PSI - Issue 13

Vera Vujović / Procedia Structural Integrity 13 (2018) 1901 – 1907 Vera Vujovi ć / Structural Integrity Procedia 00 (2018) 000–000

1905

5

4. Bridge monitoring and equipment 4.1. Main bridge construction design

The monitoring system embedded in the construction of the bridge had the role of ensuring, as a traffic safety measure, continuous and stationary control of the behavior of the bridge pillars over a longer period of time during the exploitation of the bridge. The pillars of the bridge are extremely high, and the terrain of the Mala Rijeka valley where the pillars are funded is very steep. The initial observation envisaged measurement of the sizes: horizontal displacements of the columns 2-5; vertical displacement of columns 2-5; rotation of the basement; changing the width of existing cracks on column no.3; horizontal displacement of the rapper on the wall near the columns; vertical movements on the wall near the pillars; moving the walls along certain directions.

Table 3. Special equipment

Special equipment

Description

revision trolley movable scaffolding with a basic control mechanism for inspection and examination of the bridge construction

coordinate plumb-bob slitometers

at center of columns 3 and 4 (measurements of relative horizontal displacement of columns);

within the monitoring of the wall mass near the columns no. 3 and no. 4, a special design of measurement envisaged observation of the relative horizontal shift of the foundations and pillars in relation to the level of approximately 30 m in the depth of the wall. Slitometer operates on the principle of reverse (inverse viscous clinometer is a measuring instrument used to precisely measure angular tilt changes, based on a highly sensitive spike whose movements are controlled using a micrometer screw measuring device for determining the distance between two points by comparison of the state before and after the change. measurement determines the change of the initial distance (measurement base), which is most often expressed in the engineering application as relative displacement in percentages or as a linear deformation of a small order of magnitude. extensometers can be contactless (for example, optical, laser triangulation or interferometric, sonar) or contact (for example, mechanical). they are most often an integral part of a measuring system made up of one or more measuring devices, as well as a central unit for automatic recording and processing of results. they are applied when monitoring changes in the earth's crust (eg, deformations in areas of high seismic activity), monitoring of large structures (eg deformation or swaying of bridges), determination of mechanical properties of materials, etc. measuring instrument for measuring wind speed and air flow rate the role of an anemometer is measuring several or all of the components of the wind vector. the ideal measured wind sensor responds to the smallest breeze and wind like a hurricane, has a linear outlet and currently reacts to turbulent fluctuations a few anemometers with blades were installed on the bridge 4.2. Main design of bridge rehabilitation - Structural Health Monitoring SHM Contemporary structural health monitoring (SHM) is a process that aims to provide accurate and timely information related to the state of integrity of structures and characteristics that can serve as the basis for making a decision for operation, maintenance and corrections. The main steps of SHM are: a choice of monitoring strategy; installation and maintenance of equipment for monitoring and data management. The monitoring strategy consists of: defining the objectives of monitoring; selection of parameters; the choice of monitoring system; defining a network of sensors and a dynamic monitoring plan. The basic elements of the monitoring system are: sensors; reading units and driver software, cables, connecting boxes, etc. The basic requirements that the bridge must fulfill are: safety, usability and durability. Bridge SHM is based on the data collection that determines the behaviour of the bridge in accordance with the design requirements. It is assumed that a certain number of sensors are placed in the grid nodes, the strain gauge sensors in the grid rods, and the bearings (the setting of the sensor on the concrete parts of the high pillars is not considered). The monitoring system with remote control and the assumption based on the market price of the system for one sensor of 540 euros was considered, the tendency towards massive application and the optimization of the number of sensors by the SHM experts would enable the reduction of the costs for the development of this system. Along the Belgrade-Bar line, implemented project that has been installation a multifunctional optical fibre cable, so that future study analysis by the experts will enable the assessment of the possibility of possible linking of the SHM, which, if feasible, would allow further reduction of the preliminary rough estimate costs from this paper. clinometers extensometers anemometer signaling system switched off after installation of protective barrier