Abstract

The paper presents the overall objectives of a funded research program for the development of a Conservation Plan (CP) for the two halls by Pier Luigi Nervi of the Turin Exhibition Center. The Turin Exhibition Center was conceived immediately after the Second World War to host primarily the annual Automobile Show, in connection with the presence in Turin of the FIAT motor company. The two main pavilions of the Center (Halls B and C) are outstanding examples of a pioneering use, of new advanced methods in reinforced concrete construction, combining innovative prefabrication procedures and the re-invention by Nervi of ferrocement, used to form extremely thin elements. The CP is expected to push and contribute to the preservation of the halls designed and built by Nervi, with special emphasis on structural and seismic vulnerability aspects, also due to concerns raised on the durability of concrete materials and technologies. Re-using these buildings entails the challenge to guarantee new extended service life to concrete structures built many decades ago and faces the need for a seismic assessment of these structures, in compliance to recent Italian standards.

Abstract

Present work summarizes a study on the stability of some parts of the Claudius Aqueduct in Rome (1st century AD). The project provides empirical applications linked to the definition of minimal interventions for the structural restoration of a section of the structure near Capannelle. Results of the kinematic analyzes conducted and of experiment with a physical model representing the structure of the upper hydraulic conduit (speco) are reported. Ultimately, hypothetical minimal interventions are outlined for the protection of the structure and at the same time of the image and usability of the Aqueduct.

Abstract

This paper aims to present, via a case study, an interdisciplinary approach towards the comprehensive analysis of historic constructions. The case study monument examined is the Medieval Manor of Potamia in Cyprus. The work hereby presented was based on a collaboration between scientists from the fields of archeology, architecture, materials science/ conservation and structural engineering. A thorough review of historical sources was initially carried out in order to obtain data concerning the history and construction development of the Manor. Extensive field work was undertaken to study the architectural typology and construction detailing of the structures and to explicitly map the various agents of pathology. For the characterization of the historic fabric, masonry materials were sampled and studied at the laboratory. The accumulated data facilitated the development of a Finite Element (FE) model, which was used to numerically assess the structure’s seismic response.

Abstract

Dynamic monitoring is a well-established technique used to gain information on the global health of constructions. In particular, ambient vibration tests have achieved important results in the dynamic characterization of modal parameters. Several techniques and instrumentations are currently available, however the accuracy of these results is often unquestioned. The mutual validation between different modal analysis techniques is an important procedure to assess the reliability of the results. In the present paper the ambient vibration tests performed on the so-called ‘Temple of Minerva Medica’ in Rome considering different techniques and instrumentations will be described and compared. While it is referred to as the Temple of Minerva Medica, the structure is actually a ruined decagonal nymphaeum in opus latericium that dates to the 4th century AD. Today, the construction is located between the main central train station (Roma Termini) and the local tram way. Ambient vibration data were acquired during different campaigns [1] to characterize the effects of the vibrations and the modal parameters of the structure. This work deals with the data collected on the 11th of July 2019 within the project “Tecnologie per il miglioramento della Sicurezza e la ricostruzione dei centri Storici in area sismica” coordinated by DTC Lazio (Distretto Tecnologico beni e attività culturali). The instrumentation comprised of several seismographs equipped with triaxial velocimeters and piezoelectric accelerometers. A variety of techniques were applied to process the acquired vibration data in order to extract the modal parameters of the studied structure including PolyMAX, FDD, EFDD, CC-SSI, HVSR and FRF. Comparison of the modal parameters obtained by each different technique was considered to provide indications on the reliability of the instruments.

Abstract

Reinforced concrete was introduced by patented systems into Spain towards the end of the 19th c. Early patents were effectively foreign trademarks, although Spanish engineers, architects and industrialists soon developed their own RC systems. Local builders would build structures with scarce little regard for calculated design and construction in the first decade of the 20th century. Nevertheless, as further knowledge was required, increasing research led to new RC standards in numerous countries, such as France and Germany. In the second decade of the 20th century, the use of patent systems declined. The teaching of RC started at the Spanish Civil Faculty where systems of scientific calculation were rapidly adopted, although no Spanish RC standard was drafted, unlike the situation in the leading European countries of that time. Hence, the RC structures that proliferated across Spain were mainly based on French or German standards. Spanish industrial activity began to develop in northern areas of the country where the use of new materials was pioneered over the following decades. Nowadays, some of those structures are listed heritage buildings. In this paper, some common features of 15 RC structures built between 1915 and 1936 are discussed, by focusing on their conservation problems. Preliminary structural reports from engineers, architects, municipal councils and, in some cases, the owners of the buildings are compiled with information on the pathologies affecting the buildings and analyses of structural morphologies, and steel and concrete strengths. The results of those studies are analysed, by connecting construction features with structural conditions, in order to gain a deeper understanding of their main characteristics and similarities. The findings will contribute to knowledge of heritage buildings, identifying key strategies for application in future rehabilitation works.

