Analysis Carrying Capacity of Hydraulic Concrete Dam

2014 ◽  
Vol 716-717 ◽  
pp. 400-405
Author(s):  
Chang Ming Cheng
Keyword(s):  
Volume Ratio ◽  
Arch Dam ◽  
Hydraulic Pressure ◽  
Damage Evaluation ◽  
Geological Process ◽  
Concrete Dam ◽  
Hydraulic Concrete ◽  
Local Earthquake ◽  
The Relationship ◽  
Body Damage

This paper makes analysis on accelerated speed overload and hydraulic pressure after earthquake, as well as the relationship between the ground motion peak acceleration and the dam body displacement, dam body damage volume ratio, and dam facing damage volume ratio. According to dam body partition, this paper takes the ratio of over stress accumulative duration and stress required capacity as parameters, and studies arch local earthquake damage evaluation of dam body partition. After analysis, it is found that after arch dam experiences different geological process, there are damages in both sides of dam abutment and upper part of dam body, overstressed area expands continuously and local damages take place.

Comparison of the tussive effects of histamine and methacholine in humans

1983 ◽  
Vol 55 (2) ◽  
pp. 541-546 ◽  
Author(s):  
A. M. Chausow ◽  
A. S. Banner
Keyword(s):  
Chronic Cough ◽  
Volume Ratio ◽  
Forced Expiratory Volume ◽  
Additional Mechanism ◽  
Cough Response ◽  
Inhalation Challenge ◽  
The Relationship ◽  
Linear Correlations

The tussive and bronchoconstrictive effects of histamine inhalation in 7 normals, 7 asthmatics, and 24 patients with chronic cough (PCC) were measured by counting coughs during a standard histamine inhalation challenge. All PCC had a tussive response. Fifteen PCC exhibited significant linear correlations between cough count and either the change in forced expiratory volume at 1.0 (delta FEV1) or conductance-volume ratio (sGaw) (delta sGaw). Normals and asthmatics had little or no cough. Metaproterenol pretreatment in seven PCC reduced both the FEV1 and cough response to histamine without changing the relationship between cough and delta FEV1. The tussive and bronchoconstrictive effects of methacholine inhalation were also measured in 7 asthmatics and 16 PCC. One asthmatic coughed. Fifteen PCC coughed. There were significant linear correlations between cough count and delta FEV1 or delta sGaw in 10 PCC. At comparable delta FEV1 and delta sGaw, histamine produced more cough than methacholine. These data indicate that during inhalation of histamine or methacholine by PCC cough is related to, and may be caused by, bronchoconstriction. Histamine also causes cough by an additional mechanism not related to bronchoconstriction.

The Diagnostic Method of Concrete Dam Monitoring Information Valid Interval

2012 ◽  
Vol 226-228 ◽  
pp. 2072-2077
Author(s):  
Dong Qin ◽  
Xue Qin Zheng ◽  
Fa Meng Wang ◽  
He Zhi Liu
Keyword(s):  
Influential Factors ◽  
Arch Dam ◽  
Dynamical Structure ◽  
Concrete Dam ◽  
Concrete Arch Dam ◽  
Structural Mutation ◽  
Mutation Theory ◽  
Dam Monitoring ◽  
Mutation Sequence ◽  
Monitoring Information

On the basis of the analysis of the displacement of concrete dam and its related influential factors, based on the evolvement of nonlinear dynamics of concrete dam, it can effectively identify the mutations position of measured value and the attribute interval of dynamical system applied with the wavelet analysis, dynamic structural mutation theory and other numerical analysis methods. When detecting after separating structural mutation sequence, it can finally get the relative stable displacement time series of dynamical structure, so it can realize the diagnostic separation of the monitoring information effective interval. At the end of the paper, through applying a certain concrete arch dam, it is proved that the proposed method of concrete dam mutations diagnosis of is of great significance for the real-time monitoring of the workability state of a dam.

scholarly journals Crack-Considered Elastic Net Monitoring Model of Concrete Dam Displacement

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Jiingmei Zhang ◽  
Chongshi Gu
Keyword(s):  
Water Pressure ◽  
Elastic Net ◽  
Arch Dam ◽  
Time Dependent ◽  
Concrete Dams ◽  
Displacement Monitoring ◽  
Concrete Dam ◽  
Monitoring Model ◽  
Proposed Model ◽  
Dependent Component

