Damage Assessment of a continuous Hollow Core Deck Bridge subjected to ASR

2019 ◽  
Author(s):  
Konstantinos Tsiotsias ◽  
S. J. Pantazopoulou ◽  
Dimitrios Nikolaidis
Keyword(s):  
Synergistic Effects ◽  
Hollow Core ◽  
Element Analysis ◽  
Lower Face ◽  
Bridge Rehabilitation ◽  
Structural Capacity ◽  
Fine Aggregates ◽  
Chemically Induced ◽  
Extent Of Damage ◽  
Longitudinal Cracks

<p>An existing highway overpass located on a major motorway in Europe is examined on account of extensive longitudinal cracking on the lower face and sides of the deck, and signs of sustained damage in the piers. Material analysis reports have validated the existence of ASR activity in fine aggregates. The deck comprises a well reinforced hollow-core prestressed system, however longitudinal cracks penetrate to the interior of the hollow cores. The extent of damage is heavy considering that the laboratory values for free ASR expansion are below the threshold limits, suggesting that there may be underlying structural causes related to the response of the deck under traffic. Objective of the study is to interpret the reported damage, reproduce computationally the mechanics that led to the observed crack pattern and assess the residual structural capacity of the bridge. Detailed nonlinear finite element analysis is conducted to evaluate the structure and study the synergistic effects of structural demands, along with time-dependent phenomena and chemically induced expansion. The paper presents the numerical modeling and mechanistic evaluation of the findings through sensitivity analysis of various scenarios considered to reproduce the state of damage and to assess the effectiveness of various retrofitting strategies considered for bridge rehabilitation.</p>

scholarly journals Characteristic Analysis and Structural Design of Hollow-Core Photonic Crystal Fibers with Band Gap Cladding Structures

Sensors ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 284
Author(s):  
Bowei Wan ◽  
Lianqing Zhu ◽  
Xin Ma ◽  
Tianshu Li ◽  
Jian Zhang
Keyword(s):  
Photonic Crystal ◽  
Band Gap ◽  
Photonic Crystal Fibers ◽  
Relative Sensitivity ◽  
Confinement Loss ◽  
Hollow Core ◽  
Characteristic Analysis ◽  
Element Analysis ◽  
The Core ◽  
Crystal Fibers

Due to their flexible structure and excellent optical characteristics hollow-core photonic crystal fibers (HC-PCFs) are used in many fields, such as active optical devices, communications, and optical fiber sensing. In this paper, to analyze the characteristics of HC-PCFs, we carried out finite element analysis and analyzed the design for the band gap cladding structure of HC-PCFs. First, the characteristics of HC19-1550 and HC-1550-02 in the C-band were simulated. Subsequently, the structural optimization of the seven-cell HC-1550-02 and variations in characteristics of the optimized HC-1550-02 in the wavelength range 1250–1850 nm were investigated. The simulation results revealed that the optimal number of cladding layers is eight, the optimal core radius is 1.8 times the spacing of adjacent air holes, and the optimal-relative thickness of the core quartz-ring is 2.0. In addition, the low confinement loss bandwidth of the optimized structure is 225 nm. Under the transmission bandwidth of the optimized structure, the core optical power is above 98%, the confinement loss is below 9.0 × 10−3 dB/m, the variation range of the effective mode field area does not exceed 10 μm2, and the relative sensitivity is above 0.9570. The designed sensor exhibits an ultra-high relative sensitivity and almost zero confinement loss, making it highly suitable for high-sensitivity gas or liquid sensing.

Longitudinal Joint Performance of a Concrete Hollow Core Slab Bridge

2018 ◽  
Vol 2672 (41) ◽  
pp. 196-206 ◽  
Author(s):  
Diego Maria Barbieri ◽  
Yuechi Chen ◽  
Enrico Mazzarolo ◽  
Bruno Briseghella ◽  
Angelo Marcello Tarantino
Keyword(s):  
Finite Element ◽  
Design Method ◽  
Concrete Strength ◽  
Element Model ◽  
Active Role ◽  
Hollow Core ◽  
Hinge Joint ◽  
Longitudinal Joint ◽  
Hollow Core Slab ◽  
Longitudinal Cracks

Hollow core slab bridges are constructed by placing prefabricated or prestressed box beams adjacent to each other, grouting the small longitudinal space (hinge-joint) between the slabs and casting a reinforced concrete deck. The longitudinal cracking appearing at hinge-joint locations leads to a premature deterioration of the deck. This paper presents a theoretical and experimental study of a hollow core slab bridge composed of three beams and a cast-in-place deck. A real-size specimen was built according to Chinese code specifications. The behavior of the longitudinal joints was investigated by applying the standard vehicle load. The tests do not highlight any longitudinal cracks. A finite element model was created from the experimental data. A finite element parametric analysis revealed some practical design indications regarding the following inputs: deck thickness, concrete strength, and hinge-joint steel bars. Furthermore, these analyses testify that C-shape and X-shape stirrups do not play an active role in preventing the joint longitudinal cracks. This research confirms the reliability of the design method, at least for static loads, while further studies are needed to investigate the effect of both periodical loadings and different temperatures on upper and lower surfaces of the beams.

