Showing papers by "Tongji University published in 1982"

Shearing Stress due to Prestress in Variable Depth Beam

Abstract: General formulas to estimate shearing stress in prestressed concrete beams due to prestress force are given. These equations also can be used to calculate dead load and live load moment by substituting the corresponding values of shearing force and moment. Finally, it is demonstrated how tension or compression can be calculated.

The Reflection Seismogram In a Solid Layered Earth

Abstract: Current approaches to seismic data processing and interpretation ignore the change in reflection coefficient with incident angle. The justification is typically based on fluid earth models or models in which the ratio of compressional velocity to shear velocity (C/sub p//C/sub s/) is assumed constant. In clastic basins, normal incidence reflectivity is low, and variations in C/sub p//C/sub s/ can be significant. Under these conditions the change in reflection coefficient with incident angle can be very significant. Replacement of the plane wave normal incidence synthetic seismogram with the point source solid earth synthetic seismogram is likely to lead to important changes in our approach to acquisition, processing, and interpretation of seismic reflection data. In general, in a clastic basin, we might expect to see a different set of rocks emplasized on partial stacks from different offset ranges. The sensitivity of our solid earth synthetic seismogram to changes in Poisson's ratio is such that we suggest that conventional reflection data in clastic basins should permit the extraction of band-limited shear impedance logs as well as compressional impedance logs. Attempts to work only with the CDP stacked data should yield a hybrid impedance log, a mixture of the effects of compressional and shearmore » velocity variations. The expected variation in reflectivity with offset in clastic basins suggests that we should seriously question our conventional processing and interpretation assumptions in these areas. It also suggests that conventional seismic reflection data might yield a shear impedance image and an improved compressional impedance image rather than the currently employed hybrid impedance image.« less

Recent advances in the method of weighted residuals on solid mechanics in China

Abstract: This paper presents a review of research work in recent years on the method of weighted residuals (MWR) on solid mechanics in the People's Republic of China. MWR, as a kind of mathematical method by which approximate solutions of differential equations may be obtained, is being extensively used in the fields of fluid mechanics, heat transfer, etc. In China, prompted by needs, this method has been developed to be used on solid mechanics in recent years and has also been recognized as having merits over other methods.

Automatical meshing technique used in the mixed FEM for stress analysis of reinforced conical branch pipe junctions

Abstract: In this paper the use of the mixed finite element method for stress analysis of reinforced conical branch pipe junctions subjected to internal water pressure is presented, branch pipe junction being considered as an intersection body of two thin conical shells. For the purpose of computing a large number of branch pipe junctions with different geometrical varieties, an automatical meshing routine has been up in the mixed FEM program with 3 geometrical parameters of the junctions to be varied, i.e., the angle included between axes of the main pipe and the branch pipe, the thickness of the wall of the shell and that of the reinforcing pad and the ratio of diameters of the branch pipe to that of the main pipe. The computer program has been provided functions to distinguish 8 kinds of different meshes and 12 sorts of elements, and to lay automatically coordinates of nodes as well as different boundary conditions of element. In this way, stress analyses of 101 junctions have been carried out and results of computations are excellent.