Pedestrian Steel Footbridge OMA Dataset Recorded with Accelerometers and Strain Gauges

🏛️Overview

This repository contains a self-contained full-scale OMA dataset from a steel pedestrian footbridge in Granada (Spain), including multi-setup accelerometer recordings and strain-gauge measurements acquired in two field campaigns, together with the corresponding OMA identification outputs, channel location definitions, and the SAP2000 finite element model used for EfI-based sensor placement and modal comparison.

🧩Repository contents

• Description.pdf: file with a description of the structure, monitoring campaigns, instrumentation, signal processing, and modal identification settings.
• Channels_locations.pdf: overview of sensor locations, including the layout for each accelerometer setup (reference and roving sensors) and the strain-gauge locations on the main truss.
• footbridge-uncalibrated.sdb: SAP2000 FE model of the footbridge used to compute numerical modal properties and support EfI-based sensor placement and modal comparisons.
• time_series: folder containing accelerometer and strain-gauge time series provided as plain text matrices (one column per sensor channel; no time column; no header). The channel order matches the CHANNELS list in the corresponding *_modal_results_*.txt file:
  • time_series/acc_raw_time_series_Setup_i_1600Hz.txt: raw accelerometer time series for setup i (sampling frequency: 1600 Hz, units: g).
  • time_series/sg_raw_time_series_84_23_Hz.txt: raw strain-gauge time series from the strain campaign (sampling frequency: 84.23 Hz, units: m/m).
  • time_series/sg_filtered_time_series_84_23_Hz.txt: Processed (filtered) strain-gauge time series from the strain campaign (sampling frequency: 84.23 Hz, units: m/m). Processed strain-gauge signals include spike removal, detrending, and 2–30 Hz band-pass Butterworth filtering (see Description.pdf, Section 3).
• modal_data: OMA outputs exported from the MOVA software for each case:
  • modal_data/acc_Modal_Results_Setup_i.txt: OMA identification results for accelerometer setup i (COV-SSI). The file includes: (a) a summary table with identified modal frequency and damping ratios, (b) the CHANNELS list defining the accelerometer locations and measurement directions using SAP2000 joint DOFs (notation as described in Description.pdf), (c) complex and real mode shapes in matrix form, and (d) the MAC matrix among the identified modes. The order of channels in CHANNELS matches the column order used in the corresponding accelerometer time series file for that setup.
  • modal_data/acc_Modal_Results_Combined_DBSCAN.txt: combined (multi-setup) modal results obtained by clustering the modes identified in the individual setups. The file reports the consolidated modal frequencies and the setups where each mode was identified. It also provides the assembled real mode-shape matrix expressed in the positive SAP2000 DOF convention; i.e., channel signs are adjusted so that the resulting mode shapes are directly comparable across setups and with the FE mode-shape matrix provided in modal_data/acc_Phi_FEM.txt. The CHANNELS section contains the union of all accelerometer channels used across setups, ordered consistently with the columns of the assembled mode-shape matrix.
  • modal_data/acc_Phi_FEM.txt: FE mode-shape matrix from the SAP2000 model and expressed on the same channel set and positive DOF convention as modal_data/acc_Modal_Results_Combined_DBSCAN.txt.
  • modal_data/sg_modal_results.txt: OMA identification results from the strain-gauge campaign (COV-SSI). The file includes: (a) a summary table with the identified modal frequencies and damping ratios, (b) complex and real mode shapes in matrix form, and (c) the MAC matrix among the identified modes. The mode-shape matrices are reported with one row per strain-gauge channel and one column per identified mode. Channel locations are defined using the SAP2000 frame-element face notation described in Description.pdf (e.g., <FrameObject>.<FrameElement>_<Face>).
  • modal_data/sg_PHI_FEM.txt: FE mode-shape matrix exported from the SAP2000 model at the strain-gauge channels listed under CHANNELS, using the same channel order as sg_modal_results.txt. This enables direct comparison between experimental and numerical strain-based mode shapes (e.g., via MAC).

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