Scipedia: 12th International Conference on Structural Analysis of Historical Constructions (SAHC)

An Innovative Shell Structure in Codogno (Italy). Evaluation of Structural and Seismic Performance

Scipedia content — Tue, 30 Nov 2021 12:51:48 +0100

The saddle-shaped shells, or hyperbolic paraboloids, often joined together to form a pitched roof or an inverted umbrella, were used by many pioneers in structural architecture, such as Félix Candela, which introduced a very innovative use of reinforced concrete in thin layers or together with some reticulated ribs. An innovative semi-prefabricated building system was developed in Italy in the years ’30 of XX cent by a very active brick factory near Piacenza, RDB: the SAP system, that allowed building curved surfaces by prefabricating light elements. After WW2, this technique was applied also for the new structures covering wide spaces for the developing industry or also for public leisure, using prefabricated panels of the desired length. A particularly interesting application was the BISAP (double-SAP) panel that could be adapted for building large shells. In Codogno (LO), Italy, the BISAP panels were employed to cover a large sports hall, spanning about 37 × 26 m, without intermediate supports, resting (mainly) on the four corner pillars. Border pitch beams sustain at the top two crossed beams that separate (and support) the four hypar fields. On the four sides, two rafter beams are connected by horizontal prestressed tie beams, in order to minimize displacements and assure the preservation of the original shape. The first aim of the structural analysis was to assess the static conditions of the roof under the service loads assigned by Italian code for SLS, and then to evaluate seismic vulnerability at ULS of the whole sports hall, being a public space subjected to particular safety provisions. The FE code used (Straus7) allowed a very careful discretization of the orthotropic slab with the correct inclination and twist of the ribs, giving a reliable forecast of the behavior also in seismic conditions: the dynamic analysis of the modal shapes gives a satisfactory response of the shell, which maintains nearly unchanged his shape during free vibration modes. The seismic safety of the structure can be then increased by simply augmenting the stiffness of the four corner supports, where shear action is concentrated, by adding ribs to the L-shaped sections to form cross shaped ones. In this way also the slenderness (and weakness) of additional intermediated pillars could be overcome.

Anchorage of Reinforcement Bars in Hennebique R.C. Structures

Scipedia content — Tue, 30 Nov 2021 12:52:19 +0100

The Hennebique system was the most successful among the patented systems in the pre-code period even though the design rules were not completely clear. Anchorage of the re- inforcement is one of these unknown aspects and how it was calculated, and if it was calculated at all, is still today not clear. For this reason, the efficiency of the anchorages is one of the major issues when dealing with retrofitting a Hennebique structure or when its safety needs to be evaluated. In this paper a series of tests have been performed on the typical Hennebique an-chorages for reinforcing bars (fish-tails) and for the plate stirrups (bended ends) that were used. Different concrete types have been used so that either the collapse mechanisms of the anchor-ages and their ultimate strength may be identified.

Challenges in the Reuse and Upgrade of Pier Luigi Nervi‘s Structures

Scipedia content — Tue, 30 Nov 2021 14:15:39 +0100

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.

Conservation of 20th Century Concrete Heritage Structures in Cyprus: Research and Practice

Scipedia content — Tue, 30 Nov 2021 14:17:44 +0100

The conservation of 20th century concrete heritage structures poses a major
challenge worldwide. Whilst these structures possess a remarkable architectural value
and a rather experimental character in terms of the use of materials and technologies, at the
same time there is admittedly lack of recognition of their cultural and historical value by the
wide public. More often than not, such buildings are left to deteriorate and often they are even
demolished. This paper follows the workings of the project “CONSErvation of 20th century
concrete Cultural Heritage in urban changing environments” (CONSECH20). The
aforementioned international interdisciplinary project aims to investigate concrete
constructions built until 1965 in four different European countries (Cyprus, Italy, The
Netherlands and the Czech Republic), in terms of their architectural, social and historical
value, and to address their restoration and re-use potential. The paper initially presents
the significance of 20th century concrete heritage structures in general, and describes the
methodology proposed in order to ensure the protection of such buildings from demolition,
and facilitate their restoration and re-use (if and where possible) for the benefit of the
society. The focus is on the structural assessment and restoration of 20th century concrete
heritage buildings in Cyprus, following the methodologies described by modern codes for the
assessment and retrofit of existing concrete structures. A new practical analysis approach is
described and compared to the force-control approach of the pushover analysis of Eurocode
8:3, which significantly overestimates the demands for seismic upgrading. The two
aforementioned approaches are examined for a specific case study concrete heritage building
in Nicosia, Cyprus.

Conservation of Historical Reinforced Concrete Structures

Scipedia content — Tue, 30 Nov 2021 14:18:01 +0100

During the 20th century, reinforced concrete brought historical structural systems
back into modern times, transforming them into high-performance structures. Reflection on
early reinforced concrete structures of two ancient structural systems, the dome and the girder,
is presented through two Transylvanian monuments: the reinforced concrete cupola of the
Hungarian Theater of Cluj, the earliest structure of this type, and the one-way hollow block
slabs of Villa Tataru designed as a duet, by Gio Ponti and Elsie Lazar. Diagnosis and therapy
of the hundred-year old, “new” historical structures are described. Uncovering these
remarkable, but nearly unknown buildings, the paper intends to contribute to the understanding
of cultural heritage and to raise public awareness towards the fundamental principle of
UNESCO: “The cultural heritage of each is the cultural heritage of all”.

