Inspection and Evaluation on Prestressing Tendon Force for PC Bridge

2011 ◽  
Vol 243-249 ◽  
pp. 1893-1896
Author(s):  
Qi Guo
Keyword(s):  
Large Scale ◽  
Evaluation Model ◽  
Structural Safety ◽  
Beam Model ◽  
Prestress Losses ◽  
Long Span ◽  
Prestressing Force ◽  
Loss Method ◽  
Prestressing Loss ◽  
Current Code

Being the most critical component among long-span PC bridges, prestress steel tendon’s current condition is closely related to structural safety and durability. For the sake of measuring it exactly to estimate the condition for prestressing reservation practically in service stage, an invented instrument named Stretching Force Tester is applied to monitor the effective prestressing force of strand. The precision of this technology is guaranteed by means of amending analogous boundary condition and minimizing test errors through the tool of double-stage differences. Based on comparatively sophisticated prestressing loss method in current code, an evaluation model on attenuation of effective prestress is built up. By means of obtained stress datum on strand, recognition on two types of nominal coefficients for prestress losses is realized and regularities of practical distribution can be simulated simultaneously. The experimental results of a large-scale beam model demonstrate accuracy and practical utility of the technology.

Chained Analysis of Effective Prestress for Long-Span PC Bridge: Identification, Simulation and Prediction

2011 ◽  
Vol 255-260 ◽  
pp. 891-895
Author(s):  
Qi Guo ◽  
Shuan Hai He
Keyword(s):  
Large Scale ◽  
Evaluation Model ◽  
Structural Safety ◽  
Beam Model ◽  
Long Span ◽  
Prestressing Force ◽  
Structural Deterioration ◽  
Practical Evaluation ◽  
Loss Method ◽  
Prestressing Loss

In order to make much detail and more practical evaluation on structural safety and durability for long-span PC bridges, the condition for prestressing reservation in service stage turns out to be a necessary key index. For the sake of measuring it exactly, an invented instrument named Stretching Force Tester is applied to monitor the effective prestressing force of strand. The precision of this technology is guaranteed by means of amending analogous boundary condition and minimizing test errors through the tool of double-stage differences. Based on comparatively sophisticated prestressing loss method in current code, an evaluation model on attenuation of effective prestress is built up. By means of obtained stress datum on strand, recognition on two types of nominal coefficients for prestress losses is realized and regularities of practical distribution can be simulated simultaneously. The experimental results of a large-scale beam model show that the relative error for cable tension force between test value and standard one is able to meet the needs of engineering use and general principle for effective prestress can be demonstrated. Therefore, it laid the foundation for inspection and evaluation on structural deterioration of existing long-span PC bridges.

scholarly journals Analysis of Short-Term Prestress Losses in Post-tensioned Structures Using Smart Strands

2022 ◽  
Vol 16 (1) ◽  
Author(s):  
Sang-Hyun Kim ◽  
Sung Yong Park ◽  
Sung Tae Kim ◽  
Se-Jin Jeon
Keyword(s):  
Prestressed Concrete ◽  
General Assumption ◽  
Design Parameters ◽  
Short Term ◽  
Prestress Losses ◽  
Predictive Equations ◽  
Girder Bridges ◽  
Long Span ◽  
Prestressing Force ◽  
Study Results

AbstractThe proper estimation of prestressing force (PF) distribution is critical to ensure the safety and serviceability of prestressed concrete (PSC) structures. Although the PF distribution can be theoretically calculated based on certain predictive equations, the resulting accuracy of the theoretical PF needs to be further validated by comparison with reliable test data. Therefore, a Smart Strand with fiber optic sensors embedded in a core wire was developed and applied to a full-scale specimen and two long-span PSC girder bridges in this study. The variation in PF distribution during tensioning and anchoring was measured using the Smart Strand and was analyzed by comparison with the theoretical distribution calculated using the predictive equations for short-term prestress losses. In particular, the provisions for anchorage seating loss and elastic shortening loss were reviewed and possible improvements were proposed. A new method to estimate the amount of anchorage slip based on real PF distributions revealed that the general assumption of 3–6-mm slip falls within a reasonable range. Finally, the sensitivity of the PF distribution to a few of the variables included in the equation of the elastic shortening loss was examined. The study results confirmed that the developed Smart Strand can be used to improve the design parameters or equations in PSC structures by overcoming the drawbacks of conventional sensing technologies.

