Ramón Irles

Image processing for safety assessment in civil engineering

Behavior analysis of construction safety systems is of fundamental importance to avoid accidental injuries. Traditionally, measurements of dynamic actions in civil engineering have been done through accelerometers, but high-speed cameras and image processing techniques can play an important role in this area. Here, we propose using morphological image filtering and Hough transform on high-speed video sequence as tools for dynamic measurements on that field. The presented method is applied to obtain the trajectory and acceleration of a cylindrical ballast falling from a building and trapped by a thread net. Results show that safety recommendations given in construction codes can be potentially dangerous for workers.

Acceleration and Deflection Analysis for Class C Edge Protection Systems in Construction Work

B. Ferrer acknowledges the support of the Generalitat Valenciana through the project GV/2013/009 and the Spanish Ministerio de Economia y Competitividad through the project BIA2011-22704.

High speed image techniques for construction safety net monitoring in outdoor conditions

The behaviour of a construction safety net and its supporting structure was monitored with a high speed camera and image processing techniques. A 75 kg cylinder was used to simulate a falling human body from a higher location in a sloped surface of a building under construction. The cylinder rolled down over a ramp until it reaches the net. The behaviour of the net and its supporting structure was analysed through the movement of the cylinder once it reaches the net. The impact was captured from a lateral side with a high speed camera working at 512 frames per second. In order to obtain the cylinder position each frame of the sequence was binarized. Through morphological image processing the contour of the cylinder was isolated from the background and with a Hough transform the presence of the circle was detected. With this, forces and accelerations applying on the net and the supporting structure have been described, together with the trajectory of the cylinder. All the experiment has been done in a real structure in outdoors location. Difficulties found in the preparation on the experiment and in extracting the final cylinder contour are described and some recommendations are giving for future implementations.

Low-speed vehicle impact against building structures: a review of relevant codes

The new building codes tend to include vehicle impacts as part of the accidental actions to be considered. Most of these codes use equivalent static load to represent the effects of the impact against the structure. In this paper a bibliographical review of the indications is performed as provided by some of the most representative buildings codes in the world relating to impacts caused by vehicles. In particular we will focus on impacts caused by horizontal actions on structures, like car crashes against parking columns. We will show that the indications provided by the different standards studied are widely different each other and that there is not a clearly agreed procedure allowing the assessment of the effects of a vehicle impact through an equivalent static load. Keywords: Building codes & standards, impact, car parks, equivalent static load.

Sistemas de protección individual anticaídas sometidos a impacto. Simulaciones numéricas

Personal fall protection systems are set up by EN-363 to avoid or retain people falls safely (without relevant damages). They are the ultimate resource to prevent a fall after other measures being considered. This paper analyses the variables affecting the system behaviour: free fall height, length of retaining rope, stiffness and damping of retaining material, and worker weight. To this end, fall phenomenon has been simulated with finite elements dynamic models with an elas- tic rope and a rigid ballast. It allows obtain likely values of maximum forces on the injured and over the system during the impact. Results demonstrate the fundamental role of height fall vs. rope length rate (fall factor), which results more important than the fall height itself. The severe values obtained for maximum forces show that future research would include elastoplastic energy absorbers to decrease impact until reasonable values.