Elastic Scattering of Pions From the Three-nucleon System

We examine the scattering of charged pions from the trinucleon system at a pion energy of 180 MeV. The motivation for this study is the structure seen in the experimental angular distribution of back-angle scattering for pi+ 3He and pi- 3H but for neither pi- 3He nor pi+ 3H. We consider the addition of a double spin flip term to an optical model treatment and find that, though the contribution of this term is non-negligible at large angles for pi+ 3He and pi- 3H, it does not reproduce the structure seen in the experiment.Comment: 15 pages + 5 figure

Seismic Design Studies of Low-Rise Steel Frames

In this investigation, the inelastic behavior of low-rise buildings with steel moment-resisting frames providing the lateral resistance for strong ground motions was examined. The inelastic behavior of frames is dependent on several parameters such as design base shear, beam-to-column strength ratio, moment-resisting connection behavior, nonstructural element participation, etc. The influence of these parameters was determined by performing inelastic time-history analyses. The direct design procedure adopted in the 1988 edition of the Uniform Building Code was used in the seismic design of the frames. Provisions regarding the required lateral stiffness of the frame and strength and ductility of the members were used to proportion the columns, beams and panel zones of each lateral force-resisting frame design. The inelastic behavior (maximum story drifts and shears, ductilities, energy dissipation) computed in the time-history analysis of each frame model was compared to the expected behavior characterized by the code. The investigation concludes with observations about the inelastic behavior of the frames with regard to the numerical modelling of the assumed load-deformation behavior. In addition, the structural performance of frames designed with the direct design procedure contained in the 1988 edition of the Uniform Building Code was evaluated.National Science Foundation Grant DFR 84-1919