Finite Element Analysis of SiCp/Al Model of Unit Cell during Ultrasonic Vibration Scratching

2016 ◽  
Vol 693 ◽  
pp. 1022-1029
Author(s):  
G.Q. Liang ◽  
Ping Fa Feng ◽  
Jian Fu Zhang
Keyword(s):  
Finite Element ◽  
Maximum Amplitude ◽  
Element Model ◽  
Ultrasonic Frequency ◽  
Frequency Range ◽  
Element Analysis ◽  
Scale Modeling ◽  
Sic Particles ◽  
Significant Damage ◽  
Extent Of Damage

In this paper, finite element model of SiCp /Al single cell body and single diamond particles were established by cross-scale modeling method. The results shows that the extent of damage of SiC particles increased with the increase of amplitude and frequency; The integrity of SiC particles are still better under the ultrasonic frequency 20000 Hz and the maximum amplitude 5um,so the optimal frequency range of ultrasonic scratch is (20000-30000)Hz. As for 22000 Hz, the integrity of SiC particles was better under the amplitude 4um,while the SiC particles have a significant damage in the border area under the amplitude 5um,so the best frequency and amplitude for ultrasonic scratches are: 22000 Hz and 4 um.

Hollow core–shell ZnO@ZIF-8 on carbon cloth for flexible supercapacitors with ultrahigh areal capacitance

2019 ◽  
Vol 55 (12) ◽  
pp. 1746-1749 ◽  
Author(s):  
Xiao-Man Cao ◽  
Zheng-Bo Han
Keyword(s):  
Synergistic Effects ◽  
Growth Strategy ◽  
Core Shell ◽  
Carbon Cloth ◽  
Hollow Core ◽  
Areal Capacitance ◽  
Unique Structure ◽  
Flexible Supercapacitors ◽  
Good Cycling Stability

A hollow core–shell hetero-structured electrode (PANI/ZnO@ZIF-8-CC) is designed and synthesized via a ‘root-etch-wrap’ process for flexible supercapacitors. The unique structure, in situ growth strategy and synergistic effects endow PANI/ZnO@ZIF-8-CC with ultrahigh areal capacitance and good cycling stability.

Analysis on the Development Trend of the Longitudinal Cracks During Tunnels Construction Based on the Strength Reduction Theory

2011 ◽  
Vol 368-373 ◽  
pp. 2949-2954
Author(s):  
Xin Qiang Gao ◽  
Gang Rong ◽  
Yong Quan Zhu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Development Trend ◽  
Strength Reduction ◽  
Reduction Theory ◽  
Element Analysis ◽  
Section Method ◽  
Cut Method ◽  
Longitudinal Cracks ◽  
The Development Trend

This article used the elastic-plastic finite element analysis method based on strength reduction theory and researched the regularity of longitudinal formation cracks during the loess tunnel construction. It analyzed the development trend of the crack dips and the distance between the surface crack and the tunnel center by different depth conditions when using the full section method and the bench cut method during the construction. From that it can get the boundary value of tunnel depth that the longitudinal crack can reach the ground. The result shows that: (1) Through the finite element analysis of the continuum structural model, it is feasible and effective to use the method, which is based on the area including the shear stress greater than the cohesive stress, the mutant horizontal displacement, and the change trend of the vertical displacement, to analyze the trend and the scope of longitudinal cracks after the excavation of the loess tunnels. (2) When using the full section method, the longitudinal cracks can reach the ground as long as the buried depth is less than 50m.With the increase of the buried depth, both of the depth of the cracks and the distance between the cracks and the tunnel center are all increased and the crack dips are changeable whose range is 56º~67º. However when the buried depth is more than 50m, the cracks can’t reach the ground and develop from the vault to the ground. The slip tendency near the ground is diminished. With the increase of the buried depth, the dips get larger, but the distance between the cracks and the tunnel center and the crack depth are invariable. (3) When using the-bench-cut method, the development trend of the formation crack is similar to that of the full section method. The cracks can reach the ground when the depth is less than 40m, and the range of the cracks is 56º~62º, or else the cracks can’t reach the ground. (4) From controlling the surface cracks, the bench cut method is superior to the full section method.