Abstract

The present study case highlights the importance of considering local failures for irregular unreinforced masonry buildings, by means of nonlinear seismic analyses. Simplified seismic assessments based on equivalent frame method were used in order to capture the structural behavior of the National Geological Museum from Bucharest in its initial form and also the current structural layout. The retrofitting works realized in the 1982 were focused on strengthening the transversal masonry walls and on creating horizontal diaphragms to improve the “box behavior” of the building subjected to lateral forces. Retrofitting of unreinforced masonry walls by reinforced concrete jacketing and the replacement of flexible floors by reinforced concrete slabs were previously considered to be effective only though post-earthquake visual inspections of the strengthened elements. The efficiency of past interventions is studied in the present paper through comparisons between the two models in terms of damage patterns, global behavior and also performance levels established function of maximum relative displacements.

Abstract

The introduction of reinforced concrete as a structural material in American practice circa 1900 created unique challenges in design and analysis. Engineers and builders had to simultaneously determine proper constituent materials for the concrete, the relation between materials proportions and strength, and formulas for sharing load between steel and concrete. Early on there were only local building codes, which often treated concrete as masonry. This was followed, starting in 1909, by the reports of the “Joint Committee” which served as a de facto national code for concrete; the American Concrete Institute code was first independently published in 1941 and has been updated regularly since. All of the early codes, specifically including the Joint Committee report and the ACI code, used allowable-stress design with a linear-elastic model of flexure. Load-and-resistance factor design using an ultimate-strength model was first introduced in the US as an alternate method in the 1956 ACI code, was elevated to equal status with the 1963 code, and was made the standard in the 1971 code with the linear-elastic allowable-stress model as an alternate. Since the ultimate-strength model is generally accepted to more accurately represent flexure in reinforced concrete, the allowable-stress alternate was little used after the transition. Many details have changed minimally since the 1910s, including provisions for T beams that take advantage of the slab for additional compression flange area. The calculation of shear capacity in both concrete and web reinforcing changed minimally except for the transition from allowable-stress to load-and-resistance-factor design. Re-analysis of extant concrete structures designed before the 1956 code generally shows a pattern of significant excess capacity in flexure and limited excess capacity in shear. For members that are generally not controlled by one-way (beam) shear (two-way slabs and one- way slabs) the increase in flexure capacity governs; for members where one-way shear is a controlling factor, the small increase, no change, or decrease in shear capacity governs. Much of the current literature on evaluating the capacity of extant concrete structures focusses on strength degradation from material changes such as rusting rebar and from overall material changes such as carbonation. The presence of excess capacity should also be considered, and it is possible based on review of the governing codes and design methods to determine general patterns as to how much excess capacity may be expected.

Abstract

The international cultural and historical heritage is often subject to degradation and damage. The main causes contributing to these phenomena are the chemical and mechanical actions due to acid rain, environmental pollution, and earthquakes. Other causes are the cycles of freezing and thawing that induce the manifestation of internal stresses leading to the deterioration of the material and the collapse of structural parts. In the field of architectural restoration, this problem has been addressed by two main solutions. The first involves cleaning processes that leave the missing parts visible; the second consists of introducing reproductions of the missing parts, creating a clear distinction between pre-existing and new elements. In both cases, the seismic behavior of the structure is modified; in the second solution, the added elements do not contribute to the structural strength since they are made of plaster or stucco. This work aims at presenting a preliminary study on the creation of replacements of missing elements within damaged heritage buildings. The work is structured in two distinct phases. In the first phase, specific cubic specimens, created with a 3D printer, are produced and subjected to uniaxial compression tests. The experimental campaign is carried out in order to provide useful information regarding the 3D material engineering constants that are currently absent in the literature. In the second phase, the experimental results are used in a numerical model to calibrate the mechanical properties of an equivalent homogeneous material.

Abstract

The bridge over the Quisi Ravine in Alicante Province (Spain), built between 1913 and 1915, consists of six 22-22-42-42-22-22 m long steel Pratt truss spans, the lateral spans being isostatic and the central spans continuous. All the joints between the steel elements are riveted. As the bridge has been carrying railway traffic for more than 100 years, its condition needed to be assessed before carrying out the necessary repairs reinforcement to extend its service life. One of the most interesting tasks on the bridge involved a study of its fatigue behaviour to estimate its remaining useful life. Only a few kilometres away there happened to be another bridge with identical geometry over the Ferrandet Ravine, which had recently been dismantled and taken out of service and had carried the same railway traffic as the one over the Quisi Ravine. Advantage was therefore taken of this unique opportunity to test one of its isostatic spans in order to extrapolate the results to the Quisi Bridge. These tests were carried out at the ICITECH laboratories at the Universitat Politècnica de València in two different scenarios: 1) one test on a 22 m span, and 2) another on one of its girders, in both of which simulated railway traffic cyclical loads were applied. The results allowed us to estimate the number of trains that could pass over the bridge and its remaining service life, and also to define a monitoring method to help in decision making in case of possible failures of its component parts. The study also included an analysis of the bridge’s robustness in local failures of some of its elements, which led to a further bridge cyclical loading test with a deliberately damaged component. Even though other researchers had previously carried out fatigue tests on full-scale riveted bridge elements, the ICITECH study is unique in that it is the first time a full-scale bridge has been subjected to fatigue tests. This work was accompanied by advanced numerical modelling studies considering the fracture mechanics theory.