforced Concrete Pier, Seismic Design, Earthquake Input Unit Energy, Equivalent Accumulative Energy, Energy Spectrum,
Masatoshi WATANABE In recent years, fiber reinforced plastics (FRP) has drawn attention as a new construction material over the world. The pedestrian bridge with glass fiber reinforced plastics was constructed as a site-test in Okinawa prefecture, Japan. New material is considered in near future because designing method will shift to the new method. The evaluation by dynamic analysis for bridge designs has been taken up after the Hyogo-ken Nanbu Earthquake. In this study, as for the hybrid material structure combined the FRP with current material, cost convert weight, natural frequency and unit length weight were calculated by static analysis with finite element method, and response acceleration and response displacement were examined by dynamic analysis when a real-seismic wave was inputted. As a result, as for the hybrid material structure, possibility of efficiency for cost convert weight could be seen when the combined materials was properly placed. The advantage of vibration characteristics, such as dumping, could be confirmed comparing with the single material when the combined materials were applied.
Key words : Fiber reinforced plastics (FRP), Cost convert weight, natural frequency, Unit length weight, Response acceleration, Response displacement