Monitor and Control on Effective Prestress of Typical Tendons for Long-Span Continuous Rigid Frame Bridge

2011 ◽  
Vol 368-373 ◽  
pp. 1997-2000
Author(s):  
Qi Guo ◽  
Shuan Hai He ◽  
Qing Ning Li
Keyword(s):  
Structural Safety ◽  
Prestress Losses ◽  
Structural Formation ◽  
Geometric Patterns ◽  
Long Span ◽  
Continuous Rigid Frame Bridge ◽  
Rigid Frame ◽  
Prestressed Reinforcement ◽  
Rigid Frame Bridge ◽  
And Control

In order to make much detail monitor and more practical evaluation on structural safety and durability for long-span continuous rigid frame bridge, the condition for prestressing reservation in service stage turns out to be a necessary key index. By means of obtained stress value on prestressing tendons, discrimination on subordinated mode and recognition on nominal coefficients of prestress losses are implemented. Furthermore, unified evaluation on effective prestress of post-tensioned PC bridges are realized at anytime of the whole service life, which include different geometric patterns of prestressed reinforcement, different types of structure and different structural formation systems. Simultaneously, recognition on two types of nominal coefficients for prestress losses is realized and regularities of practical distribution can be simulated. The practical utility of a long-span continuous rigid frame bridge show that the general principle for effective prestress can be demonstrated. Therefore, key parameters for health monitoring on existing long-span continuous rigid frame bridge are provided and the results lay the foundation for further control.

Intelligent Lighting Control System in Large-Scale Sports Competition Venues

2018 ◽  
pp. 172-182 ◽  
Author(s):  
Shengmin CAO
Keyword(s):  
Control System ◽  
Large Scale ◽  
Comprehensive Evaluation ◽  
Evaluation Model ◽  
Fuzzy Comprehensive Evaluation ◽  
Practical Significance ◽  
Lighting Control ◽  
Sports Events ◽  
Planning And Design ◽  
Comprehensive Evaluation Model

This paper mainly studies the application of intelligent lighting control system in different sports events in large sports competition venues. We take the Xiantao Stadium, a large­scale sports competition venue in Zaozhuang City, Shandong Province as an example, to study its intelligent lighting control system. In this paper, the PID (proportion – integral – derivative) incremental control model and the Karatsuba multiplication model are used, and the intelligent lighting control system is designed and implemented by multi­level fuzzy comprehensive evaluation model. Finally, the paper evaluates the actual effect of the intelligent lighting control system. The research shows that the intelligent lighting control system designed in this paper can accurately control the lighting of different sports in large stadiums. The research in this paper has important practical significance for the planning and design of large­scale sports competition venues.

scholarly journals Development and Validation of a Post-Earthquake Safety Assessment System for High-Rise Buildings Using Acceleration Measurements

Mathematics ◽  
2021 ◽  
Vol 9 (15) ◽  
pp. 1758
Author(s):  
Koji Tsuchimoto ◽  
Yasutaka Narazaki ◽  
Billie F. Spencer
Keyword(s):  
Safety Assessment ◽  
Large Scale ◽  
Model Updating ◽  
Safety Evaluation ◽  
Assessment System ◽  
Shaking Table ◽  
Structural Safety ◽  
High Rise ◽  
Steel Building ◽  
Earthquake Safety

After a major seismic event, structural safety inspections by qualified experts are required prior to reoccupying a building and resuming operation. Such manual inspections are generally performed by teams of two or more experts and are time consuming, labor intensive, subjective in nature, and potentially put the lives of the inspectors in danger. The authors reported previously on the system for a rapid post-earthquake safety assessment of buildings using sparse acceleration data. The proposed framework was demonstrated using simulation of a five-story steel building modeled with three-dimensional nonlinear analysis subjected to historical earthquakes. The results confirmed the potential of the proposed approach for rapid safety evaluation of buildings after seismic events. However, experimental validation on large-scale structures is required prior to field implementation. Moreover, an extension to the assessment of high-rise buildings, such as those commonly used for residences and offices in modern cities, is needed. To this end, a 1/3-scale 18-story experimental steel building tested on the shaking table at E-Defense in Japan is considered. The importance of online model updating of the linear building model used to calculate the Damage Sensitive Features (DSFs) during the operation is also discussed. Experimental results confirm the efficacy of the proposed approach for rapid post-earthquake safety evaluation for high-rise buildings. Finally, a cost-benefit analysis with respect to the number of sensors used is presented.

