Lý thuyết bậc I: tính toán các lực trên một hệ chịu lực không biến dạng. Điều này có nghĩa là các biến đổi hình học của hệ chịu lực do tải trọng tác động bị bỏ qua. Việc này chỉ được chấp nhận khi biến dạng nhỏ không làm ảnh hưởng đến kết quả tính toán. | Design for axial load 800kN and moment 50 Assume that dc 300 mm and A. 905 mm2 two T24 bars . Since dc is between t 2 and t-d2 fs2 can be determined from _ f - d2 - _ 460 -130 - 300 s2 t-2d2 J 460-260 y Take fs1 . Then Nd - mm Ỉ ms 13 X 460 X 300 460 X 905 X - X103 xio3 780 192 972 which is adequate M bdc t-dc Ị 44 d V I mm Í ms X 13 X 460 X 300 X 160 460 X 905 X 100 X X106 xio6 kN m which is adequate. REINFORCED MASONRY COLUMNS USING ENV 1996-1-1 Introduction The Eurocode does not refer separately to specific design procedures for reinforced masonry columns although in section of the code reference is made to reinforced masonry members subjected to bending and or axial load. In the section a diagram showing a range of strain distributions in the ultimate state for all the possible load combinations is given and these are based on three limiting strain conditions for the materials. 1. The tensile strain of the reinforcement is limited to . 2. The compressive strain in the masonry due to bending is limited to . 2004 Taylor Francis 3. The compressive strain in the masonry due to pure compression is limited to . Using these conditions a number of strain profiles can be drawn. For example if it is decided that at the ultimate state the strain in the reinforcement has reached its limiting value then the range of strain diagrams take the form shown in Fig. . In Fig. the strain diagrams all pivot about the point A the ultimate strain in the reinforcement. Line 2 would represent the strain distribution if the ultimate compressive strain was attained in the masonry at the same time as the ultimate strain was reached in the reinforcement and line 1 an intermediate stage. In the Eurocode additional strain lines such as line 3 are included in the diagram but since no tension is allowed in the masonry these strain distributions
