scholarly journals Estimation on Embedment Length of Anchor Bolt inside Concrete Using Equation for Arrival Time and Shortest Time Path of Ultrasonic Pulse

2020 ◽  
Vol 10 (24) ◽  
pp. 8848
Author(s):  
Chiwon Song ◽  
Young Jin Kim ◽  
Chang Beck Cho ◽  
Won Jong Chin ◽  
Kwang-Yeun Park
Keyword(s):  
Inverse Analysis ◽  
Seismic Isolation ◽  
Arrival Time ◽  
Critical Role ◽  
Ultrasonic Pulse ◽  
Concrete Cover ◽  
P Wave ◽  
Embedment Depth ◽  
Anchor Bolt ◽  
Anchor Bolts

The bearings or the seismic isolation bearings that play a critical role in bridge structures are fixed to the substructure by anchor bolts. However, the embedment depth of the constructed anchor bolts does often not reach the designed one and may lead to safety issues. The present study proposes an ultrasonic non-destructive testing (NDT) method to verify the embedment depth of the anchor bolts installed on bridges in-service. The P-wave of 50–100 kHz that is usually used in the NDT of concrete was transmitted from the head of the anchor bolt and its arrival time on the concrete cover was measured. The shortest arrival time of the ultrasonic pulse and the corresponding path were then analyzed to formulate their relationship and obtain the distance traveled by the ultrasonic pulse along the anchor by inverse analysis using the equation error estimation. The instability occurring in the inverse analysis is settled by regularization. Finally, the embedment depth of the anchor bolt can be estimated by the analysis of the graph plotting the position of the ultrasonic transmitter and the distance traveled by the pulse along the anchor. The proposed method is validated numerically and experimentally. The method is expected to contribute to the NDT of civil structures by making it possible to estimate the embedment depth of anchor bolts by the means of ultrasonic transducers using P-waves of 50–100 kHz.

A Numerical Study on the Pull-Out Strengths of Anchor Bolts Embedded in Concrete Using the Smoothed Particle Hydrodynamics Method

2016 ◽  
Vol 711 ◽  
pp. 1111-1117 ◽  
Author(s):  
Yoshimi Sonoda
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Failure Modes ◽  
Numerical Study ◽  
Failure Process ◽  
Embedment Depth ◽  
Anchor Bolt ◽  
Pull Out ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Anchor Bolts

The strength of an anchor bolt in concrete structure under pull-out load is usually designed by three possible failure modes such as fracture of anchor bolt, cone failure of concrete and bond failure between anchor bolt and concrete. In general, the design load is considered the smallest load corresponding to the aforementioned failure mechanisms. However, unexpected failure often occurs in the anchorage zone due to the complex failure or the change of failure condition. Therefore, it is important to develop the accurate analysis method of ultimate load bearing capacity of the anchor bolt. In this study, we conducted an analytical study using Adaptive Smoothed Particle Hydrodynamics (ASPH) in order to simulate the failure process of anchorage zone and discussed the effect of embedment depth of anchor bolts on their ultimate strength.

scholarly journals An Analytical Study on the Pull-Out Strength of Anchor Bolts Embedded in Concrete Members by SPH Method

2021 ◽  
Vol 11 (18) ◽  
pp. 8526
Author(s):  
Chi Lu ◽  
Yoshimi Sonoda
Keyword(s):  
Load Capacity ◽  
Seismic Retrofitting ◽  
Embedment Depth ◽  
Structural Members ◽  
Sph Method ◽  
Anchor Bolt ◽  
Failure Patterns ◽  
Pull Out ◽  
Anchor Bolts ◽  
Pull Out Strength

