Involvements of Stress Triaxiality in the Brittle Fracture during Earthquakes in Steel Bridge Bents

Hiroshi Tamura,Eiichi Sasaki,Hitoshi Yamada,Hiroshi Katsuchi,Theeraphong Chanpheng 한국강구조학회 2009 International Journal of Steel Structures Vol.9 No.3

Stress triaxiality is proposed as one of the key parameters to discuss the cause of brittle fracture during earthquakes in steel structures. This study analytically investigated the features of stress triaxiality in steel bridge bent subjected to earthquakes. The target structure is a steel bridge bent actually fractured during the South Hyogo prefecture Earthquake. From the investigations, it was confirmed that high stress triaxiality was generated at a point supposed as fracture origin. There is a possibility that the triaxiality was involved in the fracture strongly through the increase of maximum principal stress. Moreover, from the analyses accounting for several kinds of large earthquake waveforms, it was indicated that threre is possibility that the distribution of triaxiality around the fracture origin was not affected by significantly by each cycle and each waveform. Stress triaxiality is proposed as one of the key parameters to discuss the cause of brittle fracture during earthquakes in steel structures. This study analytically investigated the features of stress triaxiality in steel bridge bent subjected to earthquakes. The target structure is a steel bridge bent actually fractured during the South Hyogo prefecture Earthquake. From the investigations, it was confirmed that high stress triaxiality was generated at a point supposed as fracture origin. There is a possibility that the triaxiality was involved in the fracture strongly through the increase of maximum principal stress. Moreover, from the analyses accounting for several kinds of large earthquake waveforms, it was indicated that threre is possibility that the distribution of triaxiality around the fracture origin was not affected by significantly by each cycle and each waveform.

Direct identification of aeroelastic force coefficients using forced vibration method

Herry Irpanni,Hiroshi Katsuchi,Hitoshi Yamada 한국풍공학회 2022 Wind and Structures, An International Journal (WAS Vol.35 No.5

This study investigates the applicability of the direct identification of flutter derivatives in the time domain using Rational Function Approximation (RFA), where the extraction procedure requires either a combination of at least two wind speeds or one wind speed. In the frequency domain, flutter derivatives are identified at every wind speed. The ease of identifying flutter derivatives in the time domain creates a paradox because flutter derivative patterns sometimes change in higher-order polynomials. The first step involves a numerical study of RFA extractions for different deck shapes from existing bridges to verify the accurate wind speed combination for the extraction. The second step involves validating numerical simulation results through a wind tunnel experiment using the forced vibration method in one degree of freedom. The findings of the RFA extraction are compared to those obtained using the analytical solution. The numerical study and the wind tunnel experiment results are in good agreement. The results show that the evolution pattern of flutter derivatives determines the accuracy of the direct identification of RFA.

Study on the Assessment of Fatigue Durability of Corroded Steel Girder Ends Repaired with Carbon Fiber Reinforced Polymer

Rusandi Noor,Hiroshi Tamura,Hiroshi Katsuchi,Wang Jiaqi 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.6

Bridge maintenance and repair have gained significant attention as their service life continues to extend. Numerous retrofit projects have been implemented to address the corrosion issues at steel plate girders’ ends. This study focuses on evaluating the durability of the retrofitted part of the steel girder end by assessing its ability to sustain eccentric fatigue load and recognizing the possibilities of CFRP post-retrofitted damage. The novel specimen was designed to replicate corrosion on the inner side of exterior steel girder web ends and study the effect of retrofitting them with CFRP. In addition, a new bending fixture design based on the specimen design was proposed to reproduce the actual severe loading mode of a CFRP-retrofitted steel girder end. Polyurea putty (FU-Z) was used to identify the durability owing to its flexible characteristics under fatigue. The lifecycle-oriented experimental results showed that the specimens with CFRP-retrofitted steel girder ends survived for 3.5 million cycles under fatigue loading. However, specimens without polyurea putty exhibited damage characteristics, such as detachment and delamination. In addition, the shifted local stress detection of the edge joint represented the detachment of the retrofit material at 3 million cycles. The detachment occurred at the end of the corrosion web edge and delamination was observed in the cutoff section, which reduced the local bonding of 50% of the CFRP sheets. In addition, local damage resulted in durability resistance developed under elastic conditions.

