Numerical Methods for Nonlinear Analysis
Load Incremental Schemes
It describes the solution method for control of load increment size. There are five methods to be selected.
It describes the solution method for control of load increment size. There are five methods to be selected.
In the process of time history analysis by NIDA, a simple, accurate and efficient method for determining the plastic hinge(s) is used to capture the progressive strength and stiffness degradation of the structure under an earthquake attack.
Nida checks the section capacity along the length of every initially curved member for P-δ effect, which is required by design code for member imperfection and member second-order effect. Other software only check the P-Δ effect at element ends which is inadequate for full second-order analysis. As the P-Δ and the P-δ effects have been considered in Nida, no effective length or λcr factor is required to be determined.
A semi-rigid connection must have the required strength, stiffness and ductility. Some typical moment versus rotation (M-θ) curves and various analytical and mathematical models representing the M-θ relationships can be found in previous chapters. Conveniently, a joint can be considered in an analysis as dimensionless with location at the intersection of the element centre lines. Further, a rotational spring element satisfying the M-θ relationship is inserted into each end of beam element to model the connection behaviour. The joint equilibrium condition can be expressed as,