Research on Wind Load Calculation Based on Identical Guarantee Rate Method

Wind load on building surface is one of the main loads for structural design; scholars in this field have put forward some methods to calculate wind load, such as Simiu method and Kasperski method. Based on the basic theory of probability and the systematic analysis of the surrounding environment and turbulence, a random variable model for calculating wind load is established. According to the model, through the analysis of the relationship between guarantee rate and wind load, a numerical calculation method to calculate wind load is proposed based on extreme value analysis and polynomial fitting theory. To verify the performance of the algorithm, wind tunnel experiments were carried out to obtain a large number of first-hand measured data of high-rise building (Shanghai World Financial Center). Based on the measured data, the algorithm is simulated, and calculated results are analyzed, including wind pressure distribution on building and probability distribution of fluctuating wind pressure of some measuring points. The validity and accuracy of the proposed model and algorithm are verified by the comparative analysis and theoretical analysis of the calculation results.

Spatial-Temporal Change Analysis for Multivariate Drought Risk Based on Bayesian Copula: Application to the Balkhash Lake Basin

In this study, a spatial-temporal Bayesian copula (SBC) method is developed through integrating spatial-temporal analysis and Bayesian copula into a general framework. SBC method can help model dependence structures of variable pairs and handle the uncertainty caused by parameter in copulas, and SBC can reveal the spatial and temporal changes of drought events. SBC is applied to the Balkhash Lake Basin (in Central Asia) to analyze spatial-temporal characteristic and drought risk in 1901-2020. Several findings can be summarized: (1) Balkhash Lake Basin suffered 53 drought events in 1901-2020, and five typical severe drought events occurred in 1916-1920, 1943-1945, 1973-1977, 1995-1998 and 2007-2009; (2) the most severe drought event lasted for 40 months (1973.10-1977.1), affecting 335,800 km2 of the study basin; (3) drought usually develops from east to west, and Ili River delta and alluvial plain has the highest frequency of drought (47.2%), following by plateau desert (28.3%) and arid grassland in north Balkhash Lake (24.5%); (4) drought shows significant seasonality in the study basin, which usually begins in spring and summer (64.2%) and ends in summer and autumn (66.0%); and drought risk of middle and lower reaches of Ili River is highest in spring and summer; (5) in Balkhash Lake Basin, multivariate characteristics (duration, severity and affected area) significantly affect drought risk; (6) the range of drought risk is [1.9%, 18.1%], [3.7%, 33.1%], [8.7%, 46.0%], [16.0%, 55.1%] and [27.6%, 59.8%] when guarantee rate is 0.99, 0.98, 0.95, 0.90 and 0.80, respectively.

Further Analysis of Non-Gaussian Wind Pressure Peak Factor Calculation

The wind pressure time history of high-rise building cladding is mostly non-Gaussian distribution, and there is a one-to-one correspondence between a specified guarantee rate and its corresponding peak factor. A stepwise search method for calculating the peak factor of non-Gaussian wind pressure and a gradual independent segmentation method for extracting independent peak values have been proposed to determine the relationship accurately in the previous study. Based on the given experiment and calculation results in the existing research results, more analysis can be given to enrich the study on this topic. In this paper, some characteristics of wind pressure coefficient time series in time and frequency domain are analysed. Based on the basic theory of fractal, the R/S analysis of wind pressure time series is made, and the fractal characteristics of wind pressure coefficient time series are explained. Based on the statistical theory, the relationship characteristics between high-order statistics and peak factors are studied. The correlation between the guarantee rate and the corresponding peak factor is analysed, and the guarantee rates calculated by the Davenport peak factor method are evaluated. The power spectrum characteristics of fluctuating wind pressure are analysed and the relationship between turbulence characteristic frequency and optimal observation time interval is discussed.

Copula-Based Method for Estimating the Minimum Void Ratio Parameters of Tailings Deposits

The pore ratio is an important parameter affecting the stability and safety of tailings reservoirs; however, the relationship between the pore ratio and physical properties of tailings sand has not been researched in-depth. In this paper, using the tailings from a tungsten mine in southern Shaanxi as a case study, the correlation between the minimum void ratio and related parameters is analyzed, based on laboratory test data, and the optimal marginal distribution function of the parameters is determined. The Gumbel-Hougard copula function that best describes the correlation between parameters is identified, and it is used to establish the joint probability distribution model of the three parameters, and the guarantee rate α is introduced to estimate and analyze the minimum void ratio. The results show that the optimal edge distribution of the fine particle content and specific gravity follows a truncated normal distribution, and the optimal edge distribution of the minimum void ratio follows a logarithmic normal distribution. According to AIC criterion, the Gumbel-Hougard copula is the best three-dimensional copula function to fit the minimum void ratio and related parameters. When the guarantee rate α is 0.485, the joint probability distribution model achieves optimal performance in terms of estimating the minimum void ratio. The maximum error of the estimation is 1.99%, which is verified through data, and the estimation meets the requirements for practical engineering. The method proposed in this paper uses the existing measured data to establish a joint probability distribution model and combines the collected fine particle content and specific gravity data with the guarantee rate to estimate the minimum void ratio, providing a novel basis for the study of the physical properties of tailings.

