Simple Code for Running CSI Sap 2000 from Matlab in Batch mode for finding Natural Frequency
%#########################################################################%
%# PROGRAMMER : MOHAMED SAJEER IBN AZAD MODAVAN #%
%# DATE : 03.09.2013(Last modified: 01:12:2015) #%
%# ABSTRACT : This Code used to Run SAP2000 from Matlab to find the #%
%# Natural frequency. This code may help you to adjest the #%
%# material properties to match the Natural frequency #%
%# of model with the actual value of Natural frequency. %#
%# Also you can use optimisation tool with this code for #%
%# finding optimum Design properties. #%
%#=======================================================================#%
%# Modifications may be required #%
%#=======================================================================#%
%# * Modify the version number of SAP2000 in line 31 #%
%# * This code required to modify for file path in line 40 #%
%# * In line 57 & 58 change the material name according to your model #%
%# * Material properties you can #%
%#########################################################################%
clear; clc; close all
% Material Properties
Eco = 20e6; % Modulus of Elasticity of Concrete
Est = 21e7; % Modulus of Elasticity of Steel
nu_c = 0.2; % Poisson's Ratio of Concrete
nu_s = 0.3; % Poisson's Ratio of Steel
% Pass data to Sap2000 as one-dimensional arrays
feature('COM_SafeArraySingleDim', 1);
% Pass non-scalar arrays to Sap2000 API by reference
feature('COM_PassSafeArrayByRef', 1);
% Create Sap2000 object
SapObject = actxserver('sap2000v15.SapObject'); % Version of Sap2000
% Start Sap2000 application
SapObject.ApplicationStart;
% Hide Application, Hide <=> Unhide
SapObject.Hide;
% Create SapModel object
Sap = SapObject.SapModel;
%%
% Open existing file
FilePath = 'D:\Frame'; % Location of Sap2000 Model
Sap.File.OpenFile([FilePath,'.sdb']);
%%
% Edit Model
% ----------
% Model lock =>(1)or unlock =>(0)
Sap.SetModelIsLocked(0);
% Switch to units
% lb_in_F = 01 lb_ft_F = 02 kip_in_F = 03 kip_ft_F = 04
% kN_mm_C = 05 kN_m_C = 06 kgf_mm_C = 07 kgf_m_C = 08
% N_mm_C = 09 N_m_C = 10 Ton_mm_C = 11 Ton_m_C = 12
% kN_cm_C = 13 kgf_cm_C = 14 N_cm_C = 15 Ton_cm_C = 16
Unit = 06;
Sap.SetPresentUnits(Unit);
% Assign isotropic mechanical properties
Sap.PropMaterial.SetMPIsotropic('Concrete', Eco, nu_c, 1.170E-05);
Sap.PropMaterial.SetMPIsotropic('Steel', Est, nu_s, 1.170E-05);
% Run model (this will create the analysis model)
Sap.Analyze.RunAnalysis();
% Set run case model
% Sap.Analyze.SetRunCaseFlag('MODAL', 1);
%%
% Results
% -------
% Count number of joints & DOF
countP = Sap.PointElm.Count;
DOF = countP*3-12;
disp('DEGREE OF FREEDOM');disp(DOF)
% Frequency
AA = fopen([FilePath,'.LOG'],'r');
Fr1 = fread(AA);
s = char(Fr1');
fclose(AA);
word1Location = strfind(s, 'NUMBER OF EIGEN MODES FOUND');
word2Location = strfind(s, 'NUMBER OF ITERATIONS PERFORMED');
TextLine = s(word1Location:word2Location-1);
Number_Modes = str2double(TextLine(54:end));
disp('NUMBER OF EIGEN MODES');disp(Number_Modes)
Frq = zeros(Number_Modes,1);
for ii = 1:Number_Modes
if ii == Number_Modes
word1Location = strfind(s, ['Found mode ' num2str(ii)]);
word2Location = strfind(s, 'NUMBER OF EIGEN MODES FOUND');
elseif ii < 9
word1Location = strfind(s, ['Found mode ' num2str(ii)]);
word2Location = strfind(s, ['Found mode ' num2str(ii+1)]);
elseif ii == 9
word1Location = strfind(s, ['Found mode ' num2str(ii)]);
word2Location = strfind(s, ['Found mode ' num2str(ii+1)]);
elseif (ii>9) && (ii~=Number_Modes)
word1Location = strfind(s, ['Found mode ' num2str(ii)]);
word2Location = strfind(s, ['Found mode ' num2str(ii+1)]);
end
Mode = s(word1Location:word2Location-1);
word1Location = strfind(Mode, 'f=');
word2Location = strfind(Mode, ', T= ');
Fre = Mode(word1Location:word2Location-1);
Freq = str2double(Fre(3:14));
Frq(ii,:) = Freq;
end
disp('FREQUENCY IN Hz');disp(Frq)
%%
% save model
Sap.File.Save([FilePath,'.sdb']);
%%
% close Sap2000
SapObject.ApplicationExit(false());
SapModel = 0;
SapObject = 0;
Cite As
Sajeer Modavan (2026). Simple Code for Running CSI Sap 2000 from Matlab in Batch mode for finding Natural Frequency (https://ch.mathworks.com/matlabcentral/fileexchange/54259-simple-code-for-running-csi-sap-2000-from-matlab-in-batch-mode-for-finding-natural-frequency), MATLAB Central File Exchange. Retrieved .
MATLAB Release Compatibility
Platform Compatibility
Windows macOS LinuxTags
Acknowledgements
Inspired: Matlab and SAP2000, Monte Carlo simulation for uncertainty propagation with SAP2000 OAPI and MATLAB
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