Central Point skyscraper
Central Point is a remarkable building, not only because is one of the highest skyscrapers in Warsaw, but because of its location above the intersection of two subway lines, which was quite challenging during the construction process. DFOS measurement system was of great importance during the construction works. Epsilon Rebars enabled analysis of deformation and settlement of the deep foundation under the bottom of the excavation as well as on deformations in the barrette foundation and foundation slab.
Smart footbridge in Nowy Sącz equipped with EpsilonRebars’s
DFOS sensors in the form of composite rods being simultaneously the structural reinforcement for the concrete deck, were placed along the entire span of nearly 80 m. Thanks to the application of distributed optical fibre sensing technique it was possible to perform measurements of strains, displacements (deflections) and temperature changes in a geometrically continuous manner along the entire length of the footbridge. The sensors integrated with the deck were used to measure selected physical quantities during the hydration of early-age concrete (thermal-shrinkage strains) as well as during the load tests
Prestressed truck scale platforms
EpsilonRebars were used to record strain and temperature changes along several tests during different phases of the platforms lifecycle, starting from hydration process (thermal-shrinkage strains), through tendons activation (strains regarding the transfer of compression forces from the tendons to the concrete) and finally during laboratory tests, when slabs were mechanically loaded in four-point bending test until destruction. Strains and temperatures were recorded every 30 minutes during first day of concrete hydration.
A1 – Smart Highway equipped with integrated self-diagnostic system
SHM System has equipped a pilot section of the road structure being built as part of the A1 highway south of Czestochowa (Poland) with the unique structural health monitoring system. This section with the length of 100 m is reinforced only with the GFRP composite rods, including those integrated with optical fibres for geometrically continuous strain measurements. This means that the applied bars are not only the structural reinforcement, but also integrated sensors providing information about strains and appearing cracks.
57-year-old posttensioned crane girder
This case study presents the results of static and high-frequency strain measurements of a 57-year-old posttensioned crane girder, dismantled from one of the production halls. DFOS system enabled for analysis of anchorage zone and transmission length of the tendon related to the quality of cement injection around the prestressing tendon. The application of Nerve-Sensors allowed for detailed analysis in both longitudinal and transverse directions, including crack detection and estimation of their widths.
In this project one of the most challenging task was to create the concrete "tomograph" and enable strains and temperature measurement in all directions and in many sections of the concrete specimen. Thanks to specially designed version of Nerve-Sensors it was possible to collect thousands of measuring data during first few weeks of concrete hardening without any influence of embedded sensors on concrete behavior. Such experiments and results were not yet described in the literature and are currently being processed in detailed.
Tadeusz Mazowiecki bridge in Rzeszów
In this project we provided Nerve-Sensors for strain, temperature and displacement monitoring of steel suspended bridge in Rzeszów. Sensors were installed at selected girder heights, achieving a total measuring length of 600 m. Measured strains and displacements were mostly result of unregular distribution of temperature over the monitored bridge. The proposed measurement conceptual design of brought great possibilities in the context of assessment of the bridge's technical condition.
CFA concrete columns
This case study presents the analysis of Continuous Flight Auger (CFA) column based on the strain and temperature measurements carried out continuously over the length of 12 m. The measurements were done during the load tests, but also in the early-age concrete, when thermal-shrinkage strains appeared. Obtained data allowed for estimation of integrity and load bearing capacity of the columns, their cooperation with surrounding layered ground as well as calibration of spatial finite element method model and verify theoretical assumptions.
Museum of Modern Art in Warsaw
The construction process of Museum of Modern Art in Warsaw is considered to be one of the most technically complicated and is a big challenge for engineers because of its localization directly above the subway tunnel. One of most important component of the monitoring system was its underground part. EpsilonRebars were used to measure strains during load test of foundation piles. Collected data enabled verification of design assumptions and analysis of cooperation between monitored piles and surrounding ground.
Smart prestressed concrete girders
In this project strain and temperature measurements were performed during the most important stages of construction lifetime, including hydration process (thermal-shrinkage strains), prestressing (tendons activation in order to transfer the compressing force to the concrete), activation of structural dead-weight (as a direct consequence of prestressing phase), installation within the structure (mounting stresses) as well as during the proof load tests. Thanks to the large number of Nerve-Sensors located at selected heights of the girders, detailed analysis of strain profiles was performed during each construction stage.
Slurry wall within R&D projects
Our another example of using Nerve-Sensors are slurry walls, made in technology of fibre-reinforced concrete mixed with the existing ground. This walls were executed within research fields where their behavior was monitored and analyzed by EpsilonRebars during the hydration process, but also during digging the excavation, changing the thermal-moisture conditions, loading the surcharge with concrete slabs and loading the wall directly by the means of hydraulic jackets. Obtained data enabled analysis of strain distributions along slurry wall depth during hardening.
Fibre-reinforced concrete mixed with the ground
Specimens made from the fibre-reinforced concrete mixed with the ground, were equipped with our Nerve-Sensors. Early-age material strains as well as mechanical strains induced in three-point bending tests were measured continuously in geometrical sense and then used for designing the real structural element - slurry wall (presented in another case study).
Optical fibre measurements at PWr (Wrocław University of Technology)
Measurements using distributed optical fibre sensing (DFOS) technique were performed by SHM System in the Faculty of Civil Engineering Laboratory at the Wrocław University of Technology. The results of strain measurements carried out in a geometrically continuous way over designed measurement traces will be used by the PhD students of this Faculty to develop their doctoral dissertations.
3DSensor were installed around the foundation foot, which was then investigated during the pulling out from the ground, i.e. in conditions of extremely large displacements. The uniqueness of this installation is based primarily on the fact that no other measurement technique is able to identify phenomena occurring during the experiment. None of the displacement sensors available on the market could be installed without significant interference into the examined ground, causing the disturbance of the analyzed phenomena and the possibility of its misinterpretation.
The first Polish all-composite FRP bridge
First Polish road bridge fully made of FRP composites is unique not only due to its structural solution, but also thanks to our structural health monitoring based on our DFOS technology. A large number of sensors provide hundreds of measuring points to analyze strain, temperatures and displacements. Learn more about this Nerve-System.
Lightweight concrete specimens
The case study prezents measurements of early-age concrete strains during tests made on the Laboratory of Building Material and Structures at Krakow University of Technology. The specimens under consideration were made from concrete on lightweight sintered aggregate. Some of them were prestressed after achieving the appropriate concrete strength to observe the influence of intensified creep. Our DFOS sensors were installed inside the formwork by specially designed mounting frames.
Concrete cylinder in an axial compression test
The aim of this case study was to provide simultaneous measurements of strains caused by compression (to assess the structural homogeneity of the concrete) and strains caused by tension (allowing for the identification of cracks perpendicular to the measuring line). Obtained data enabled to identify local strain extremes at an early stage of loading, especially when the concrete is not cracked or when microcracks are invisible to the naked eye and do not yet significantly affect the structural behavior.
The worldwide unique solution was the application of the smart EpsilonRebar sensors (DFOS technology) with a length of 17 m each to control the behaviour of the foundation piles. Thanks to the measurements carried out geometrically continuous along the entire length of the sensors, it is possible to analyze the force distribution transferred to the foundation during the erection of subsequent floors of the skyscraper. The EpsilonRebar sensors allow also for identification of the weakest cross-sections and the appeared cracks. Four fibre optic sensors installed within the Skyliner site provide data corresponding to 13,600 traditional spot strain gauges.