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by elescher
Mon Dec 20, 2021 6:48 am
Forum: OpenSees.exe Users
Topic: Force-displacement plot not starting from zero
Replies: 0
Views: 11621

Force-displacement plot not starting from zero

I am running a code for a 3D bridge and my transverse force-displacement plot is not starting from zero, but my longitudinal force-displacement plot is. If I turn off the gravity loading and just apply the masses to each node, the plots look fine, but the transverse direction starts at 6.1 kips when I apply linear gravity load. Here is the part of the code for gravity analysis (units are kips and inches):

Code: Select all

 
 #Define Gravity Load and Analysis
#================================

#Define Loads
set g 386.4;									#gravity (in/s2)
set WtCol [expr -37.*$kip];					#Total weight per column (kip)
set WtBeam [expr -210.*$kip];					#Total weight of cap beam (kip)
set WtSAP [expr -1794.*$kip];					#Total weight of panels + girders from SAP2000 (kip)
set WtDeck [expr $WtSAP]; 						#Total deck weight to be distributed to nodes (kip)
set NumNodes 40;								#number of bridge nodes for lumping mass *39 nodes and end nodes use 1/2 load
set DNodeLoad [expr $WtDeck/$NumNodes]; 		#Load at deck nodes
set BNodeLoad [expr $WtBeam/10.];					#beam weight distributed over nodes  *9 nodes and end nodes use 1/2 load
set CNodeLoad [expr $WtCol/2.]; 					#Load at bottom column nodes *2 nodes per column

#Define Masses 
set CNodeMass [expr abs($CNodeLoad/$g)];		#Lumped mass at column nodes
set BNodeMass [expr abs($BNodeLoad/$g)];		#Lumped mass at beam nodes
set DNodeMass [expr abs($DNodeLoad/$g)];		#Lumped mass at deck nodes

#mass nodetag Mx My Mz MRx MRy MRz
#Column Nodes
mass 63373 $CNodeMass $CNodeMass $CNodeMass 0 0 0;
mass 63374 $CNodeMass $CNodeMass $CNodeMass 0 0 0;

#Beam Nodes
mass 63375 [expr $BNodeMass/2.] [expr $BNodeMass/2.] [expr $BNodeMass/2.] 0 0 0; #1/2 beam 
mass 63376 $BNodeMass $BNodeMass $BNodeMass 0 0 0;
mass 63377 [expr $CNodeMass+$BNodeMass] [expr $CNodeMass+$BNodeMass] [expr $CNodeMass+$BNodeMass] 0 0 0;  # Beam + column
mass 63378 $BNodeMass $BNodeMass $BNodeMass 0 0 0;
mass 63379 $BNodeMass $BNodeMass $BNodeMass 0 0 0;
mass 63380 [expr $DNodeMass+$BNodeMass] [expr $DNodeMass+$BNodeMass] [expr $DNodeMass+$BNodeMass] 0 0 0; #deck + beam
mass 63381 $BNodeMass $BNodeMass $BNodeMass 0 0 0;
mass 63382 $BNodeMass $BNodeMass $BNodeMass 0 0 0;
mass 63383 [expr $CNodeMass+$BNodeMass] [expr $CNodeMass+$BNodeMass] [expr $CNodeMass+$BNodeMass] 0 0 0;  # Beam + column
mass 63384 $BNodeMass $BNodeMass $BNodeMass 0 0 0;
mass 63385 [expr $BNodeMass/2.] [expr $BNodeMass/2.] [expr $BNodeMass/2.] 0 0 0; #1/2 beam 

#Deck Nodes
#SPAN 1
mass 63386	[expr $DNodeMass/2.] [expr $DNodeMass/2.] [expr $DNodeMass/2.] 0 0 0; #1/2 deck
mass 63387	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63388	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63389	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63390	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63391	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63392	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63393	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63394	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63395	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63396	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63397	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63398	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63399	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63400	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63401	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63402	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63403	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63404	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63405	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
#SPAN 2
mass 63406	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63407	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63408	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63409	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63410	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63411	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63412	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63413	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63414	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63415	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63416	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63417	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63418	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63419	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63420	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63421	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63422	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63423	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63424	$DNodeMass $DNodeMass $DNodeMass 0 0 0;
mass 63425	[expr $DNodeMass/2.] [expr $DNodeMass/2.] [expr $DNodeMass/2.] 0 0 0; #1/2 deck

puts "Masses Defined"

#create load pattern for gravity load
pattern Plain 1 Linear {
#Column Nodes, concentrated in the y-direction
load 63373 0 $CNodeLoad 0 0 0 0;
load 63374 0 $CNodeLoad 0 0 0 0;