Experimental Research on Erosion of P110 Tubing during Perforating

2014 ◽  
Vol 1073-1076 ◽  
pp. 2244-2247
Author(s):  
Hu Sun ◽  
Zhi Jun Ning ◽  
Zu Wen Wang ◽  
Zhen Li ◽  
Zhi Guo Wang
Keyword(s):  
Weight Loss ◽  
Erosion Rate ◽  
Large Scale ◽  
Guar Gum ◽  
Electrochemical Corrosion ◽  
Low Velocity ◽  
Gas Field ◽  
Weight Loss Method ◽  
Loss Method ◽  
Gas Fields

Erosion is a main failure of tubings and downhole tools in Changqing gas field. It is necessary to evaluate the erosion rate for the safety of tubing and strings. In this paper, the erosion of P110 steel, in the 0.2%wt guar gum fracturing fluid which contains sands, is investigated by weight loss method in the self-made jet experiment device. It is indicated that the erosion rate increases with the increment of slurry velocity exponentially. When the slurry velocity is in low velocity area, the electrochemical corrosion of dissolved oxygen dominates in erosion mechanism; when slurry velocity increases into middle velocity area, the weight loss is controlled by the synergism of corrosion-erosion; and when the slurry velocity increases into high velocity area, the weight loss rate is dominantly depended on erosion of particles. The results can provide guidelines for large-scale fracturing work of Changqing gas fields.

Quantification of Effects of Ridge and Valley Topography on the Rayleigh Wave Characteristics

2018 ◽  
Vol 12 (03) ◽  
pp. 1850007 ◽  
Author(s):  
J. P. Narayan ◽  
A. Kumar
Keyword(s):  
Rayleigh Wave ◽  
Rayleigh Waves ◽  
Large Scale ◽  
Research Work ◽  
Vertical Component ◽  
Staggered Grid ◽  
Long Span ◽  
Shape Ratio ◽  
Day By Day ◽  
Ridge And Valley

The effects of ridge and valley on the characteristics of Rayleigh waves are presented in this paper. The research work carried out has been stimulated by the day by day increase of long-span structures in the hilly areas which are largely affected by the spatial variability in ground motion caused by the high-frequency Rayleigh waves. The Rayleigh wave responses of the considered triangular and elliptical ridge and valley models were computed using a fourth-order accurate staggered-grid viscoelastic P-SV wave finite-difference (FD) program. The simulated results revealed very large amplification of the horizontal component and de-amplification of the vertical component of Rayleigh wave at the top of a triangular ridge and de-amplification of both the components at the base of the triangular valley. The observed amplification of both the components of Rayleigh wave in front of elliptical valley was larger than triangular valley models. A splitting of the Rayleigh wave wavelet was inferred after interaction with ridge and valley. It is concluded that the large-scale topography acts as a natural insulator for the surface waves and the insulating capacity of the valley is more than that of a ridge. This insulation phenomenon is arising due to the reflection, diffraction and splitting of the surface wave while moving across the topography. It is concluded that insulating potential of the topography for the Rayleigh waves largely depends on their shape and shape-ratio.

scholarly journals GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey III: South Galactic Pole data release

2021 ◽  
Vol 38 ◽  
Author(s):  
T. M. O. Franzen ◽  
N. Hurley-Walker ◽  
S. V. White ◽  
P. J. Hancock ◽  
N. Seymour ◽  
...  
Keyword(s):  
Large Scale ◽  
Angular Resolution ◽  
Beam Model ◽  
Spectral Variability ◽  
Extragalactic Source ◽  
Automated Algorithm ◽  
Data Release ◽  
Murchison Widefield Array ◽  
Source Populations ◽  
One Year

