etabs plus and sequential construction case 1

[joanrizu]

I am designing a building without a column in the first story. I´ve found that if I run an elastic analysis and then I define a sequential construction case, etabs plus v.909 makes an analysis and gives results that makes sense. But I am not sure that etabs plus results are correct, because manual refers to etabs nonlinear when you ask about sequential construction. Could some body tell me more about this topic.

 

[stressed]

I believe you need to have ETABS nonlinear version to run a sequential construction analysis. However, when you first install ETABS, it defaults for some time period (30 days?) nonlinear version, even if you purchased a lesser version, or until you get a permanent license file. I assume that you went under the Define menu to Add a sequential construction case. The thing is, with ETABS, to do sequential construction, you must make two analyses. First run your regular analysis, then you have go back again under the Analyze menu to run the Contruction sequence nonlinear analysis. In your situation where you are using a tranfer girder on the first story, that is a typical application where the stage construction might give some insightful results compared to a linear Dead case analysis. Keep in mind that ETABS stage construction (to my knowledge) is only additive, in that you can add stories and/or groups, but not remove elements or group as part of the sequential construction analysis. good luck.

 

[joanrizu]

I think Etabs Plus has an open
door to the sequential analysis if you define the
dead-sq after you run the static analysis, that is the
statement I wrote by first. Please follow this steps
with any model you have: delete any dead-sq case, run
static analysis, define a dead-sq case, run the
sequential construction case, and you will obtain this
analysis run log:

Program ETABS Version 9.0.9.0 File:modelo secuencial similar al tutorial.LOG

BLOQUE 5


B E G I N A N A L Y S I S 2006/08/18 22:58:53

MAXIMUM MEMORY BLOCK SIZE (BYTES) = 31.962 MB


E L E M E N T F O R M A T I O N 22:58:53

NUMBER OF JOINT ELEMENTS FORMED = 79
NUMBER OF SPRING ELEMENTS FORMED = 0
NUMBER OF FRAME ELEMENTS FORMED = 159


E Q U A T I O N S O L U T I O N 22:58:53

TOTAL NUMBER OF EQUILIBRIUM EQUATIONS = 207
APPROXIMATE "EFFECTIVE" BAND WIDTH = 33

NUMBER OF EQUATION STORAGE BLOCKS = 1
MAXIMUM BLOCK SIZE (8-BYTE TERMS) = 6447
SIZE OF STIFFNESS FILE(S) (BYTES) = 51.191 KB

NUMBER OF EQUATIONS TO SOLVE = 207
NUMBER OF STATIC LOAD CASES = 4
NUMBER OF ACCELERATION LOADS = 6
NUMBER OF NONLINEAR DEFORMATION LOADS = 0


J O I N T O U T P U T 22:58:53

G L O B A L F O R C E B A L A N C E R E L A T I V E E R R O R S

PERCENT FORCE AND MOMENT ERROR AT THE ORIGIN, IN GLOBAL COORDINATES

LOAD FX FY FZ MX MY MZ
DEAD 3.26E-15 .000000 1.18E-13 0.478953 6.80E-14 0.015486
TRIBUTAR .000000 .000000 .000000 .000000 .000000 .000000
SX .000000 .000000 .000000 .000000 .000000 .000000
SY .000000 .000000 .000000 .000000 .000000 .000000

SPEC FX FY FZ MX MY MZ
SX .000000 .000000 .000000 .000000 .000000 .000000
SY .000000 .000000 .000000 .000000 .000000 .000000