As an important method for connecting structural members, anchor bolts have been installed in many situations. Therefore, accurate evaluation of the pull-out strength of anchor bolts has always been an important issue, considering the complicated actual installation conditions and the problem of aging deterioration of the structural members. In general, the patterns of pull-out failure of anchor bolts can be classified into three types: adhesion failure, cone failure, and bolt break. However, it sometimes shows a mixed fracture pattern, and it is not always easy to predict the accurate pull-out strength. In this study, we attempted to evaluate the pull-out strength of anchor bolts under various installation conditions using SPH, which can analyze the crack growth process in the concrete. In particular, the anchor bolt-concrete interface model was introduced to SPH analysis in order to consider the bond failure, and it was confirmed that various failure patterns and the load capacity could be predicted by proposed SPH method. After that, the influence of several parameters, such as bond stress limit, anchor bolt diameter, and the anchor bolt embedment depth on the failure patterns and the load capacity, were investigated by numerical calculation. Furthermore, several useful suggestions on the pull-out strength of anchor bolts under improper installation conditions, such as the ends of members for the purpose of seismic retrofitting, are presented.

Assessment of ambulance services performance by queuing theory, at the Center for Disaster and Emergency Management: A descriptive-analytical study

2021 ◽  
Vol 19 (5) ◽  
pp. 469-478
Author(s):  
Mehdi Nasr Isfahani, MD ◽  
Azar Niknam, PhD Student ◽  
Mahoobeh Doosti-Irani, PhD Student
Keyword(s):  
Call Center ◽  
Queuing Theory ◽  
Analytical Study ◽  
Arrival Time ◽  
Statistical Data ◽  
Average Duration ◽  
Critical Role ◽  
International Standards ◽  
Admission Process ◽  
The City

Background: The emergency departments of the hospitals and emergency medical services (EMSs) centers have a critical role for providing urgent medical care for patients. The statistical data of the present study were provided by the EMS headquarters of the city of Isfahan, from August to November 2017. Results: The findings showed that on average, 210 missions were accomplished each day by the emergency call center, with an average duration of about 53 minutes, for each mission. In addition, the average time for response time (the time between a call and dispatch of the ambulance) was less than 3 minutes, and the average time for arrival time (the time between request of ambulance and the arrival to the scene) was 8.1 minutes. Adequacy of current number of ambulances and staff is evaluated.Conclusion: Considering an average of 8.1 minutes for arrival time, we conclude that the EMS of Isfahan is within an acceptable range, compared to the international standards. In fact, it is shown that the infrastructures of EMS system including ambulance fleets, staff, and equipment are sufficient, and as an effective step for reducing the total time of the mission, the EMS has to operate seamlessly with the patient’s admission process in hospitals. Information such as workload hours, availability of resources and staff, etc. ought to be shared between the EMS and the hospital.

scholarly journals Analytical Model for Predicting the UCS from P-Wave Velocity, Density, and Porosity on Saturated Limestone

2019 ◽  
Vol 9 (23) ◽  
pp. 5265 ◽  
Author(s):  
González ◽  
Saldaña ◽  
Arzúa
Keyword(s):  
Wave Velocity ◽  
Predictive Models ◽  
Laboratory Tests ◽  
Ultrasonic Pulse ◽  
P Wave ◽  
Test Results ◽  
Regression Analyses ◽  
P Wave Velocity ◽  
Dry Conditions ◽  
Engineering Projects

Rock mechanics and rock engineering projects require determining, among other parameters, the uniaxial compressive strength (UCS) of rock. For such a purpose, it is not uncommon to perform ultrasonic pulse laboratory tests. Many researchers have found experimental relationships between strength and P-wave velocity, but these relationships are based mainly on dry conditions and without considering any other physical or chemical characteristics of the studied rock. Specifically, for limestone, there are 11 correlations reported in the literature, eight of which are simple and the remaining three are multiple, and, among the latter, only two of them consider the saturation. In order to evaluate the combined effect of P-wave velocity, density, and porosity on the UCS of saturated limestone, simple and multiple regression analyses were carried out on the test results of 13 saturated limestone specimens to determine the parameters of both previously mentioned predictive models. The results showed that density is not correlated with strength.