#Beam Nodes
load 63375 0 [expr $BNodeLoad/2] 0 0 0 0;				#1/2 beam load
load 63376 0 $BNodeLoad 0 0 0 0;
load 63377 0 [expr $CNodeLoad +$BNodeLoad] 0 0 0 0;	# Beam + column 
load 63378 0 $BNodeLoad 0 0 0 0;
load 63379 0 $BNodeLoad 0 0 0 0;
load 63380 0 [expr $BNodeLoad+$DNodeLoad] 0 0 0 0;	# Midspan node 
load 63381 0 $BNodeLoad 0 0 0 0;
load 63382 0 $BNodeLoad 0 0 0 0;
load 63383 0 [expr $CNodeLoad +$BNodeLoad] 0 0 0 0;	# Beam + column
load 63384 0 $BNodeLoad 0 0 0 0;
load 63385 0 [expr $BNodeLoad/2] 0 0 0 0;				#1/2 beam load

#Deck Nodes, concentrated in the y-direction
#SPAN 1
load 63386	0 [expr $DNodeLoad/2.] 0 0 0 0;				#1/2 deck load
load 63387	0 $DNodeLoad 0 0 0 0;
load 63388	0 $DNodeLoad 0 0 0 0;
load 63389	0 $DNodeLoad 0 0 0 0;
load 63390	0 $DNodeLoad 0 0 0 0;
load 63391	0 $DNodeLoad 0 0 0 0;
load 63392	0 $DNodeLoad 0 0 0 0;
load 63393	0 $DNodeLoad 0 0 0 0;
load 63394	0 $DNodeLoad 0 0 0 0;
load 63395	0 $DNodeLoad 0 0 0 0;
load 63396	0 $DNodeLoad 0 0 0 0;
load 63397	0 $DNodeLoad 0 0 0 0;
load 63398	0 $DNodeLoad 0 0 0 0;
load 63399	0 $DNodeLoad 0 0 0 0;
load 63400	0 $DNodeLoad 0 0 0 0;
load 63401	0 $DNodeLoad 0 0 0 0;
load 63402	0 $DNodeLoad 0 0 0 0;
load 63403	0 $DNodeLoad 0 0 0 0;
load 63404	0 $DNodeLoad 0 0 0 0;
load 63405	0 $DNodeLoad 0 0 0 0;
#SPAN 2
load 63406	0 $DNodeLoad 0 0 0 0;
load 63407	0 $DNodeLoad 0 0 0 0;
load 63408	0 $DNodeLoad 0 0 0 0;
load 63409	0 $DNodeLoad 0 0 0 0;
load 63410	0 $DNodeLoad 0 0 0 0;
load 63411	0 $DNodeLoad 0 0 0 0;
load 63412	0 $DNodeLoad 0 0 0 0;
load 63413	0 $DNodeLoad 0 0 0 0;
load 63414	0 $DNodeLoad 0 0 0 0;
load 63415	0 $DNodeLoad 0 0 0 0;
load 63416	0 $DNodeLoad 0 0 0 0;
load 63417	0 $DNodeLoad 0 0 0 0;
load 63418	0 $DNodeLoad 0 0 0 0;
load 63419	0 $DNodeLoad 0 0 0 0;
load 63420	0 $DNodeLoad 0 0 0 0;
load 63421	0 $DNodeLoad 0 0 0 0;
load 63422	0 $DNodeLoad 0 0 0 0;
load 63423	0 $DNodeLoad 0 0 0 0;
load 63424	0 $DNodeLoad 0 0 0 0;
load 63425	0 [expr $DNodeLoad/2.] 0 0 0 0;				#1/2 deck load
}
puts "Loads Defined"

constraints Plain;                 # how it handles boundary conditions (single and multi-point constraints)
numberer RCM;			             		# renumber dof's to minimize band-width (optimization)
system BandGeneral;		                	# how to store and solve the system of equations in the analysis

#Convergence Test
set TestTypeGravity NormDispIncr;	        # Convergence Test: type
set TolGravity 1.0e-10;		      			# Convergence Test: tolerance
set maxNumIterGravity 10;             		# Convergence Test: max number of iterations
set printFlagGravity 0;		      			# Convergence Test: flag used to print information on convergence (optional)        # 1: print information on each step; 
test $TestTypeGravity $TolGravity $maxNumIterGravity $printFlagGravity;

#Integrator
set NstepGravity 10;  		          		# apply gravity in 20 steps
set DGravity [expr 1./$NstepGravity]; 		# Gravity load increment;
integrator LoadControl 0.1;	  		# Determine the next time step for an analysis

#Algorithm
set algorithmTypeGravity Linear;      		# use Newton's solution algorithm: updates tangent stiffness at every iteration
algorithm $algorithmTypeGravity;

#Analysis
set  InTG [clock microseconds]
analysis Static;		              		# define type of analysis static or transient
analyze $NstepGravity;		         		# Apply Gravity load

set FiTG [clock microseconds]
set ComT [expr ($FiTG-$InTG)/1.e6]
puts "Computational time for Gravity Analysis: $ComT"
by elescher
Mon Mar 01, 2021 2:00 pm
Forum: OpenSees.exe Users
Topic: Composite Section Using Two Elements
Replies: 1
Views: 2250

Composite Section Using Two Elements

I am trying to develop a simple stick model for a bridge deck with a concrete slab and steel girders. Is it possible to define two different elements between two nodes? I want to define one element with the concrete section and one with the girder section properties. If this is possible, are there any commands that need to be defined in order for the elements to work as a composite section?

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