Design - Software - REXEL

30/09/2014:REXEL 3.5 has been released. REXEL allows to define the design spectra according to the Eurocode 8, the new Italian Building Code or completely user-defined. Based on these spectra, the software allows to search for sets of 1, 7, or 30 records compatible, in the average, with them. Records may also reflect the seismogenetic features of the sources (in terms of magnitude and epicentral distance), ground motion intensity measures, and soil conditions appropriate to the site. The datasets contained in REXEL are the European Strong-motion Database (ESD), the Italian Accelerometric Archive (ITACA) (for a table of matching between ITACA records and the accelerograms IDs in REXEL see here), and the Selected Input Motions for displacement-Based Assessment and Design (SIMBAD).

For details about updates and a track of changes of older versions see the change log.

Design - Software - REXEL-DISP

31/01/2013: REXEL-DISP 1.2 beta HAS BEEN RELEASED. REXEL-DISP allows to select suites of natural accelerograms compatible with displacement spectra of NTC ’08, EC8, deriving from an ad-hoc hazard analysis of INGV-DPC S5 research project, or user defined. Records contained in REXEL-DISP are those of: Selected Input Motions for Displacement-Based Assessment and Design (SIMBAD).

For details about updates and a track of changes of older versions see the change log.


REXEL and REXEL-DISP were developed in MATLAB environment; for its use the MATLAB Component Runtime (MCR) 711 is required. Please launch preliminarily the MCRInstaller.exe file and follow the instructions of the installation procedure. REXEL requires a specific version of MATLAB. If you have a different version of MATLAB, REXEL will not work; for this reason, you must install the MCR. It is recommended to restart the computer after installing MCR. The MATLAB Component Runtime is a free redistributable that allows you to run programs written in a specific version of MATLAB without installing the MATLAB version itself. There is no harm in having MATLAB and the MCR installed simultaneously, or in having multiple versions of each one installed. The first run of REXEL may take some minutes, please wait patiently, it works!

Footnote 1 (for Windows Vista and Windows 7 users): May be some problems in running REXEL (and REXEL-DISP) after install on computers using Windows Vista or 7 (or later versions). In fact, it may be required to disable the the “user account control” (UAC) features. To do so right-click on the REXEL .exe file, then choose properties and disable the UAC. After that REXEL should run without further problems. More easily it is possible to right-click  and select to run as an administrator in the context menu.
Footnote 2: REXEL was developed on Windows XP, it works on more recent Windows OS’. However, it may be required to install the following windows component to allow REXEL to start. Please install this file if at startup only a black window appears for short time and REXEL does not start..
Footnote 3: On some operating systems the computation of deviations in REXEL may be especially slow. In any case the software is optimized for Windows XP.
Footnote 4: Please recall that REXEL returns records in m/s^2 units.


REXEL and REXEL-DISP are licensed under a Creative Commons Attribution – No Derivative Works 3.0 Unported License.
Based on a work at
Permissions beyond the scope of this license may be available at

For information on REXEL and REXEL-DISP please contact
Iunio Iervolino  (
Department of Structures for Engineering and Architecture, University of Naples Federico II
Via Claudio 21, 80125 Naples (Italy)
Phone: +39 081.7683488, Fax: +39 081.7685921

Disclaimer: REXEL and REXEL-DISP may be used and distributed for free while their modification and commercialization are not authorized. The authors have made every effort in order to ensure the accurate working of the software; however, any responsibility is declined for wrong results.




Frequently Asked Questions

0. Make sure that you are running REXEL as an administrator.

1. Q. After installing the program, when starting the program in the black background screen it appears:

  • cannot find C:\program files\rexel 3.5\spectrum_imput.txt
  • impossible to find C:\program files\rexel 3.5\data.txt
  • impossible to find C:\program files\rexel 3.5\data_no_ord.txt
  • impossible to find C:\program files\rexel 3.5\comb_out.txt
  • impossible to find C:\program files\rexel 3.5\ric_spec.txt

how to solve the problem?

1. A. It is not a problem, simply REXEL checks to delete any remnants of previous analyses before running a new one; it also does this check at first startup when these files do not exist. It is a sign of correct installation of the program.

2. Q. Once all the data are entered and processing is started, the program processes for a long time but nothing happens.