Experimental and Numerical Evaluation of Bearing Capacity of Steel Plate Girder Affected by End Panel Corrosion

Nauman Khurram,Eiichi Sasaki,Hiroshi Katsuchi,Hitoshi Yamada 한국강구조학회 2014 International Journal of Steel Structures Vol.14 No.3

The present study deals with the effect of uniform and non-uniform local corrosion damages at the bearing stiffener andnearby web on the bearing capacity of plate girder. Five plate girder ends simulated with different uniform and non-uniformtypes of corrosion damage, at the base of the bearing stiffener are used in the experimental program. The experimental resultsare modeled and verified on a Finite Element (FE) software ABAQUS, considering shell-solid coupling elements formulation. The study is further extended to various damage cases i.e., stiffener damage, stiffer plus web damages etc. considering differentdamage heights and residual thicknesses. The study concludes that minimum thickness within any damage height may be usedto simulate the corrosion damage in a FE analysis. At the end, some empirical relationships are also proposed to estimate thebearing strength of the plate girder affected by the local corrosion damage at plate girder end.

Experimental and Numerical Evaluation of Bearing Capacity of Steel Plate Girder Affected by End Panel Corrosion

Nauman Khurram,Eiichi Sasaki,Hiroshi Katsuchi,Hitoshi Yamada 한국강구조학회 2015 International Journal of Steel Structures Vol.15 No.1

The present study deals with the effect of uniform and non-uniform local corrosion damages at the bearing stiffener and nearby web on the bearing capacity of plate girder. Five plate girder ends simulated with different uniform and non-uniform types of corrosion damage, at the base of the bearing stiffener are used in the experimental program. The experimental results are modeled and verified on a Finite Element (FE) software ABAQUS, considering shell-solid coupling elements formulation. The study is further extended to various damage cases i.e., stiffener damage, stiffer plus web damages etc. considering different damage heights and residual thicknesses. The study concludes that minimum thickness within any damage height may be used to simulate the corrosion damage in a FE analysis. At the end, some empirical relationships are also proposed to estimate the bearing strength of the plate girder affected by the local corrosion damage at plate girder end.

Influence of geometric configuration on aerodynamics of streamlined bridge deck by unsteady RANS

Md. N. Haque,Hiroshi Katsuchi,Hitoshi Yamada,Haeyoung Kim 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.28 No.5

Long-span bridge decks are often shaped as streamlined to improve the aerodynamic performance of the deck. There are a number of important shaping parameters for a streamlined bridge deck. Their effects on aerodynamics should be well understood for shaping the bridge deck efficiently and for facilitating the bridge deck design procedure. This study examined the effect of various shaping parameters such as the bottom plate slope, width ratio and side ratio on aerodynamic responses of single box streamlined bridge decks by employing unsteady RANS simulation. Steady state responses and flow field were analyzed in detail for wide range of bottom plate slopes, width and side ratios. Then for a particular deck shape Reynolds number effect was investigated by varying its value from 1.65x104 to 25x104. The aerodynamic response showed very high sensitivity to the considered shaping parameters and exhibited high aerodynamic performance for a particular combination of shaping parameters.

Finite Element Investigation of Shear Capacity of Locally Corroded End Panel of Steel Plate Girder

Nauman Khurram,Eiichi Sasaki,Hiroshi Katsuchi,Hitoshi Yamada 한국강구조학회 2013 International Journal of Steel Structures Vol.13 No.4

This study discusses the effect of local corrosion damages nearby the bearing region including the bearing stiffener andadjacent web damage on the ultimate shear and post-buckling strength of steel plate girder bridges. A computer packageABAQUS is utilized for the verification and extension of the numerical study. Various corrosion damage cases, specifically thebearing stiffener are studied considering different damage thickness and damage heights. The study concludes that local damageon bearing stiffener damage is more fatal than the local web damage for the shear resistance of the plate girder. Further, someempirical relationships are also derived to assess the residual shear capacity of the locally corroded plate girder at the bearingregion.