Time-Arrival Location of Seismic P-Wave Based on Wavelet Transform

2013 ◽  
Vol 722 ◽  
pp. 239-243 ◽  
Author(s):  
Xiao Hong Liu
Keyword(s):  
Wavelet Transform ◽  
Data Analysis ◽  
Standard Deviation ◽  
Arrival Time ◽  
Research Field ◽  
P Wave ◽  
Seismic Exploration ◽  
First Arrival ◽  
Modulus Maxima ◽  
Foundational Problem

The automatic pick of seismic first arrivals is a foundational problem in Seismic Exploration. Picking the first arrival of P-wave is an important problem in the seismic research field. The modulus maxima of wavelet transform is a useful method for picking up the singularities of function. For applying the modulus maxima method to investigate the arrival time of P-wave, it is necessary to eliminate the influence of random factors. Based on standard deviation, we present a method to reduce the influence of random factors. Then we get an approach to detect the arrival time of P-wave by means of window energy ratio factors. The results of data analysis indicate that our method is more effective.

scholarly journals The Measurement of P-, S-, and R-Wave Velocities to Evaluate the Condition of Reinforced and Prestressed Concrete Slabs

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Young Hak Lee ◽  
Taekeun Oh
Keyword(s):  
Prestressed Concrete ◽  
Goodness Of Fit ◽  
Concrete Structures ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Experimental Results ◽  
P Wave ◽  
Concrete Slabs ◽  
Goodness Of Fit Test ◽  
Wave Velocities

The traditional P-wave ultrasonic measurement has been used for the condition assessment of general reinforced concrete structures for a long time, but the effects of prestressing applied to concrete structures such as long-span buildings and bridges on ultrasonic pulse velocity have not been studied clearly. Therefore, this study analyzed the statistical distribution of P-wave ultrasonic pulse velocities in reinforced and prestressed concrete slabs of 3000 × 3000 mm with a thickness of 250 mm. In addition, we measured S- and R-waves to identify experimental consistency by statistical analysis using the Kolmogorov-Smirnov goodness-of-fit test. The experimental results show that the P-, S-, and R-wave velocities increased slightly (2-3%) when prestressing was applied. As expected, the S- and R-wave measurements show better statistical reliability and potential for in situ evaluation than the P-wave because they are less sensitive to confinement and boundary conditions. The experimental results in this study can be used when assessing the condition of prestressed concrete structures through the velocities of elastic waves.

Frame moduli of unconsolidated sands and sandstones

Geophysics ◽  
1994 ◽  
Vol 59 (9) ◽  
pp. 1352-1361 ◽  
Author(s):  
James W. Spencer ◽  
Michael E. Cates ◽  
Don D. Thompson
Keyword(s):  
Poisson’S Ratio ◽  
Empirical Relation ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
P Wave ◽  
Poisson's Ratio ◽  
Unconsolidated Sands ◽  
Seismic Amplitude ◽  
Seismic Frequencies

In this study, we investigate the elastic moduli of the empty grain framework (the “frame” moduli) in unconsolidated sands and consolidated sandstones. The work was done to improve the interpretation of seismic amplitude anomalies and amplitude variations with offset (AVO) associated with hydrocarbon reservoirs. We developed a laboratory apparatus to measure the frame Poisson’s ratio and Young’s modulus of unconsolidated sands at seismic frequencies (0.2 to 155 Hz) in samples approximately 11 cm long. We used ultrasonic pulse velocity measurements to measure the frame moduli of consolidated sandstones. We found that the correlation coefficient between the frame Poisson’s ratio [Formula: see text] and the mineral Poisson’s ratio [Formula: see text] is 0.84 in consolidated sandstones and only 0.28 in unconsolidated sands. The range of [Formula: see text] values in unconsolidated sands is 0.115 to 0.237 (mean = 0.187, standard deviation = 0.030), and [Formula: see text] cannot be estimated without core or log analyses. Frame moduli analyses of core samples can be used to calibrate the interpretation of seismic amplitude anomalies and AVO effects. For use in areas without core or log analyses, we developed an empirical relation that can be used to estimate [Formula: see text] in unconsolidated sands and sandstones from [Formula: see text] and the frame P‐wave modulus.