2. A. When you pre-select many accelerograms (e.g., one hundred or more) the number of combinations REXEL has to analyze is many billions (the number of combinations grows with the binomial coefficient as a function of the number of pre-selected waveforms). So, it is normal for the analysis to take a long time (even days or weeks). It is strongly recommended to limit the number of waveforms in which to search from the preliminary database search. Note that this problem is clearly discussed in the tutorial, in the bibliography, and there is a pop-up that appears in REXEL when you pre-select more than a hundred records.

3. Q. Once all the parameters for a certain site are entered, REXEL does not find any combination that meets the criteria, despite having also met the disaggregation criteria. How can I solve the problem?

3. A. Although it is not particularly frequent, it may be that no solution to a particular search exists in the databases included in REXEL. As described in the tutorial, in such cases it is necessary to change, or at least widen, the intervals in which accelerograms are pre-selected, or to increase the allowable scaling factor for records in case they are searched scaled. In general, the ‘preliminary plot’ gives an idea whether solutions will be found, or whether it is convenient to scale the accelerograms. As a last resort, one can use REXELweb, which, by operating on a continuously updated database, can provide additional opportunities.

4. Q. REXEL performs the analysis for a certain condition, but then does not return the results. How to solve the problem?

4. A. REXEL needs Microsoft EXCEL and Winzip to be able to return results. (NB: EXCEL must also be run as administrator.)

5. Q. REXEL performs the analysis for a certain condition, but then does not return the results. How to solve the problem?

5. A. REXEL needs the decimal separator in Windows to be a period and not a comma. One should make sure that in the international and language settings of Windows this choice is made.

6. Q. I entered the user-defined spectrum in the EXCEL sheet that opens in REXEL, but then the program goes into error. Why?

6. A. The user-defined spectrum must be entered only to the periods that appear in the first column of the EXCEL sheet. You cannot enter spectral ordinates for arbitrary periods. See also Q. 5.

7. Q. I have Microsoft Windows 64-bit operating system and REXEL cannot even start. How to solve the problem?

7. A. REXEL is a 32bit compiled program, while it may be that OFFICE is 64bit on a computer with a 64bit operating system. In that case, OFFICE and REXEL need to be in the same Windows program folder (see also the note in red above on this same page).

8. Q. I have Windows Vista or Windows 7 (or later) and the program does not start; an error appears that has to do with MATLAB Compiler Runtime or mclmcr.dll. What can I do about this?

8. A. Make sure you have downloaded and installed MCR_Installer.exe before installing REXEL.

9. Q. Are the accelerograms in REXEL already scaled?

9. A. The units accelerograms in REXEL is m/s^2 and the accelerograms are provided unscaled, so if you have searched for scaled accelerograms they should be multiplied by the scaling factor provided by REXEL before being used.

10. Q. I have a Mac computer (or Linux) is there a version of REXEL for this operating system?

10. A. No, to run REXEL on other operating systems you need to install virtual machines such as Virtualbox or Parallels.

11. Q. I am performing a local seismic response analysis….

11. A. REXEL was developed with structural engineering applications in mind, namely analysis of structures. In addition, REXEL is a software product of research activities. It is strictly necessary to delve into the scientific bibliography related to REXEL (see above) in order to avoid misuse.

12. Q. I have a problem that is not among those discussed. What can I do about it?

12. A. It is recommended that you study the REXEL tutorial and bibliography before using it. In addition to being necessary to use the program correctly and understand its results, it is likely that the problem in question is discussed in the documentation. If none of these alternatives solve the problem you may want to use REXELweb or contact the developers at the addresses below.

13. Q. The Italian code (circular 2018) suggests new selection criteria, so REXEL’s are no longer okay?

13. A. No, in fact they continue to be fine. We recommend that you learn more about this issue by reading the following paper on the subject:

14. Q. I have Windows Vista or Windows 7 (or later) and the program won’t start; a black window opens but closes immediately. What can I do about this?

14. A. REXEL was developed on Windows XP, but was found to work properly on all other Microsoft operating systems up to 10. In some cases, it is missing a Windows component that can be obtained by installing this file. Installing this component should solve the problem, but if not, we have no solution other than to follow all installation instructions carefully.

15. Q. When searching for sets that include both horizontal and vertical components, the ‘Spectrum matching parameters and analysis options.txt’ file related to the vertical spectrum does not correctly report the tolerance parameters and periods to which the vertical spectral compatibility refers, why?

15. A. It is a REXEL bug in returning the outputs, but the calculations are correct. The actual vertical spectral compatibility parameters used in the search are correctly coded in the output figures and in the file in the ‘REXEL v 3.5’ folder called COMB_OUT(V).txt (or ‘COMB_OUTV.txt’).