Abstract We present the South Galactic Pole (SGP) data release from the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) survey. These data combine both years of GLEAM observations at 72–231 MHz conducted with the Murchison Widefield Array (MWA) and cover an area of 5 113 $\mathrm{deg}^{2}$ centred on the SGP at $20^{\mathrm{h}} 40^{\mathrm{m}} < \mathrm{RA} < 05^{\mathrm{h}} 04^{\mathrm{m}}$ and $-48^{\circ} < \mathrm{Dec} < -2^{\circ} $ . At 216 MHz, the typical rms noise is ${\approx}5$ mJy beam–1 and the angular resolution ${\approx}2$ arcmin. The source catalogue contains a total of 108 851 components above $5\sigma$ , of which 77% have measured spectral indices between 72 and 231 MHz. Improvements to the data reduction in this release include the use of the GLEAM Extragalactic catalogue as a sky model to calibrate the data, a more efficient and automated algorithm to deconvolve the snapshot images, and a more accurate primary beam model to correct the flux scale. This data release enables more sensitive large-scale studies of extragalactic source populations as well as spectral variability studies on a one-year timescale.

scholarly journals Automated Visual Recognizability Evaluation of Traffic Sign Based on 3D LiDAR Point Clouds

2019 ◽  
Vol 11 (12) ◽  
pp. 1453 ◽  
Author(s):  
Shanxin Zhang ◽  
Cheng Wang ◽  
Lili Lin ◽  
Chenglu Wen ◽  
Chenhui Yang ◽  
...  
Keyword(s):  
Traffic Safety ◽  
Laser Scanning ◽  
Large Scale ◽  
Evaluation Method ◽  
Evaluation Model ◽  
Point Clouds ◽  
Traffic Sign ◽  
Traffic Signs ◽  
3D Point Clouds ◽  
Traffic Environment

Maintaining the high visual recognizability of traffic signs for traffic safety is a key matter for road network management. Mobile Laser Scanning (MLS) systems provide efficient way of 3D measurement over large-scale traffic environment. This paper presents a quantitative visual recognizability evaluation method for traffic signs in large-scale traffic environment based on traffic recognition theory and MLS 3D point clouds. We first propose the Visibility Evaluation Model (VEM) to quantitatively describe the visibility of traffic sign from any given viewpoint, then we proposed the concept of visual recognizability field and Traffic Sign Visual Recognizability Evaluation Model (TSVREM) to measure the visual recognizability of a traffic sign. Finally, we present an automatic TSVREM calculation algorithm for MLS 3D point clouds. Experimental results on real MLS 3D point clouds show that the proposed method is feasible and efficient.

An efficient Cholesky decomposition and applications for the simulation of large-scale random wind velocity fields

2018 ◽  
Vol 22 (6) ◽  
pp. 1255-1265 ◽  
Author(s):  
Yongle Li ◽  
Chuanjin Yu ◽  
Xingyu Chen ◽  
Xinyu Xu ◽  
Koffi Togbenou ◽  
...  
Keyword(s):  
Wind Velocity ◽  
Large Scale ◽  
Spectral Representation ◽  
Cholesky Decomposition ◽  
Velocity Fields ◽  
Data Driven ◽  
Long Span Bridges ◽  
Long Span ◽  
Spectral Representation Method ◽  
Representation Method

A growing number of long-span bridges are under construction across straits or through valleys, where the wind characteristics are complex and inhomogeneous. The simulation of inhomogeneous random wind velocity fields on such long-span bridges with the spectral representation method will require significant computation resources due to the time-consuming issues associated with the Cholesky decomposition of the power spectrum density matrixes. In order to improve the efficiency of the decomposition, a novel and efficient formulation of the Cholesky decomposition, called “Band-Limited Cholesky decomposition,” is proposed and corresponding simulation schemes are suggested. The key idea is to convert the coherence matrixes into band matrixes whose decomposition requires less computational cost and storage. Subsequently, each decomposed coherence matrix is also a band matrix with high sparsity. As the zero-valued elements have no contribution to the simulation calculation, the proposed method is further expedited by limiting the calculation to the non-zero elements only. The proposed methods are data-driven ones, which can be applicable broadly for simulating many complicated large-scale random wind velocity fields, especially for the inhomogeneous ones. Through the data-driven strategies presented in the study, a numerical example involving inhomogeneous random wind velocity field simulation on a long-span bridge is performed. Compared to the traditional spectral representation method, the simulation results are with high accuracy and the entire simulation procedure is about 2.5 times faster by the proposed method for the simulation of one hundred wind velocity processes.

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