Joint microseismic event location and anisotropic velocity inversion with the cross double-difference method using downhole microseismic data

Geophysics ◽  
2020 ◽  
Vol 85 (3) ◽  
pp. KS63-KS73
Author(s):  
Yangyang Ma ◽  
Congcong Yuan ◽  
Jie Zhang
Keyword(s):  
Arrival Time ◽  
Velocity Model ◽  
P Wave ◽  
Double Difference ◽  
S Wave ◽  
Arrival Times ◽  
Monitoring Well ◽  
The Cross ◽  
Microseismic Event ◽  
Wave Arrival

We have applied the cross double-difference (CDD) method to simultaneously determine the microseismic event locations and five Thomsen parameters in vertically layered transversely isotropic media using data from a single vertical monitoring well. Different from the double-difference (DD) method, the CDD method uses the cross-traveltime difference between the S-wave arrival time of one event and the P-wave arrival time of another event. The CDD method can improve the accuracy of the absolute locations and maintain the accuracy of the relative locations because it contains more absolute information than the DD method. We calculate the arrival times of the qP, qSV, and SH waves with a horizontal slowness shooting algorithm. The sensitivities of the arrival times with respect to the five Thomsen parameters are derived using the slowness components. The derivations are analytical, without any weak anisotropic approximation. The input data include the cross-differential traveltimes and absolute arrival times, providing better constraints on the anisotropic parameters and event locations. The synthetic example indicates that the method can produce better event locations and anisotropic velocity model. We apply this method to the field data set acquired from a single vertical monitoring well during a hydraulic fracturing process. We further validate the anisotropic velocity model and microseismic event locations by comparing the modeled and observed waveforms. The observed S-wave splitting also supports the inverted anisotropic results.

scholarly journals Comparison of Pigtail with J Anchor Bolt in Normal Concrete

2018 ◽  
Vol 150 ◽  
pp. 03001
Author(s):  
Mohamad Hairi Osman ◽  
Mohamad Nur Mustaqim Abd Shukor ◽  
Suraya Hani Adnan ◽  
Mohamad Luthfi Ahmad Jeni ◽  
Mohd Sufyan Abdullah ◽  
...  
Keyword(s):  
Load Capacity ◽  
Testing Machine ◽  
Tensile Load ◽  
Steel Structure ◽  
Maximum Load ◽  
Anchor Bolt ◽  
Average Value ◽  
Two Samples ◽  
Bending Radius ◽  
Anchor Bolts

Anchor bolts have been used to attach the steel structure of concrete and transfer load into the concrete. Anchor bolts in concrete are to withstand the shear force as they connect steel beams to the reinforced concrete foundations. The research was carried out to increase the understanding and investigating the performance of anchor bolts Pigtail since there is a lack of research on the bolt and to compare it with anchor bolts J which have been widely used by the industry. According to the methodology, testing the tensile load was used in this research to get a maximum load capacity of the anchor bolt in concrete. The sample was embedded in concrete cylinders of 75mm radius and 300mm height. Depths of embedment were 200mm, 230mm, and 260mm. The Universal Testing Machine, UTM was used to test the strength of tensile. 12 samples were used, each type and depth used two samples to get the average value using concrete grade 30. The samples underwent the process of curing for 28 days. The anchor bolts J used a 40mm bending radius and the length of hook was 100mm. Anchor bolts pigtail also used the 10 bending radius with depth of 8mm that have been compressed using 16mm radius rigs with a load of 500kN. Results of the research showed the depth of 260mm for Pigtail almost the same with J 60.529kN and 53.628kN and anchor bolts J were 75.557kN and 76.332kN. Difference of the values was not too far vary when compared with the 200mm and 230mm depths. Each comparison showed the ability of each bolt and anchor bolt failure occurred. Performance of the anchor bolts pigtail can be used on a structure or a higher load at an embedment of 260mm. Embedment of 200mm and 230mm can be used on a lighter load if steel material saving is a priority in every usage.

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