The error messages are listed as follow:
Modal Analysis and Gravity Analysis was achieved, and the calculated natural periods of the structure seems credible.WARNING BandGenLinLapackSolver;;solve<> -factorization failed, matrix singular U<i,i> = 0,i=62
WARNING AcceleratedNewton;; solveCurrentStep<> -the LinearSysOfEqun failed in solve<>
DirectIntegrationAnalysis;;analyze<> -the Algorithm failed at time 4.12
OpenSees > analyze failed, returned; -3 error flag
The following describes the details of my model, and analysis settings:
1) A 2-dimesion and 3-DOF concrete frame model. At each beam 5 elements were used, both of the elements were disp-based nonlinear elements with 2 different materials. At the joint region of each joint, 4 zero-length elements were used, and righdlinks were also assigned to the region. Prestressed strands were also set using truss elements.
2) the earthquake analysis setting are as follows:
constraints Transformation;
numberer RCM
system BandGeneral;
test NormDispIncr 1.e-5 200 0
integrator Newmark 0.5 0.25
And 3 algorithms were used: firstly try KrylovNewton, if failed then try Newton -initial method, if filaed again then try Broyden or NewtonLineSearch.
The failure occurs at the beginning (e.g. 4.12s shown above) of the domain where the PGA is not so large (e.g. 1g).