E L E M E N T J O I N T - F O R C E O U T P U T 22:58:53

NUMBER OF JOINT ELEMENTS SAVED = 79
NUMBER OF FRAME ELEMENTS SAVED = 159


E L E M E N T O U T P U T 22:58:53



A N A L Y S I S C O M P L E T E 2006/08/18 22:58:53


Program ETABS Version 9.0.9.0 File:modelo secuencial similar al tutorial.LOG

BLOQUE 5


B E G I N A N A L Y S I S 2006/08/18 22:58:54

MAXIMUM MEMORY BLOCK SIZE (BYTES) = 31.962 MB


E L E M E N T F O R M A T I O N 22:58:54

NUMBER OF JOINT ELEMENTS FORMED = 79
NUMBER OF SPRING ELEMENTS FORMED = 0


L O A D R E - S O L U T I O N 22:58:54

NUMBER OF STATIC LOAD CASES = 4


E L E M E N T J O I N T - F O R C E O U T P U T 22:58:55

NUMBER OF JOINT ELEMENTS SAVED = 79
NUMBER OF FRAME ELEMENTS SAVED = 159


A N A L Y S I S C O M P L E T E 2006/08/18 22:58:55


Program ETABS Version 9.0.9.0 File:modelo secuencial similar al tutorial.LOG

BLOQUE 5


N O N L I N E A R S T A T I C A N A L Y S I S 2006/08/18 22:59:28

MAXIMUM MEMORY BLOCK SIZE (BYTES) = 31.962 MB

NONLINEAR STATIC CASE = DEAD-SQ
CONTINUE FROM PREVIOUS CASE = 0

LOAD CONTROL TYPE = FORCE
METHOD TO USE WHEN HINGES DROP LOAD = UNLOAD
TYPE OF GEOMETRIC NONLINEARITY = NONE
SAVE POSITIVE INCREMENTS ONLY = YES

MINIMUM NUMBER OF SAVED STEPS = 1
MAXIMUM NUMBER OF SAVED STEPS = 50
MAXIMUM NUMBER OF NULL STEPS = 50
MAXIMUM NUMBER OF TOTAL STEPS = 200
MAXIMUM NUMBER OF ITERATIONS PER STEP = 10

RELATIVE FORCE CONVERGENCE TOLERANCE = 0.000100
RELATIVE EVENT TOLERANCE = 0.010000

STAGE NUMBER = 1
ENTIRE STRUCTURE IS ACTIVE = NO
CHANGES TO ELEMENTS IN STRUCTURE = NONE

STEP 0

STEP 1, INCREMENT = 1.000000, SUM = 1.000000, MAX = 1.000000

Unbalance/tolerance = 4.39E-12, Iteration 1 converged
Saved as Output Step 1

TOTAL NUMBER OF CONVERGED STEPS SAVED = 1
TOTAL NUMBER OF CONVERGED STEPS NOT SAVED = 0
TOTAL NUMBER OF NULL STEPS = 0
----------
TOTAL NUMBER OF ALL STEPS = 1

TOTAL NUMBER OF ITERATIONS CONVERGED = 1
TOTAL NUMBER OF ITERATIONS DISCARDED = 0
FOR CONVERGED STEPS ONLY:
AVERAGE NUMBER OF ITERATIONS PER STEP = 1.00
MAXIMUM NUMBER OF ITERATIONS PER STEP = 1

STAGE NUMBER = 2
ENTIRE STRUCTURE IS ACTIVE = NO
CHANGES TO ELEMENTS IN STRUCTURE = ADD ONLY


STEP 0

STEP 1, INCREMENT = 1.000000, SUM = 1.000000, MAX = 1.000000

Unbalance/tolerance = 6.65E-11, Iteration 1 converged
Saved as Output Step 1

TOTAL NUMBER OF CONVERGED STEPS SAVED = 1
TOTAL NUMBER OF CONVERGED STEPS NOT SAVED = 0
TOTAL NUMBER OF NULL STEPS = 0
----------
TOTAL NUMBER OF ALL STEPS = 1

TOTAL NUMBER OF ITERATIONS CONVERGED = 1
TOTAL NUMBER OF ITERATIONS DISCARDED = 0
FOR CONVERGED STEPS ONLY:
AVERAGE NUMBER OF ITERATIONS PER STEP = 1.00
MAXIMUM NUMBER OF ITERATIONS PER STEP = 1

