Sustainability is a pressing concern of the 21st century. Social development in most countries is raising awareness of the needs of future generations and legislation to protect the present and future quality of life. These needs are compelling various sectors, including construction, to find sustainable solutions. This paper investigates the feasibility of incorporating high-quality recycled concrete aggregates in new concrete, providing a recycling option for precast rejects. The massification of recycled aggregate incorporation would decrease the environmental impacts of the concrete industry, for instance due to reduced landfill disposals, less quarry mining and shortened transport distances. The study presented in this paper concerns the material, mechanical, durability and short-term structural behaviour of concrete specimens and structures made with recycled aggregates sourced from high-quality concrete elements. This paper intends to provide a holistic view of the study, from the procurement and crushing process that generated the aggregates to the conclusions of the different experiments performed. The results of this experimental campaign are benchmarked with other investigations and the importance of the quality of the RA is evaluated. This paper concerns the first full-scale experiments made on recycled aggregates concrete structures. Also, some of the tests performed were the first of their type made on recycled aggregates concrete.

Structural, material, mechanical and durability properties and behaviour of recycled aggregates concrete

Environmental effects on natural frequencies of the San Pietro bell tower in Perugia, Italy, and their removal for structural performance assessment

This article presents the development and the results of 1 year of implementation of a simple vibration-based structural health monitoring system for preventive conservation and condition-based mai...

Vibration-based structural health monitoring of a historic bell-tower using output-only measurements and multivariate statistical analysis

The response of the San Pietro monumental bell-tower located in Perugia, Italy, to the 2016 Central Italy seismic sequence is investigated, taking advantage of the availability of field data recorded by a vibration-based SHM system installed in December 2014 to detect earthquake-induced damages. The tower is located about 85 km in the NW direction from the epicenter of the first major shock of the sequence, the Accumoli Mw6.0 earthquake of August 24th, resulting in a small local PGA of about 30 cm/s2, whereby near-field PGA was measured as 915.97 cm/s2 (E–W component) and 445.59 cm/s2 (N–S component). Similar PGA values also characterized the two other major shocks of the sequence (Ussita Mw5.9 and Norcia Mw6.5 earthquakes of October 26th and 30th, respectively). Despite the relatively low intensity of such earthquakes in Perugia, the analysis of long-term monitoring data clearly highlights that small permanent changes in the structural behavior of the bell-tower have occurred after the earthquakes, with decreases in all identified natural frequencies. Such natural frequency decays are fully consistent with what predicted by non-linear finite element simulations and, in particular, with the development of microcracks at the base of the columns of the belfry. Microcracks in these regions, and in the rest of tower, are however hardly distinguishable from pre-existing ones and from the physiological cracking of a masonry structure, what validates the effectiveness of the SHM system in detecting earthquake-induced damage at a stage where this is not yet detectable by visual inspections.

Assessment of a monumental masonry bell-tower after 2016 Central Italy seismic sequence by long-term SHM

From continuous vibration monitoring to FEM-based damage assessment: Application on a stone-masonry tower

The results of an ambient-vibration based investigation conducted on a historical tower in Italy, to update the 3-D finite element model of the building are presented in this work. The main difficulties are related to the extreme in-homogeneity of the building and the presence of an elevator vain that occupies the posterior part of the tower, forcing to locate the accelerometers only on one facade of the building. The assessment procedure include full-scale ambient vibration testing, modal identification from ambient vibration responses using three different identification methods, finite element modeling and dynamic-based identification of the uncertain structural parameters of the model. A very good match between theoretical and experimental modal parameters was reached and the model updating has been performed to identify some structural parameters.

Ambient vibration testing, dynamic identification and model updating of a historic tower

In this paper, the latest identification techniques both in the time and in the frequency domains, are applied to the data obtained from the dynamic monitoring of the reinforced concrete tower of the Provincial Administration Building of Bari (Italy). The tower, dating back to the thirties of the 20th century and about 60 m tall, is not only a typical example of the fascist architectural style, but it is an important symbol of the city itself. The extraction of the modal parameters from ambient vibration data has been carried out by using the ARTeMIS Extractor Pro 2010 software. Three different Operational Modal Analysis (OMA) methods have been utilized: EFDD, SSI and Crystal Clear-SSI. The first two couples of bending mode shapes are also estimated and shown.

Michele Mongelli

Papers

Ambient vibration testing, dynamic identification and model updating of a historic tower

Operational Modal Analysis of a Historic Tower in Bari

Dynamic behavior of a Historic Tower in Bari