NON-UNIFORM STIFFNESS BEAM-COLUMN THEORY AND ITS APPLICATION

In order to solve the problems of non-uniform cross-section in the practice of deviation control, typtical mechanical models of non-uniform stiffness are discussed in this paper.Based on the differential equations of deflection curve and conditions of continuity and boundary of non-uniform stiffness beam-column, the analytical calculation formulae for deflection and end slope angles of beam-column are derived.Furthermore, appling beam-column theory principle of superposition,the mechanical problems of bottom hole assembly(BHA) with downhole control tool acted by a transverse concentrated force and BHA with variable gauge stabilizer can be solved.Non-uniform stiffness beam-column theory has been successfully used in the mechanical analysis of BHA and it provides theory foundations for downhole control tool design,BHA optimization and deviation control operation.