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Estimation of Manning’s Roughness Coefficient Through Calibration Using HEC-RAS Model: A Case Study of Rohri Canal, Pakistan
Shan-e-hyder Soomro,
Caihong Hu,
Muhammad Munir Babar,
Mairaj Hyder Alias Aamir
Issue:
Volume 9, Issue 1, January 2021
Pages:
1-10
Received:
17 October 2020
Accepted:
14 January 2021
Published:
22 January 2021
Abstract: In understanding the hydraulic characteristics of river system flow, the hydraulic simulation models are essential tools. The suitable value of Manning’s roughness coefficient “n” is chosen through method of calibration; i.e., the value which reproduces observed data to an acceptable accuracy. In the present study, the unsteady flow model HEC-RAS is applied to Rohri Canal (upstream Rohri) to estimate value of manning’s coefficient through the procedure. Through a series of systematic. Studies to identify the n values in a hypothetical open channel and a natural stream stretch, several identification procedures based on unconstrained and constrained minimizations are analyzed. However, the decision on what value to adopt is a complex task, especially when dealing with natural water courses due to the various factors that affect this coefficient ‘n’. The data was collected in the period of January (2010) to December (2011), and divided equally into two sets. The first set is for calibration purpose, estimation of (n) and the second set for the verification process of testing the model with actual data to establish its predictability accuracy. Graphical and statistical approaches were used for model calibration and verification. Results show that the manning’s roughness coefficient “n” for Rohri Canal which shows good agreement between observed and computed hydrograph is 0.042.
Abstract: In understanding the hydraulic characteristics of river system flow, the hydraulic simulation models are essential tools. The suitable value of Manning’s roughness coefficient “n” is chosen through method of calibration; i.e., the value which reproduces observed data to an acceptable accuracy. In the present study, the unsteady flow model HEC-RAS i...
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Research for the Detecting Method of Concrete Structure Internal Defects with Spherical Embedded Ultrasonic Transducer
Xingbin Zhang,
Sha Fang,
Hua Rong,
Jingshu Wu,
Guanqiao Zhao
Issue:
Volume 9, Issue 1, January 2021
Pages:
11-17
Received:
20 December 2018
Accepted:
25 February 2019
Published:
10 February 2021
Abstract: As a nondestructive detecting method, ultrasonic detection has been widely adopted in concrete structure detections. This approach would not damage the structural integrity, and could fulfill most of the detecting requirements of various concrete structures. However, for mass concrete and complicated concrete structural elements, there are still many problems of detection to be solved, such as the operating position of detection could not be achieved easily for technicians, especially in some narrow spaces, or the volume of elements might be quite large so that the detecting distance is far beyond the effective detecting distance of traditional transducers. After researching the technical performances of traditional ultrasonic transducers and ultrasonic detecting method, a brand new type of ultrasonic transducer adopted spherical piezoelectric ceramic chips has been developed. The transducer could be embedded inside concrete structure, and motivate or receive ultrasonic signal in all directions pair with external or internal transducers. Testing with the embedded transducers would not be limited by on-site conditions or other enviorenmental conditions. The transducer could be used in realtime systems for monitoring or detecting internal compactness situation of concrete elements. The technical characteristics of spherical transducer have been verified by a series of experiments in laboratory. Moreover, the detecting method with spherical transducer has been proposed, which could be used in the inspection for mass concrete and complicated structural concrete elements. Meanwhile, the appropriate technical schemes for reactor containment of nuclear power plant have been designed and has already been applied in nuclear power plant.
Abstract: As a nondestructive detecting method, ultrasonic detection has been widely adopted in concrete structure detections. This approach would not damage the structural integrity, and could fulfill most of the detecting requirements of various concrete structures. However, for mass concrete and complicated concrete structural elements, there are still ma...
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Evaluation on the Strength Recovery Rate of Concrete Using Surface Coating Agent
Hyeok Jung Kim,
Nam Wook Kim
Issue:
Volume 9, Issue 1, January 2021
Pages:
18-24
Received:
13 January 2021
Accepted:
20 January 2021
Published:
26 March 2021
Abstract: Cracks and voids of concrete cause the loss of durability. When the cracks reach to the surface of reinforced concrete structures, they can repair by various methods, but there are no effective repairing methods for latent faults or micro-cracks caused by load repetition because they cannot detect by surface state. In this study, we examined the presence or absence of self-repair performance of concrete mixed with the admixture using the coating material for repair, which has been used for a long time. Thus, the basic characteristics of concrete mixed with admixture were identified and self-repair performance was confirmed through experiments. As a result of considering the recovery of the strength of damaged concrete, concrete mixed with a surface coating agent showed a greater recovery effect than concrete mixed with non-mixed concrete. This effect is greater with the age of the damaged material. This shows that even if the repair coating material is mixed as an admixture, the crystal proliferation effect is maintained, and it is confirmed that the concrete mixed with the admixture has self-repairing performance.
Abstract: Cracks and voids of concrete cause the loss of durability. When the cracks reach to the surface of reinforced concrete structures, they can repair by various methods, but there are no effective repairing methods for latent faults or micro-cracks caused by load repetition because they cannot detect by surface state. In this study, we examined the pr...
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The Analysis of Crossed Foundation Beams Lying on the Soil Base
Teimuraz Kikava,
Levan Dolidze
Issue:
Volume 9, Issue 1, January 2021
Pages:
25-30
Received:
20 January 2021
Accepted:
14 February 2021
Published:
26 March 2021
Abstract: To ensure uniform settlement of buildings and structures erected on a weak and heterogeneous soils, reinforced concrete foundations are designed from cross beams, or solid slabs. Currently, cross foundation beams and solid slabs are widely used in construction, like in the construction of high-rise buildings and many other engineering structures. In cross beams, at their intersection with an increase in load and stiffness, especially with an asymmetric load, in addition to bending moments and shear forces, the torques reaching large values can also occur, which are often not taken into account. The torques arisen at the knots of the crossed foundations may, in some cases, have a significant effect on their operation, for example, if the torques reach important values, then additional reinforcement must be placed in the foundations by stipulating the pressures arisen from them. For the correct selection of reinforcement, it is necessary to know the values of not only the bending moments, but also the torques arisen in the constructions. The existing methods of calculation often consider and calculate the crossed foundations as the constructions lying on a linearly deformable base. Besides most of them do not take into account the influence of torques. The methods of calculating the crossed foundations have been worked out by the author, by stipulating effect of bending moments on their working. There are given the formulas to calculate the bending moments, the system of equations is drawn up for linear and angular movements to define the unknown forces arisen at the knots of crossing the foundation beams. After determining these unknown forces, each beam is considered and calculated as a separate one, lying on a linearly deformable foundation.
Abstract: To ensure uniform settlement of buildings and structures erected on a weak and heterogeneous soils, reinforced concrete foundations are designed from cross beams, or solid slabs. Currently, cross foundation beams and solid slabs are widely used in construction, like in the construction of high-rise buildings and many other engineering structures. I...
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