Displacement monitoring data modeling is important for evaluating the performance and health conditions of concrete dams. Conventional displacement monitoring models of concrete dams decompose the total displacement into the water pressure component, temperature component, and time-dependent component. And the crack-induced displacement is generally incorporated into the time-dependent component, thus weakening the interpretability of the model. In the practical engineering modeling, some significant explaining variables are selected while the others are eliminated by applying commonly used regression methods which occasionally show instability. This paper proposes a crack-considered elastic net monitoring model of concrete dam displacement to improve the interpretability and stability. In this model, the mathematical expression of the crack-induced displacement component is derived through the analysis of large surface crack’s effect on the concrete dam displacement to improve the interpretability of the model. Moreover, the elastic net method with better stability is used to solve the crack-considered displacement monitoring model. Sequentially, the proposed model is applied to analyze the radial displacement of a gravity arch dam. The results demonstrate that the proposed model contributes to more reasonable explaining variables’ selection and better coefficients’ estimation and also indicate better interpretability and higher predictive precision.

Modal Velocity-Based Multiaxial Fatigue Damage Evaluation Using Simplified Finite Element Models

2020 ◽  
Vol 87 (11) ◽  
Author(s):  
Kurthan Kersch ◽  
Elmar Woschke
Keyword(s):  
Finite Element ◽  
Fatigue Damage ◽  
Cross Section ◽  
Multiaxial Fatigue ◽  
Finite Element Models ◽  
Damage Evaluation ◽  
Geometric Factors ◽  
The Relationship ◽  
General Method

Abstract This work proposes a new method for the fatigue damage evaluation of vibrational loads, based on preceding investigations on the relationship between stresses and modal velocities. As a first step, the influence of the geometry on the particular relationship is studied. Therefore, an analytic expression for Euler Bernoulli beams with a non-constant cross section is derived. Afterward, a general method for obtaining geometric factors from finite element (FE) models is proposed. In order to ensure a fast fatigue damage evaluation, strongly simplified FE-models are used for the determination of both factors and measurement locations. The entire method is demonstrated on three mechanical structures and indicates a better compromise between effort and accuracy than existing methods. For all examples, the usage of velocities and geometric factors obtained from simplified FE models enables a sufficient fatigue damage calculation.

scholarly journals Investigation of Stochastic Seismic Response and Index Correlation of an Arch Dam Using Endurance Time Analysis Method

2020 ◽  
Vol 2020 ◽  
pp. 1-23
Author(s):  
Qiang Xu ◽  
Shutong Xu ◽  
Jianyun Chen ◽  
Jing Li
Keyword(s):  
Seismic Response ◽  
Failure Modes ◽  
Response Spectrum ◽  
Volume Ratio ◽  
Arch Dam ◽  
Dynamic Responses ◽  
Rock Foundation ◽  
Time Analysis ◽  
Endurance Time ◽  
Joint Opening

The seismic dynamic response and correlation between various indicators of an arch dam under a series of stochastic earthquake excitation are analysed. Seismic response assessment of a concrete arch dam is conducted through nonlinear endurance time analysis (ETA) of a typical arch dam. The 289 m high Baihetan arch dam in Southwest China (as a case study) is subjected to a set of 10 three-component endurance time acceleration histories (ETAHs) synthesised on the basis of the design site acceleration response spectrum to increasing peak ground acceleration (PGA). The effects of dam-reservoir-foundation interaction, radiation damping of infinite rock foundation, and nonlinearities of dam material and joint contact elements are considered. The indices to failure modes of damage propagation through the dam body and the deformation and joint opening beyond the limit states of the arch dam are identified. Dynamic responses, including deformation, joint opening, and damage distribution, are statistically analysed. The dispersion and correlation of indicators are analysed by employing the coefficient of variation and coefficient of correlation, respectively. The deterministic relationships between contraction joint opening, displacement, and damage volume ratio are obtained by using a multivariate fitting method. The results show that those failure indices have similar exponential trends, and seismic intensity parameters exert a significant influence on seismic response and damage under increasing PGA. The results of correlation and fragility analysis demonstrate that damage volume ratio and the sum of joint opening are consistent, which can provide a strong scientific basis for predicting earthquake damage.

scholarly journals Investigation of Non-fully Similar Laws of Damage to an Arch Dam in Shaking Table Model Tests

2020 ◽  
Vol 12 (11) ◽  
pp. 168781402097449
Author(s):  
Qiang Xu ◽  
Jianyun Chen ◽  
Bo Liu ◽  
Jing Li
Keyword(s):  
Crack Propagation ◽  
Shaking Table Test ◽  
Arch Dam ◽  
Shaking Table ◽  
Scale Model ◽  
Similar Relationship ◽  
Prototype Structure ◽  
The Relationship ◽  
Elastic Stage ◽  
Propagation Stage