STAGE NUMBER = 3
ENTIRE STRUCTURE IS ACTIVE = NO
CHANGES TO ELEMENTS IN STRUCTURE = ADD ONLY


STEP 0

STEP 1, INCREMENT = 1.000000, SUM = 1.000000, MAX = 1.000000

Unbalance/tolerance = 6.47E-11, Iteration 1 converged
Saved as Output Step 1

TOTAL NUMBER OF CONVERGED STEPS SAVED = 1
TOTAL NUMBER OF CONVERGED STEPS NOT SAVED = 0
TOTAL NUMBER OF NULL STEPS = 0
----------
TOTAL NUMBER OF ALL STEPS = 1

TOTAL NUMBER OF ITERATIONS CONVERGED = 1
TOTAL NUMBER OF ITERATIONS DISCARDED = 0
FOR CONVERGED STEPS ONLY:
AVERAGE NUMBER OF ITERATIONS PER STEP = 1.00
MAXIMUM NUMBER OF ITERATIONS PER STEP = 1

STAGE NUMBER = 4
ENTIRE STRUCTURE IS ACTIVE = YES
CHANGES TO ELEMENTS IN STRUCTURE = ADD ONLY


STEP 0

STEP 1, INCREMENT = 1.000000, SUM = 1.000000, MAX = 1.000000

Unbalance/tolerance = 4.59E-11, Iteration 1 converged
Saved as Output Step 1

TOTAL NUMBER OF CONVERGED STEPS SAVED = 1
TOTAL NUMBER OF CONVERGED STEPS NOT SAVED = 0
TOTAL NUMBER OF NULL STEPS = 0
----------
TOTAL NUMBER OF ALL STEPS = 1

TOTAL NUMBER OF ITERATIONS CONVERGED = 1
TOTAL NUMBER OF ITERATIONS DISCARDED = 0
FOR CONVERGED STEPS ONLY:
AVERAGE NUMBER OF ITERATIONS PER STEP = 1.00
MAXIMUM NUMBER OF ITERATIONS PER STEP = 1

STAGE NUMBER = 5
ENTIRE STRUCTURE IS ACTIVE = YES
CHANGES TO ELEMENTS IN STRUCTURE = NONE

STEP 0

* * * W A R N I N G * * *
THE APPLIED LOAD IS ZERO IN NONLIN-STATIC CASEDEAD-SQ ,
THE ANALYSIS WILL PROCEED BUT THE STRUCTURE WILL NOT BE LOADED


STEP 1, INCREMENT = 1.000000, SUM = 1.000000, MAX = 1.000000

Unbalance/tolerance = .000000, Iteration 1 converged
Saved as Output Step 1

TOTAL NUMBER OF CONVERGED STEPS SAVED = 1
TOTAL NUMBER OF CONVERGED STEPS NOT SAVED = 0
TOTAL NUMBER OF NULL STEPS = 0
----------
TOTAL NUMBER OF ALL STEPS = 1

TOTAL NUMBER OF ITERATIONS CONVERGED = 1
TOTAL NUMBER OF ITERATIONS DISCARDED = 0
FOR CONVERGED STEPS ONLY:
AVERAGE NUMBER OF ITERATIONS PER STEP = 1.00
MAXIMUM NUMBER OF ITERATIONS PER STEP = 1

TIME FOR INITIALIZING ANALYSIS = 0.03
TIME FOR CONTROLLING ANALYSIS = 1.14
TIME FOR FORMING STIFFNESS MATRIX = 0.07
TIME FOR SOLVING STIFFNESS MATRIX = 0.24
TIME FOR CALCULATING DISPLACEMENTS = 0.00
TIME FOR DETERMINING EVENTS = 0.00
TIME FOR UPDATING STATE = 0.04
----------
TOTAL TIME FOR THIS ANALYSIS = 1.52


A N A L Y S I S C O M P L E T E 2006/08/18 22:59:30