BLAST Simulator Project: Performance assessment and preliminary tests. Administrative Arrangement No JRC 32253-2011 with DG HOME Activity A5 – Blast Simulation Technology Development

The Blast Simulator project involves the development of an apparatus able to reproduce the effects of a blast pressure wave on large scale structural components (such as columns, walls, etc.) with the objective to improve their strength in these severe loading situations. This technical report presents the setting up and the performance assessment of the prototype blast actuator developed at the JRC. The first preliminary tests performed have been described and evaluated. Satisfactory results have been obtained with respect to impacting masses and velocities and with the finally obtained pressure values.JRC.G.5-European laboratory for structural assessmen

Calibration procedure for force and displacement measurements at the HOPLAB

The report explains the calibration procedure of the HOPLAB facility. A short description of the facility is first included concerning the mechanical structure and its equipment in terms of sensors, transducers and relevant electronic instruments. A detailed explanation of the calibration procedure is next presented, which is principally centered at calibrating the force measurements along the input and output bars with a certified load cell. The main issues and problems connected to this particular testing rig are discussed. Finally an example of a typical elaboration, starting from raw experimental data to obtain the force-displacement curve of a specimen in tension, is provided.JRC.G.5-European laboratory for structural assessmen

Procedure for load cell calibration at ELSA Reaction Wall

This report describes the procedure currently applied for the calibration of the load cells used for the mechanical experiments in the ELSA laboratory. The procedure is based on the international norm ISO 7500-1 and the definitions there proposed. The calibration experiment consists of applying a number of load cycles simultaneously on the object load cell in series with a traceable measuring proving instrument externally calibrated (reference load cell). The accuracy of the measures of the object load cell is the most important result of the test delimiting the maximum difference between both instruments. Other important results of the test are the resolution, repeatability and reversibility of the object load cell. All these error parameters determine the quality of the object instrument at the state of the calibration test. In order to extend the validity of the calibration test to the experiments performed with that load cell when connected to amplifiers different from the one of the calibration test, an additional gain test of the signal conditioning chain is also undertaken at ELSA after the calibration test.JRC.G.5-European laboratory for structural assessmen

Blast Simulator project: First tests on reinforced concrete beams

The Blast Simulator project involves the development of an apparatus able to reproduce the effects of a blast pressure wave on large scale structural components (such as columns, walls, etc.) with the objective to improve their strength in these severe loading situations. After a series of preliminary tests to assess the performance of the blast actuator for what concerns the energy capability, this technical report presents some results related to a test campaign on two full scale structural components, specifically tworeinforced concrete beams.. With appropriate improvements made to the impactor, it has been possible to successfully bring the components to failure. A full suite of test parameters has also been recorded, valuable for guiding the numerical modelling. These experiments validate the potentiality of this kind of equipment to reproduce in a laboratory the effects of a blast explosion on full scale structural elements without using explosives. Further tests with the same experimental setup and with a new testing rig based on a more innovative technology (electrical linear motor) will be conducted in 2015 in the context of BUILTCIP project.JRC.G.4-European laboratory for structural assessmen

Large scale high strain-rate tests of concrete

This work presents the stages of development of some innovative equipment, based on Hopkinson bar techniques, for performing large scale dynamic tests of concrete specimens. The activity is centered at the recently upgraded HOPLAB facility, which is basically a split Hopkinson bar with a total length of approximately 200m and with bar diameters of 72 mm. Through pre-tensioning and suddenly releasing a steel cable, force pulses of up to 2 MN, 250 μs rise time and 40 ms duration can be generated and applied to the specimen tested. The dynamic compression loading has first been treated and several modifications in the basic configuration have been introduced. Twin incident and transmitter bars have been installed with strong steel plates at their ends where large specimens can be accommodated. A series of calibration and qualification tests has been conducted and the first real tests on concrete cylindrical specimens of 20cm diameter and up to 40cm length have commenced. Preliminary results from the analysis of the recorded signals indicate proper Hopkinson bar testing conditions and reliable functioning of the facility.JRC.G.5-European laboratory for structural assessmen

Strain Rate Effects in Nuclear Steels at Room and Higher Temperatures.

