ZESZYTY NAUKOWE POLITECHNIKI GDA Ń SKIEJ Nr 522 Budownictwo Lądowe LI 1995 IRENEUSZ KREJA Katedra Mechaniki Budowli RÜDIGER SCHMIDT Bergische Universität, Germany MODERATE ROTATION SHELL THEORY IN FEM APPLICATION Two variants of the first-order shear deformation moderate rotation theory (MRT) of anisotropic shells have been considered in the present paper. A different interpretation of the assumption of the inextensible director has been applied in each variant. Both variants have been implemented in a numerical algorithm based on the finite element method (FEM). A practical realisation of the proposed algorithm finds a form of the computer program SHEL7, where the family of the 9-node Lagrangian elements is supplemented with the 9-ANS element based on the assumed interpolation of strains. The behaviour of the proposed algorithm is tested in several illustrative numerical examples 1. INTRODUCTION In the last decade the Finite Element Method analysis of shell structures is one of the areas with the most intensive research activity in the whole computational mechanics. Studying most of the recently published proceedings and review papers in this subject (see e.g. [1, 2, 3]) one can find a relatively small number of publications dealing with the geometrically nonlinear FE analysis of anisotropic shells. One stream of an activity in this group is connected with the first-order shear deformation moderate rotation theory (MRT) of anisotropic shells proposed by Schmidt and Reddy in [4]. The first numerical results based on this variant of the moderate rotation theory (MRT) of shells were published by Palmerio, Reddy and Schmidt in [5]. More detailed studies of the finite element aspects of MRT were presented in the recent