In-Service Repair of Flexible Riser Damage Experience With the North Sea Galley Field

2007 ◽  
Author(s):  
Keith Anderson ◽  
Ian MacLeod ◽  
Brian O’Keeffe
Keyword(s):  
Structural Damage ◽  
Corrosion Damage ◽  
Flexible Pipe ◽  
The North ◽  
Structural Capacity ◽  
The North Sea ◽  
Fit For Purpose ◽  
Potential Damage ◽  
Extent Of Damage ◽  
Gas Volume

Routine GVI of the Galley riser system indicated potential damage to the Gas Export riser. This was observed as a steady stream of gas bubbles emanating from within an inverted bellmouth used to constrain riser motion at the Floating Production Facility (FPF) pontoon level. The vented gas volume was consistent with permeated gas rates from the annulus, an indicator of damage to the external sheath of the riser. The inverted bellmouth negated inspection of the riser within, hence the cause of the damage could not be ascertained. To determine the condition of the structure the riser was isolated and raised to allow inspection of the damaged section. This inspection found structural damage to the outer layers of the flexible pipe including corrosion damage of the outer tensile armour wires reducing the structural capacity of the riser. The extent of damage instigated a multi-company, multi-disciplinary team investigation and implementation of unique remedial measures to ensure fit for purpose operations for the remainder of field life. Implementation of the permanent remedial works was performed and successfully completed with reintroduction of the risers to permanent service in January 2006. This paper describes in detail the novel and unique techniques used to repair and re-commission the damaged riser.

scholarly journals Flexural Behavior of Reinforced Concrete Beams Retrofitted with Modularized Steel Plates

2021 ◽  
Vol 11 (5) ◽  
pp. 2348
Author(s):  
Min Sook Kim ◽  
Young Hak Lee
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Load Capacity ◽  
Maximum Load ◽  
Reinforced Concrete Beams ◽  
Steel Plates ◽  
Flexural Behavior ◽  
Element Analysis ◽  
Flexural Performance ◽  
Structural Capacity

Many structural retrofitting methods tend to only focus on how to improve the strength and ductility of structural members. It is necessary for developing retrofitting strategy to consider not only upgrading the capacity but also achieving rapid and economical construction. In this paper, a new retrofitting details and technique is proposed to improve structural capacity and constructability for retrofitting reinforced concrete beams. The components of retrofitting are prefabricated, and the components are quickly assembled using bolts and chemical anchors on site. The details of modularized steel plates for retrofitting have been chosen based on the finite element analysis. To evaluate the structural performance of concrete beams retrofitted with the proposed details, five concrete beams with and without retrofitting were tested. The proposed retrofitting method significantly increased both the maximum load capacity and ductility of reinforced concrete beams. The test results showed that the flexural performance of the existing reinforced concrete beams increased by 3 times, the ductility by 2.5 times, and the energy dissipation capacity by 7 times.

scholarly journals Inspection and Assessment of Masonry Arch Bridges: Ivanjica Case Study

2021 ◽  
Vol 13 (23) ◽  
pp. 13363
Author(s):  
Neda M. Sokolović ◽  
Milica Petrović ◽  
Ana Kontić ◽  
Suzana Koprivica ◽  
Nenad Šekularac
Keyword(s):  
Collapse Mechanism ◽  
Mechanism Analysis ◽  
Structural Behaviour ◽  
Masonry Arch ◽  
Element Analysis ◽  
Historical Structures ◽  
3D Simulation Model ◽  
Arch Bridges ◽  
Longitudinal Cracks

The importance of masonry arch bridges as a traffic network element calls for a thorough analysis focused on both structural stability and loading capacity of these historical structures, considering the usage of these bridges in contemporary traffic conditions. This paper focuses on the analysis of longitudinal cracks in a single span masonry arch bridge to evaluate its influence on structural behaviour of the system. As longitudinal cracks do not necessarily present an inevitable collapse mechanism, analysis of the causes is crucial for evaluating the serviceability and functionality of the bridge investigated. The methodology is based on the following: literature review, observation of the stone bridge in Ivanjica, geological testing of the site, geophysical testing of the bridge, laboratory testing of mechanical characteristics of stone used for the bridge construction and biological analysis of the samples of implemented materials on the bridge. Finite element analysis of the bridge was conducted to define the causes of the longitudinal cracks. The 3D simulation model was based on the data collected through observation and experimental analysis. This paper provides extensive research on a single span masonry bridge, examining how different deterioration mechanisms, in conjunction, can lead to the appearance of cracks in masonry arch bridges and provide remedial measures accordingly.

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