*HEADING
SDOF PROBLEM: SPRINGS, SOLID ELEMENTS AND POINT LOADS
**
*NODE,NSET=ALL
101,0.,0.
102,1.,0.
103,1.,1.
104,0.,1.
105,0.,-1.
106,1.,-1.
201,1.5,0.
202,2.5,0.
203,2.5,1.
204,1.5,1.
205,1.5,-1.
206,2.5,-1.
301,3.,0.
302,4.,0.
303,4.,1.
304,3.,1.
305,3.,-1.
306,4.,-1.
401,0.,2.5
402,1.,2.5
403,1.,3.5
404,0.,3.5
405,0.,1.5
406,1.,1.5
501,1.5,2.5
502,2.5,2.5
503,2.5,3.5
504,1.5,3.5
505,1.5,1.5
506,2.5,1.5
601,3.,2.5
602,4.,2.5
603,4.,3.5
604,3.,3.5
605,3.,1.5
606,4.,1.5
*NSET,NSET=FIX
105,106,205,206,305,306,405,406,505,506,605,606
*ELEMENT,TYPE=CPE4R,ELSET=SOLID
1, 101,102,103,104
2, 201,202,203,204
3, 301,302,303,304
4, 401,402,403,404
5, 501,502,503,504
6, 601,602,603,604
*ELEMENT,TYPE=SPRINGA,ELSET=LSPRING
101, 105,101
102, 106,102
301, 305,301
302, 306,302
401, 405,401
402, 406,402
*ELEMENT,TYPE=SPRINGA,ELSET=NSPRING1
201, 205,201
202, 206,202
601, 605,601
602, 606,602
*ELEMENT,TYPE=SPRINGA,ELSET=NSPRING2
501, 505,501
502, 506,502
*ELEMENT,TYPE=DASHPOTA,ELSET=DDD
701, 605,601
*DASHPOT,ELSET=DDD,NONLINEAR,RTOL=0.02

-1E6,-100.
-1E5,-10.
-1E4,-1.
0.,0.
1E4,1.
1E5,10.
1E6,100.
*ELEMENT,TYPE=MASS,ELSET=PT
405, 401
406, 402
*MASS,ELSET=PT
500.,
*SPRING,ELSET=LSPRING

2.E6, 
** non-linear spring 1 has the same linear stiffness
** as the linear springs
*SPRING,ELSET=NSPRING1,NONLINEAR

-2.E7,-10.
 2.E7, 10.
** non-linear spring 2 has the same linear stiffness as the linear
** springs up to the static equilibrium displacement and 20% of
** the linear stiffness past that point
*SPRING,ELSET=NSPRING2,NONLINEAR,RTOL=0.02

-.9E6, -1.25
-.5E6, -0.25
 .5E6,  0.25
 .9E6,  1.25
*SOLID SECTION,ELSET=SOLID,MATERIAL=TEST
*MATERIAL,NAME=TEST
*DENSITY
1000., 
*ELASTIC
1.E9,0.
*BOUNDARY
ALL,1,1
FIX,1,3
*RESTART,TIMEMARKS=YES,WRITE,NUMBER INTERVAL=1
**
*NSET, NSET=QA_TEST_ALLNODES
ALL, FIX
**
*STEP
*DYNAMIC,EXPLICIT
 ,.1405
*CLOAD
201,2,-.5E6
202,2,-.5E6
601,2,-.5E6
602,2,-.5E6
*DLOAD
1,P3,1.E6
3,GRAV,1000.,0.,-1.,0.
4,P3,1.E6
5,P3,1.E6
***OUTPUT,HISTORY,TIME INTERVAL=0.0
***ELEMENT OUTPUT,ELSET=LSPRING
**E11,
***ENERGY OUTPUT
**ALLKE,ALLIE,ALLAE,ALLVD,ALLWK,ETOTAL,
**DT,
**
*FILE OUTPUT,NUMBER INTERVAL=1,TIMEMARKS=YES
*NODE FILE
U
*OUTPUT, FIELD, NUMBER INTERVAL=1, TIMEMARKS=YES
*NODE OUTPUT, NSET=QA_TEST_ALLNODES
U
*OUTPUT,FIELD,VARIABLE=PRESELECT
*OUTPUT,HISTORY,VARIABLE=PRESELECT,TIMEINT=0.1405
*END STEP