In order to overcome the defect that the general shaking table test can’t clarify the scale relationship between the prototype structure and the scale model in the damaged area based on the fully similar laws, we derived a method that can analyze the relationship between the prototype structure and the scale model in the damaged area based on non-fully similar lows and verified it. We selected the appropriate material (the emulation concrete material, ECM), which has a good scale relationship with the prototype material in the elastic stage, the crack appearance stage, and crack propagation stage (damage stage). We proposed some similar ratios to reveal the similar relationship between the prototype structure and the scale model in the elastic stage, the crack appearance stage, and the crack propagation stage. Especially, we proposed two similar ratios: cr and hr (deduced by the fracture toughness similarity requirements and the fracture energy similarity requirements, respectively) which can well reflect the similar relationship between the prototype structure and the scale model in the damaged area. In order to verify these ratios, we compared the results of the prototype structure numerical simulation with those of the shaking table test of the scale model. The results show that hr has higher accuracy for predicting the relationship between the prototype structure and the scale model in the damaged area.

A re-examination of the relationship between lattice strain, octahedral tilt angle and octahedral strain in rhombohedral perovskites

1996 ◽  
Vol 52 (6) ◽  
pp. 954-960 ◽  
Author(s):  
N. W. Thomas
Keyword(s):  
Tilt Angle ◽  
Lattice Strain ◽  
Numerical Solutions ◽  
Volume Ratio ◽  
Group Symmetry ◽  
Acta Cryst ◽  
Fourth Degree ◽  
Parametric Curves ◽  
Lattice Strains ◽  
The Relationship

A new expression is proposed for the relationship between lattice strain 90°− αpc ( αpc: pseudo-cubic angle) and mean BO6 octahedral tilt angle <ω> in rhombohedral perovskites ABO3. It is derived from volumetric arguments, leading to a cubic equation which incorporates lattice strain 90° −αpc and octahedral elongation explicitly. Numerical solutions of this equation are derived for equally spaced values of octahedral strain, giving rise to a set of parametric curves which relate ω to 90° − αpc for different values of η. These curves can be represented as polynomials of the fourth degree, thereby enabling their routine use in the analysis of rhombohedral perovskite structures. It is anticipated that these parametric curves will supersede earlier work [Megaw & Darlington (1975). Acta Cryst. A31, 161–173], in which an analytical expression was derived linking 90° − αpc, ω and octahedral strain for positive lattice strains only. By comparison, the relationship proposed here accommodates both negative and positive lattice strains. Correlations between values of <ω>, η, 90° − αpc and space-group symmetry are found, with an analysis of known rhombohedral and orthorhombic Pnma structures revealing the importance of cationic charges in determining symmetry. Since the polyhedral volume ratio VA/VB may be quantitatively related to <ω>, allowed values of tilt angle, lattice strain and octahedral elongation may be inferred for a given composition, which has characteristic values of VA and VB .

Temperature Rebound Influenced by Environment Temperature Analysis of the Irrigated Area of a High Arch Concrete Dam under Constrcution

2014 ◽  
Vol 580-583 ◽  
pp. 2045-2049 ◽  
Author(s):  
Xun Hui Chen ◽  
Yao Ying Huang ◽  
Bai Lin Xu ◽  
Dan Dan Liu ◽  
Xiao Bin Wei
Keyword(s):  
Thermal Conductivity ◽  
Arch Dam ◽  
High Arch Dam ◽  
Concrete Dam ◽  
Construction Period ◽  
Average Temperature ◽  
Environment Temperature ◽  
Dam Site ◽  
Heat Preservation ◽  
Annual Average Temperature

For a temperature rebound in the irrigated high arch dam during the construction period, using finite element method to research the influence of environment temperature to temperature rebound of the irrigated high concrete arch dam. Assuming that the initial temperature of the dam concrete is the joint grouting temperature. This paper presents a simulation of the temperature rebound of the high arch dam which is caused by the monthly average environment temperature, and performs sensitivity analysis to research the influence of thermal conductivity and surface heat preservation on the temperature rebound. According to the analysis,when the high arch dam sealing temperature is lower than the dam site annual average temperature, the dam site temperature inevitably would flow backward,slowly,to the irrigation area.The larger the thermal conductivity is,the quicker the temperature rebound speed will be. And benzene board insulation can reduce concrete temperature rebound rate, if the heat preservation benzene board is thicker,the temperature rebound rate is smaller.

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