A Mathematical Model for the Identical Slope Curved Surface

in the design of civil and water conservancy projects, the identical slope suffice isfrequently used. Its mathematical model may be formulated as an envelope of a cone when itS vertexmoves along the cylindrical helix. According to the principle of conStrUcting the envelope curves of afamily of circles, the parametric equstion for the identical slope surface is established. The parametricform makes it most convenient to draw the contour lines and grade lines, and is well suited toproduce indexed projection of identical slope surface in civil and water conservancy projects.

Experimental study on the influence of hydrostatic stress on the Lode angle effect of porous rock

To investigate the deformation mechanisms of rock under hydrostatic stress, destructive experiments were conducted on sandstone under different levels of hydrostatic stress and stress Lode angles. The results reveal that the shape of the strength envelope on the π plane gradually changes from the shape of the Lade criterion to the shape of the Drucker-Prage criterion with an increase in hydrostatic stress.Normally, there exists a deviation between the strain and stress paths for porous rocks on the π plane,and the deviation decreases with an increase in stress Lode angle and hydrostatic stress. A rock failure hypothesis based on the rock porous structure was proposed to investigate the reasons for the abovementioned phenomena. It was found that the shear expansion in the minimum principal stress direction is the dominant factor affecting the Lode angle effect(LAE);the magnitude of the hydrostatic stress induces the variation of the porous structure and influences the shear expansion. Therefore, the hydrostatic stress state affects the LAE. The failure hypothesis proposed in this paper can clarify the hydrostatic stress effect, LAE, and the variation of the rock strength envelope shape.

Simulation of Somatotype of Hydraulic Turbine Draft-Tube

Elbow draft-tubes are widely used in large- and medium-sized hydropower stations in many countries. During the application, handling the somatotype of elbow tubes has been found challenging： in order to maintain the designed shape of draft tube and to meet the requirement of construction lofting, the configuration of reinforcing bars and the fabrication of templates, the geometry of elbow tubes has to be accurately calculated to draw engineering graphics. Based on the derived equations in this paper, the motion of elbow tube curve envelope is simulated by using computers, which shows directly the smoothness of the curve and provides dynamic simulation for the study and optimization of the design and construction of elbow draft tubes, along with the front view and bottom view.

Hysteretic Model for Corroded Rectangular Reinforced Concrete Bridge Column Under Seismic Loading

Additional hysteretic experiments for corroded rectangular reinforced concrete(RC)columns with an axial load ratio of 0.27 were implemented.A quasi-static cyclic lateral loading with constant axial force was subjected to tests.Herein,a modified ductility factor model for corroded RC column is developed on the basis of the previous work and additional experiments.The model involves the influence of both the corrosion ratio of longitudinal rebar and the axial load ratio.A four-linear envelope curve model concerning lateral load and displacement is proposed in a combination of determination rules of the peak point and the failure strength point.The hysteretic model of corroded RC columns is developed by considering both degraded unloading stiffness and reloading stiffness on the history peak point.The hysteretic model can predict the residual life of corroded RC columns under seismic loading.