Abstract not availableJRC.G-Institute for the Protection and the Security of the Citizen (Ispra

Stability and accuracy in a hybrid test example

This paper presents an example of the application of error monitoring techniques to the results of a pseudodynamic test performed at variable testing speeds. For the faster testing speeds, the control errors increased and the test reliability was lost in terms of accuracy and stability, as observed by the evolution of the monitoring parameters. The applied monitoring methods were the spatial model identification of frequency and damping distortions and the error energy, which have been proposed in previous publications.JRC.G.5-European laboratory for structural assessmen

Mixed-Variable Control for Shear Tests on Massive Reinforced-Concrete Walls

Within the frame of the European project IRIS, five reinforced concrete walls have been tested in shear at the ELSA. The thickness of the wall was exceptionally large (40cm) for this kind of test. The testing setup was able to apply quasistatically a shear force of up to 12 MN by means of four horizontal actuators and the vertical load and rotations were controlled by another four smaller actuators. The applied mixed-variable control at the horizontal actuators, with feedback based on a combination of force and displacement, allowed to have a smooth response of the system also in the situations of collapse of the specimen or at the central gap zone in which the horizontal pistons where not in contact with the loading system. In addition to this control, a low-speed regulator algorithm running in MATLAB closed an external loop that managed the variation of the target to the controllers in order to perform the required loops at the specified force or displacement level. This sophisticated setup and control, plus the conventional instrumentation combined to high-resolution photogrammetry, have allowed to perform the tests with a high accuracy in the quantity and uniformity of the load and high quality in the measurements.JRC.G.5-European laboratory for structural assessmen

Experimental assessment of a three storey full-scale precast structure. SAFECAST Project: Work Package 4, Technical Report

In the framework of the SAFECAST Project, a full-scale three-storey precast building was subjected to a series of pseudodynamic (PsD) tests in the European Laboratory for Structural Assessment (ELSA) at the Joint Research Centre of the European Commission. The mock-up was constructed in such a way that four different structural configurations could be investigated experimentally. Therefore, the behaviour of various parameters like the types of mechanical connections (traditional as well as innovative) and the presence or absence of shear walls along with the framed structure were investigated. The first PsD tests were conducted on a dual frame-wall precast system, where two precast shear wall units were connected to the mock up. The first test structure sustained the maximum earthquake for which it had been designed with small horizontal deformations. In the second layout, the shear walls were disconnected from the structure, to test the building in its most typical configuration, namely with hinged beam-column connections by means of dowel bars (shear connectors). This configuration was quite flexible and suffered large deformations under the design level earthquake. An innovative connection system, embedded in the precast elements, was then activated to create emulative beam-column connections in the last two structural configurations. In particular, in the third layout the connectors were restrained only at the top floor, whereas in the fourth layout the connection system was activated in all beam-column joints. The PsD test results showed that, when activated at all the floors, the proposed connection system is quite effective as a means of implementing dry precast (quasi) emulative moment-resisting frames.JRC.G.5-European laboratory for structural assessmen

Seismic Tests on Reinforced Concrete and Steel Frames Retrofitted with Dissipative Braces

Seismic tests have been conducted on two 3-storey structures protected with pressurized fluid-viscous spring damper devices. One of the structures was a reinforced concrete frame with clay elements in the slabs, while the other one was a steel frame with steel/concrete composite slabs. The spring dampers were installed through K bracing in between the floors. The tests were performed by means of the pseudodynamic method, which allowed the use of large and full-size specimens, and by implementing a specific compensation strategy for the strain-rate effect at the devices. The test results allowed to verify the adequacy of the attachment system as well as to compare the behaviour of the unprotected buildings with several protected configurations, showing the benefits of the application of the devices and the characteristics of their performance. The response of the protected structures was always safer than that of the unprotected ones mainly due to a significant increase of equivalent damping. The increase in the damping ratio depends on the level of deformation.JRC.G.5-European laboratory for structural assessmen