Engineering Structures 27 (2005) 1859–1864 www.elsevier.com/locate/engstruct Displacements measurement in a building model using the speckle photography technique Rolando González-Peña a , Rosa M. Cibrián Ortiz de Anda b,∗ , Angel J. Pino-Velázquez c , José Soler-de la Cruz c , Carlos Llanes Burón c , Rosario Salvador Palmer b , Mateo Buendía Gómez b a Physics Department, High Polytechnics Institute “José Antonio Echeverría”, CP 19390, Havana, Cuba b Faculty of Medicine and Odontology, Department of Physiology, Biophysics and Medical Physics Unit, University of Valencia, Avda. Blasco Ibáñez 15, 46010, Valencia, Spain c Civil Engineering Faculty, High Polytechnics Institute “José Antonio Echeverría”, CP 19390, Havana, Cuba Received 7 October 2004; received in revised form 13 June 2005; accepted 13 June 2005 Available online 10 August 2005 Abstract The use of reduced scale models in civil engineering has made it possible to study large structures such as buildings. Using non-destructive optical techniques such as double-exposure speckle photography, extremely valuable results can be obtained, where mathematical methods are often not very exact. This work studies the model of an eighteen-storey building in which displacements can be measured at each storey of each view. It also presents a comparison of the displacement field, which was obtained with the Finite Element Method. © 2005 Elsevier Ltd. All rights reserved. Keywords: Speckle photography; Building model; Shear walls 1. Introduction The measurement of deformations under loading condi- tions is usually obtained in mechanical tests by means of strain gauges glued directly to the specimen, or by displace- ment transducers connected to points of interest. However, these approaches present some drawbacks: both methods provide values averaged over the evaluated area only and it is often unclear whether or not they affect the measurement [1]. For this reason non-destructive testing (NDT) techniques are increasingly used for strain–stress characterisation of struc- tural elements. Double-exposure speckle photography is a well-establi- shed whole-field technique for measuring in-plane displace- ment, vibration and the tilt of diffusely reflecting surfaces. A major advantage of this method is the relative simplicity ∗ Corresponding author. Tel.: +34 96 3864157; fax: +34 96 3864537. E-mail address: Rosa.M.Cibrian@uv.es (R.M. Cibrián Ortiz de Anda). 0141-0296/$ - see front matter © 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.engstruct.2005.06.009 of the experimental set-up [2–5]. It has been applied successfully to study structural elements [6,7] and to mea- sure deformation in buildings in situ [8,9]. Some optical tests, however, due to experimental limitations, cannot be applied directly to real structures because of the large dimensions sometimes involved; consequently the use of reduced scale models becomes necessary. A reduced scale model, when the analogy with the real building is correct, makes it possible to see the actual behaviour of the model and to determine experimentally the error in the measure- ments when certain types of loads are applied. Thus, when the results are extrapolated to the real building, the expected uncertainty can be calculated. In mathematical methods, like the finite element method (FEM), the study is also carried out on a model that approximately reproduces the actual behaviour of the structure. The degree of exactitude becomes greater when the following conditions are fulfilled: when the element type selected is the most suited to simulate the real object; the mesh is finer; the elastic characteristics of the