Zhong Qing Cheng

Calculations of the Elastic Modulus and Internal Stresses of Orthogonal Symmetric Laminated Plates

The calculations of the elastic modulus and the internal stresses of the orthogonal symmetric laminated plates are very difficult, so experimental or numerical simulation methods were used generally. This paper proposed an Equivalent Strain Model, which can greatly simplify the derivation process of the analytical formulas. By the Equivalent Strain Model, the elastic modulus formula of two-layer plate was derived, and the formula shows that the elastic modulus of the laminated plate meets to the mixture rule of the cross-sectional area ratio of each its single-layer plate; Other formulas derived show that the stress within each single-layer plate is proportional to its elastic modulus and the external load stress, and is inversely proportional to the elastic modulus of the laminated plate. The formula of the average shear stress between two single-layer plates also was derived. Recursive method can be used for multilayer plate calculations.

Study of Effective Thermal Conductivity of Glazed Hollow Bead Concrete

Based on analyzing the mechanism of thermal conductivity of glazed hollow bead concrete, this paper divides the channels of thermal conductivity in concrete, constructs the model of thermal conductivity coefficient based on the Theory of Minimum Thermal Resistance, and confirms the model by using the data of other related literatures and the data of our own experiment. The consequence indicates that this model can calculate the thermal conductivity coefficient under arid state exactly. In order to improve the accuracy of this model, we should take the shape of framework, the interface thermal resistance between concrete and framework into consideration

Relations of Lift and Drag Coefficients of Flow around Flat Plate

In this paper, when Reynolds number is within the range of 10000 to 1000000, the horizontal component of the total pressure of flow around flat plate at high angle of attack was regarded as lift of high angle of attack, and the vertical component was regarded as drag of high angle of attack. The horizontal component of total pressure at small angle of attack was regarded as shape drag, and the total drag coefficient at small angle of attack was considered to the sum of the shape drag and frictional drag at zero angle of attack. For the two states of large and small angle of attack, the application scopes of the formulas of lift and drag coefficients were given. Final, the relations of lift and drag coefficients were obtained by eliminating all angles of attack. Research results show that lift - drag curve of small angles of attack is parabola, and the lift - drag curve of high angles of attack is circle.

Reliability of Gravity Foundation in Coral Sands Subject to Dynamic Wind Load

Taking circular gravity foundation of high-rise structure in coral sands as research object, on the basis of mechanical analysis of foundation during inclination, the inclination vibration equation was established. The amplitude of foundation inclination was calculated. The inclination performance function of foundation was established. JC method is used to calculate the reliability index of foundation. Calculation shows that the amplitude of wind velocity has great influence on the reliability index of foundation when the frequency of sinusoidal wind pressure equals the natural frequency of foundation in inclination vibration. In the design of foundation, the natural frequency of foundation in inclination vibration should be made as far away from the frequency of fluctuating wind pressure as possible.

Calculation of Internal Stresses of Continuous Fiber Reinforced Composite Materials in Longitudinal Loads

Solving the internal stresses of continuous fiber reinforced composite materials is a complex problem, which was studied usally by experimental or numerical calculation method. This paper proposed the equal strain method with virtual external force compensation instead of considering the shear stress in the calculation of the stress in the fiber and matrix of composite materials. By the equal strain method, the formula of longitudinal elastic modulus of continuous fiber reinforced composite materials is derived. The same result was given by other literatures with other methods, which indirectly proved correctness of the equal strain method. Further the internal stress calculation formulaes of the fiber and matrix are derived. The formulaes show that the internal stress of fiber (or matrix) is proportional to the external load and the elastic modulus of the fiber (or matrix), and is inversely proportional to the elastic modulus of the composite material.

Variation of Wind Resistance Reliability of Foundation in Coral Sands

Considering variation of bearing capacity of foundation caused by crushing of coral sands, the variation of wind resistance reliability of foundation in coral sands was studied. Based on the use of exponential decay model of bearing capacity of foundation, the reliability index of foundation at different time was calculated. Calculation shows that in the mid-term of foundations life in coral sands, attention should be paid to the assessment of wind resistance reliability of foundation, and it is necessary to track the variation of wind resistance performance of foundation in time. After a long time of operation, assessment must be applied to the wind resistance reliability of foundation combining with inspection.

Calculation of Settlement and Inclination of Gravity Foundation in Coral Sands Based on Transfer Matrix Method

Settlement and inclination of gravity foundation are calculated and analyzed using transfer matrix method. The influences of vertical load, overturning moment, foundation width b and deformation modulus of subgrade soil E on the settlement and inclination of foundation are analyzed. Calculation shows that increasing both the width of foundation b and deformation modulus of subgrade soil E can improve the anti-overturning performance of foundation, and reducing the foundation width and increasing the deformation modulus of subgrade soil can reduce the subgrade settlement. This method can effectively calculate the settlement and inclination of gravity foundation.

Reliability Analysis of Subgrade Bearing Capacity of Gravity Foundation of Wind Turbine Based on JC Method

The design of foundation of wind turbine should meet the requirement of subgrade bearing capacity. In this paper, reliability method was used to analyze the bearing capacity of gravity foundation of wind turbine. The circular gravity foundation in coral sands is taken as research object. By deriving the expression of maximum pressure at the edge of foundation base under the action of overturning moment, the performance function of subgrade bearing capacity reliability analysis is established. JC method is used to calculate the subgrade bearing capacity reliability index. Effect of foundation size to reliability index is analyzed. Iterative calculation shows that the method proposed in this paper can calculate the reliability index of foundation quickly.