scholarly journals NON-DESTRUCTIVE EVALUATION FOR HORIZONTAL CRACKS IN EXISTING RC SLABS BY ANALYSIS-AIDED IMPACT ELASTIC-WAVE METHODS

2012 ◽  
Vol 06 ◽  
pp. 670-675
Author(s):  
Heung-Soo Lee ◽  
Toshiro Kamada ◽  
Shinya Uchida ◽  
Toshiki Iwasaki
Keyword(s):  
Elastic Wave ◽  
Highway Bridges ◽  
Bottom Surface ◽  
Response Analysis ◽  
Wave Method ◽  
Rc Slab ◽  
Ball Diameter ◽  
Rc Slabs ◽  
Wave Methods ◽  
Non Destructive

In this study, impact elastic-wave method was performed at the bottom surface of RC slab cut from an existing highway bridges to survey the horizontal cracks. Before measurements by impact elastic-wave method, impact response analysis was applied to determine optimal steel ball diameter, distance between impact point and receiving point of elastic-wave. Efficiency of analysis-aided impact elastic-wave method was confirmed by drilling and observing the interior of the RC slab by stick scanner. Evaluation results by this method agreed well with results of visual inspection. Thus, validity of the analysis-aided impact elastic-wave method on detection of horizontal cracks in RC slabs of highway bridges was demonstrated.

Dynamic Response Analysis and Optimal Design of a RC Slab to Blast Loads

2010 ◽  
Vol 163-167 ◽  
pp. 2390-2396 ◽  
Author(s):  
Wen Bin Sun
Keyword(s):  
Dynamic Response ◽  
Reinforcement Ratio ◽  
Response Analysis ◽  
Trial And Error ◽  
Blast Loads ◽  
Deflection Curve ◽  
Dynamic Response Analysis ◽  
Rc Slab ◽  
Rc Slabs ◽  
Current Guidelines

Current guidelines such as TM5 and ASCE use a trial and error procedure to design RC slabs against blast loads. Although the trial and error procedure is easy to implement, it may not result in a optimal to resist blast loads. In this study, SDOF system recommended by TM5 and ASCE was adopted to simplify RC slabs; the bilinear model was selected to simulate the resistance-deflection curve for dynamic response analysis. After comparing the areas under the resistance-deflection curves of RC slabs with different reinforcement ratios, the reinforcement ratio responding to the biggest area can be defined as the optimal reinforcement ratio. These derived relationships are useful to facilitate a design with maximum capacities to resist blast loads.

scholarly journals Vibration-based damage identification for reinforced concrete slab-type structures using fiber-optic sensors and random decrement technique

2020 ◽  
Vol 4 ◽  
pp. 163-171
Author(s):  
Azita Pourrastegar ◽  
Hesham Othman ◽  
Hesham Marzouk
Keyword(s):  
Fiber Optic ◽  
Damage Identification ◽  
Processing Technique ◽  
Fiber Optic Sensors ◽  
Modal Testing ◽  
Identification System ◽  
Random Decrement ◽  
Rc Slab ◽  
Rc Slabs ◽  
Non Destructive

This paper presents and evaluates a damage identification system for reinforced concrete (RC) slab-type structures based on non-destructive vibration testing, Random decrement (RD) signal processing technique, and embedded smart network of fiber-optic sensors. The proposed system aims to overcome the challenges associated with the use of electrical sensors and signal processing of noisy dynamic data. Two experimental modal analysis investigations have been conducted. First modal testing focuses on investigating the capability of fiber-optic sensors and Multi-channel random decrement (MCRD) processing technique to locate damage in RC slabs through changes in the first mode shape response with damage. The second modal testing focuses on the detection of damage intensity using the RD technique through the change in frequency and damping dynamic parameters. The results show that RD technique can be used effectively to extract the free vibration response of RC slab-type structures; fiber-optic sensors are more sensitive to capture damage severity in comparison to electrical accelerometer sensors, especially, at steel yielding and failure load;  MCRD technique can be used effectively to generate mode shapes for RC slabs based on fiber-optic grating FBG sensors measurements. On the other hand, electrical strain gauges were noisy and it was difficult to obtain any measurable data; A damage identification system based on non-destructive vibration testing, MCRD  processing technique, and using an embedded smart network of fiber-optic sensors can estimate accurately the damage location through changes in the first mode shape.

scholarly journals Probabilistic seismic response analysis of coastal highway bridges under scour and liquefaction conditions: does the hydrodynamic effect matter?

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Xiaowei Wang ◽  
Yutao Pang ◽  
Aijun Ye
Keyword(s):  
Seismic Response ◽  
Seismic Design ◽  
Highway Bridges ◽  
Element Model ◽  
Response Analysis ◽  
Hydrodynamic Effect ◽  
Strong Earthquakes ◽  
Influence Of Water ◽  
Scour Hazard ◽  
Ground Motion Records

AbstractCoastal highway bridges are usually supported by pile foundations that are submerged in water and embedded into saturated soils. Such sites have been reported susceptible to scour hazard and probably liquefied under strong earthquakes. Existing studies on seismic response analyses of such bridges often ignore the influence of water-induced hydrodynamic effect. This study assesses quantitative impacts of the hydrodynamic effect on seismic responses of coastal highway bridges under scour and liquefaction potential in a probabilistic manner. A coupled soil-bridge finite element model that represents typical coastal highway bridges is excited by two sets of ground motion records that represent two seismic design levels (i.e., low versus high in terms of 10%-50 years versus 2%-50 years). Modeled by the added mass method, the hydrodynamic effect on responses of bridge key components including the bearing deformation, column curvature, and pile curvature is systematically quantified for scenarios with and without liquefaction across different scour depths. It is found that the influence of hydrodynamic effect becomes more noticeable with the increase of scour depths. Nevertheless, it has minor influence on the bearing deformation and column curvature (i.e., percentage changes of the responses are within 5%), regardless of the liquefiable or nonliquefiable scenario under the low or high seismic design level. As for the pile curvature, the hydrodynamic effect under the low seismic design level may remarkably increase the response by as large as 15%–20%, whereas under the high seismic design level, it has ignorable influence on the pile curvature.

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