A Bayesian copula-based spatio-temporal method for multivariate drought risk analysis: A case study of the Balkhash Lake Basin

In this study, a Bayesian copula spatio-temporal drought risk analysis (BCSDA) method is developed through coupling Bayesian copula and spatio-temporal analysis into a general framework. BCSDA can effectively identify drought characteristics and reveal the temporal and spatial variation, as well as analyze drought risk at different guaranteed rates based on the influence of multivariate interaction. Then, BCSDA is applied to the Balkhash Lake Basin (a typical arid watershed in Central Asia) for analyzing drought risk during 1901-2017. Major findings are: (i) Balkhash Lake Basin suffered 53 drought events in 1901-2017, and the most severe drought event occurred in October 1973 to January 1977, which lasted for 40 months and developed into an extreme drought during April 1975 to June 1976, affecting 335,800 square kilometers of the study basin; (ii) most of the drought events developed in the direction of east-west, and Lli River delta and the alluvial plain were the most severe of drought (47.2%), followed by the plateau desert area (28.3%) and the arid grassland in north of Balkhash Lake (24.5%); (iii) drought shows significant seasonality which usually began in spring and summer (64.2%) and ended in summer and autumn (66.0%); (iv) in Balkhash Lake Basin, multivariate characteristics (duration, severity and area) would significantly affect drought risk; (v) the range of drought risk would be [1.9%, 18.1%], [3.7%, 33.1%], [8.7%, 46.0%], [16.0%, 55.1%] and [27.6%, 59.8%] when guarantee rate is 0.99, 0.98, 0.95, 0.90 and 0.80.

Research on Scale Demonstration Technology of Inter Basin Water Transfer Project in Agricultural Irrigation

Inter-basin water transfer projects are powerful measures for resolving the uneven distribution of water resources, but their scale directly affects the associated investment and income. Therefore, determining the scale of an inter-basin water transfer project is essential. Based on the inter-basin agricultural water transfer project in the Sanjiang Plain, Northeast China, combined with the suitable development scale of the irrigation area with the joint allocation of existing water sources, this research proposes a technique to demonstrate the scale of an inter-basin water transfer project based on dynamic trial feedback under the condition of the optimization method of despiking of the groundwater allocation; the water transfer project scale is demonstrated for each section in reverse order. According to the water demand prediction results in the study area, the scale of water transfer project BC is demonstrated, and the scale of water transfer project AB is demonstrated on the basis of the BC scale. The final AB and BC water transfer scales decrease by 15% and 13%, respectively, compared with the conventional method under the premise that the water supply guarantee rate is 75%. When the water is transferred, the process is stable, and the utilization rate of the canal is high, thereby saving investment funds and facilitating project scheduling and management.

Reliability analysis of solar energy and biogas boiler combination warming system

In order to solve the problem of low biogas production caused by low temperature in northern cold area, the solar energy and biogas boiler combination warming system is proposed to raise the temperature of biogas digester. In this paper, under the condition of the optimum area of solar collector, it's obtained that changeable rule of solar energy guarantee rate with month and rule of heating ratio of biogas boiler in the whole year. The solar energy guarantee rate of the system is more than 55.9%, and the combined heating capacity of solar energy and biogas boiler is enough to meet the requirements of annual operation conditions, which is reliable in the northern cold area.

Method for Inferring the Design Value of the Resistance Based on Probabilistic Model

Methods for inferring the design value of the resistance based on test have long been studied extensively, but the existing methods have several limitations on unified guarantee rate ensurance and reliability control. Firstly, the rationales and deficiencies of the present methods in ISO 2394 : 2015 and EN 1990 : 2002 were generalized. Secondly, in view of the disadvantages, a new inferring method combining the probability model of resistance with statistical approach was put forward. The proposed method established a relationship among design resistance, probability characteristics of known factors, and statistical results of unknown factors and possessed a rigorous and sound theoretical basis on both conditions that the coefficient of variation of model uncertainty was unknown and full known. Lastly, a contrast work was carried out between the Eurocode method and the proposed method; the results showed that the latter method had a higher inferring value, which means a better inferring result.