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Abstract: In this paper, the inverse step transformation, an important transformation relation in structural matrix analysis, is briefly reviewed, and several application examples are discussed and analyzed. Finally, the stiffness analysis formula of a transition element-pier element derived from the inverse step transformation is introduced in solving practical structural calculation problems.

Abstract: Let E be the set of measurable points in n-dimensional space, i.e. 0≤mE≤+∞.In this paper, several properties involving integrals in Lebesgue integrals are studied (the sum of integrable functions on E is also an integrable function on E, and the integral of sum is equal to the sum of integrals;An integrable function on E multiplied by a constant is also an integrable function on E, and the constant can be mentioned outside the integral sign, etc.).

Abstract: In order to solve the design and production problems involving gas-liquid two-phase flow, it is necessary to determine the flow pattern of two-phase flow under certain operating conditions.The hydrodynamics, heat and mass transfer of two-phase flow are different with different flow patterns.However, there has been no systematic review on the study of two-phase flow patterns.In this paper, the foreign research on gas-liquid two-phase upflow pattern in vertical tubes since 1950s is evaluated, the existing problems are pointed out, and some basic viewpoints and further research directions are put forward.

Abstract: Steel-concrete composite structure is a new type of structure after steel and concrete structure.The basic meaning of composite structure is: in a member, the steel and concrete structural materials are closely combined into a whole, and jointly bear the load.The advantage of this type of structure is that in large, high-rise and heavy building structures, it has better applicability than the reinforced concrete structure alone - reducing the volume of components, increasing the use of space and reducing the foundation load, saving wood forms and supports, saving the amount of concrete, having better seismic performance and eliminating the embedded parts in the components.Compared with the steel structure alone, the steel material is greatly saved.In this paper, the steel-concrete composite structure is divided into two parts, column and beam, and the structure, mechanical performance, advantages and disadvantages, application range and domestic and foreign development of the composite column and beam are reviewed respectively.

Abstract: The experimental results of 40 deep beam members are given in this paper.The working performance, failure mode and strength calculation of deep beam under symmetric concentrated load are studied.The effects of shear span ratio, concrete strength, loading plate size, ratio of abdominal reinforcement and ratio of longitudinal reinforcement on the shear strength of deep beams are discussed.The formula for calculating the shear strength is derived from the tensile model of the draw-bar arch, and is in good agreement with the experimental results of about 194 deep beams at home and abroad.The problems of bending strength of inclined section and cracking strength of deep beam are also discussed, and the calculation formulas are given.

Abstract: In this paper, according to the stress characteristics of the rectangular short column of reinforced concrete under eccentric compression, the internal force variation law of concrete and steel bar on the normal section is analyzed, and three parameters representing the internal force characteristics of section are introduced.With reference to some test data of the bias group in China, the function expression of the parameters is determined, the strength calculation formula of the short column is established, and a simplified calculation method is proposed for reference.

Abstract: This paper briefly introduces the main achievements of our research on five-link floating body brake in the past ten years.Firstly, the motion characteristics of the gate are analyzed from the analysis of the working state, and the calculation formulas of lift, fall and balance of the five-link floating body gate are established.Then the model test is discussed and the dynamic similarity model law is proposed.Based on a large number of experimental data, a practical diagram of the moment of overflow water pressure is obtained, which can be used by designers in calculation.Finally, several important problems of the floating body gate are briefly discussed, namely, starting problem, self-locking and self-floating problem, non-synchronization and fast descent and loss of control problem which are closely related to them.

Abstract: The stress distribution and stress concentration on the sluice pier of a spillway dam are analyzed by using three-dimensional photoelastic freezing stress and slice method.The epoxy resin model used in the study was precision-cast from a cement mold shell with a silicone rubber lining.This form can be used multiple times.The shear force difference method is used to calculate the stress and separate the principal stress, and the stress distribution, the principal stress trace line and the maximum principal stress contour line of some sections on the pier under the action of symmetric load and asymmetric load are determined.The research results can be used for engineers and technicians to design the pier.

Abstract: In this paper, we discuss the condition that the transition quantity i or Mc after RL or RC series circuit is connected to sinusoidal voltage source under zero initial conditions, and apply the duality principle to extend the conclusion to the duality problem that gc or gL parallel circuit is connected to sinusoidal current source under zero initial conditions.

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