Redistribution Calculation

The TBDY2018 code permits redistribution in masonry buildings under certain conditions.

TBDY2018 Article " 11.3.6 – Redistribution on each load-bearing wall shall be permitted, provided that the shear force on the wall is not reduced by more than 25% and not increased by more than 33%."

Redistribution can be used in new design analyses and in the performance analysis/strengthening of existing structures.

Redistribution: when the seismic force acting on a wall begins to exceed the wall's capacity, the wall undergoes displacement without absorbing the load exceeding its capacity, thereby plastifying and distributing the excess load — which would otherwise be imposed on it — to the other walls. To perform this calculation in the program, the stiffness multiplier of insufficient walls is reduced so that the shear force is not decreased by more than 25% (approximately 25% or less). In this case, due to the reduced stiffness, the wall carries less shear force and the program distributes the excess shear force that the wall does not carry to the other walls in proportion to their stiffnesses. Redistribution yields favourable results in situations where only a small number of walls are found to be insufficient by a small margin. In a structure where all walls are insufficient, it is difficult for redistribution to bring the structure to a satisfactory level.

Example Procedure Steps:

1 — An analysis is performed in the program without redistribution (without modifying the wall stiffness multipliers), and the report is saved as a PDF under the name "without redistribution."

2 — The stiffness multiplier or modulus of elasticity is reduced for insufficient walls in such a way that the shear force is not decreased by more than 25%.

3 — As a result of the analysis performed, it is checked whether the insufficient wall has become sufficient, whether the shear force in the insufficient wall has decreased by more than 25%, and whether the shear force in the other walls has exceeded an increase of 33%.

4 — If the conditions are satisfied, the calculation report is saved as "with redistribution." An explanatory technical report, together with the calculation reports with and without redistribution, is submitted to the authority.