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Structural identification of masonry arch bridges
No full textMasonry bridges play a crucial role mainly in the European rail and road network but also in other countries, such as Japan and India, they can are among the most important infrastructures of the transportation systems. Thus, a rational approach is needed for their assessment which reliability is strictly related to the structural models and to the constitutive models, and related mechanical parameters, used for the materials. How reliability can be achieved and corroborated is still an open issue.
In this paper, procedures for both material and bridge testing are discussed aiming at a general procedure for the identification of the mechanical properties of materials and of the structure.
Two case studies are presented and discussed: the Tanaro Bridge in Italy and the Rakanji Bridge in Japan. Data from material testing are used to set up FEM models; dynamic tests on the bridges are then used to corroborate the reliability of the structural model. In the case of the Rakanji Bridge, the numerical model has been also updated on the base of the experimental dynamic response
Smart reinforcement steel bars embedded with MEMS sensors for low-cost structural health monitoring
No full textTanaro Bridge: Dynamic Tests on a Couple of Spans
No full textThe Tanaro Bridge, an 18span 225m long bridge on the Tanaro river in north-western Italy, presented elements of interest: i) the barrel divided into adjacent arches; ii) transverse tie bars and internal spandrels connecting the three parts of the barrels. Its demolition, in 2003, gave the opportunity of performing dynamic tests on a couple of spans at two stages of demolition: i) fill removed; ii) fill and internal spandrels removed. Without the uncertain contribution of the fill, some features of the mechanical response of masonry bridges is discussed and the efficiency of tie bars and internal spandrels is addressed. The data provided can be useful for safety assessment procedure
Experimental identification of a multi-spanmasonry bridge: The Tanaro Bridge
No full textThe Tanaro Bridge, an 18 span masonry bridge built in 1866, has been investigated both in service conditions and at different stages of its demolition. A comparative characterization of the brickwork was performed by means of compressive tests on cylinders, flat jacks, sonic and sclerometer tests, while the natural frequencies and mode shapes of the bridge and the brickwork damping have been identified by dynamic tests on the bridge. Data from material testing were used to set up FEM models, so that the reliability of the material characterization procedures is demonstrated by comparison between the dynamic tests and FEM results. A rational comparative analysis of the results showed that: (i) a large part of the bridge needs to be monitored if the mode shapes are to be identified through dynamic tests; (ii) elastic FEM models can provide some information on the bridge response under service loads provided the mechanical parameters are adequately identified. Besides, some information has been deduced on the effectiveness, in service conditions, of some retrofitting technique: (i) transversal tie bars through the arch thickness have been proved almost ineffective; (ii) internal spandrels were found to be quite efficient in connecting adjacent span
Experimental evaluation of the effect of controlled damages on the dynamic response of PC bridge beams
Full text linkThe present paper describes the dynamic test campaign on the prestressed concrete bridge beams taken from a dismantled viaduct in Turin, Italy after a service life of 50 years in the framework of BRIDGE|50 research project. Dynamic measurements were previously performed on the decks from which the 29 beams were taken to characterize the behaviour of the viaduct in service condition. Successively the single beams are tested to evaluate the effects of the different damage levels on the dynamic properties. The vibration data have been collected before the application of static load, after the first cracking condition and after the maximum load capacity of the beam and analysed to extract the principal modal components. The results highlight the correlation among the evolution of the damage and the dynamic response of the beam and then the effectiveness of vibration tests to identify the occurrence of damages and follow their evolution. The experimental findings will be used in future works to explore the effects of damages of the single beams on the global response of this bridge typology. This work presents the results of the experimental tests on the first three beams
Smart reinforcement steel bars embedded with low-cost MEMS sensors for strain monitoring
No full textExperimental test on an RC beam equipped with embedded barometric pressure sensors for strains measurement
Full text linkThe current trend in structural health monitoring (SHM) is to install increasingly large numbers of distributed, heterogeneous types of sensors, for a timely and exhaustive detection of any possible damage scenario evolving in the system. These sensors should be low-cost, easy to install, robust and durable. Among others, strain remains one of the most straightforward measurands for monitoring the state of a structural element and for assessing its health condition. However, for application to reinforced concrete structures, currently available strain sensing devices, such as electric strain gauges or fibre optic sensors, do not fully satisfy the aforementioned requirements, generally proving difficult to install, fragile and expensive. In this paper, an innovative monitoring technology, called Smart Steel System (S3), is proposed that measures strains in reinforced concrete members, by incorporating commercial barometric pressure MEMS sensors in appropriate sealed cavities embedded in the reinforcing steel bars. The results of an experimental campaign are reported, in which a reinforced concrete beam, instrumented with both S3 devices and conventional electrical strain gauges, is subjected to increasing loading and unloading cycles until collapse. The tests show the superior robustness of the S3 system during construction and loading as well as its good sensing accuracy, demonstrating its potential for a massive use in SHM applications
Erratum: Dynamic behavior of shallow founded historic towers: Validation of simplified approaches for seismic analyses (International Journal of Geotechnical Engineering 9:1 (13-29) DOI: 10.1179/1939787914Y.0000000066)
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