Decay Patterns and Damage Processes of Historic Concrete: A Survey in the Netherlands

Scipedia content — Tue, 30 Nov 2021 14:19:48 +0100

Historic concrete buildings (end of 19th century – 1960s), because of their
“experimental” character, require a specific approach to both survey and conservation.
Although they were built with empirical approaches, some buildings show a fair state of
conservation and resilience –even though they have already exceeded the 100-year
threshold– while others of comparable age are in severe need of restoration.
As part of the European project CONSECH20, aimed at contributing to the conservation
of cultural-heritage concrete buildings, this paper investigates what are the most common
types of damage and hypothetical causes, and what direct and non-direct parameters can lead
to a faster or slower deterioration of historic concrete in the Netherlands. The research is
based on an initial screening study, which will be used as a basis for a larger research among
the participant countries.
The current research is divided in three phases. Firstly, a selection of 15 case studies
from the Netherlands are investigated; the selection was based on criteria of age, state of
conservation and type of ownership. Secondly, the history and materials of the buildings
are examined. Thirdly, an on-site visual survey is performed per each building, with pre-
design templates, to identify types of damage, extent and severity. The data is then analysed
combining different factors with a calculated index of severity. Results are discussed and
contrasted to provide further clarification of the degradation of historic concrete. A fourth
phase, not discussed in this paper, will use this methodology in a broader context, with a
larger number of case studies in different countries.
The results indicate that the majority of types of damage are related to corrosion, being
the hypothetical cause carbonation-induced corrosion. The outcomes of the investigation
point out that the factors with a higher impact on the durability are the environment,
the use and maintenance of the buildings, the existence of a sacrificial plaster in exposed
elements, and the type of ownership.
Considering the limited number of buildings, the conclusions presented in this paper will
be further contrasted with a larger number of case studies.

Early Concrete Structures and Post-Patented Systems: Lessons to Preserve Early 20th Historical Heritage

Scipedia content — Tue, 30 Nov 2021 14:22:04 +0100

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.

Holistic Approach to Cleaning and Protection of Stone Façades of 20th Century Architectural Heritage

Scipedia content — Tue, 30 Nov 2021 14:28:12 +0100

Modern urban areas represent our recent past with great aesthetic and heritage value which should be maintained and preserved for the future. One of the best recognized landmarks of the city of Novi Sad, capital of Vojvodina region positioned in northern Serbia, is the architectural masterpiece Banovina Palace in which today resides provincial government. It is an elongated, closed, horseshoe-shaped structure, built in late 1930s in a modern style and influenced by expressionist architecture. Two-floor high with a tower on one end the building dominates the scenery and symbolizes the appearance of a large ship on the Danube River which flows in the immediate vicinity.
The façade of this famous building is covered with white marble from Adriatic island of Brac. After almost 80 years of exposure to weathering, urban pollution and manmade devastation, the façade was in need of cleaning, consolidation and protection. In the attempt to prepare for the European Capital of Culture 2021, the City of Novi Sad started ambitious project of local heritage revival. Due to awareness of lack of understanding about stone nature and behaviour, stone cleaning and protection usually raises concerns and cautious. The Laboratory for Materials in Cultural Heritage, Faculty of Technology, was invited to join the project to preform holistic characterisation of the stone, reveal deterioration mechanisms, and propose conservation methodology.
Using mobile laboratory with non-destructive techniques coupled with laboratory testing, the stone façade was comprehensively analysed. Various deterioration patterns were identified including patina, dirt deposits, eroding surfaces, yellow layers and black crusts, large amounts of carbonaceous particles responsible for black appearance of stone surface, soluble salts, microbiological corrosion, residue of inadequate graffiti removal, façade paints, acrylic binders, as well as mechanical damage of stone panels. Based on laboratory testing of a number of cleaning, consolidation and protection techniques and products, the most promising ones were also tested in situ [1]. Products ranging from traditional conservation approaches to innovative solutions like self-cleaning photocatalytic coating as final protective layer, were selected [2]. Resulting from research the methodology for cleaning, consolidation and protection was established in 2017 and implemented in 2019, where the laboratory acted again as scientific supervision and control of the conservation works. The presented approach allowed deep understanding of the complex problem and guaranteed responsible conservation strategy; therefore it stands as an example of 20th century architectural heritage preservation.

Reconstruction of a Masonry Windmill Tower with a Multi-Blade Wind Turbine, Steel Reservoir and Water Supply System

Scipedia content — Tue, 30 Nov 2021 14:40:03 +0100

In the early 20th century, rapid industrial growth around the world enabled the development of many advanced mechanical structures. Some of these structures were successfully used to improve agricultural efficiency or increase people’s comfort. Such a situation was observed in 1910 in the western part of Poland, which at the time was partitioned by Habsburg Austria, the Kingdom of Prussia, and the Russian Empire. In the city of Poznan, a Polish landlord built an advanced structure to automate his farming, using freely available wind energy. At first glance, it was a classic windmill, with a multi-blade wind turbine fixed to the top of a cylindrical masonry tower. However, some additional elements demonstrate the uniqueness of such a structure at the time. One hundred years later, the structure is located at the centre of a rapidly growing area of the city. For that reason, restoration of the tower is complex and requires the reconstruction of damaged or missing elements while observing new safety regulations. In this work, the author presents the basic assumptions necessary for the future renovation process.

Reinforced Concrete Floors in Historic Buildings from the Beginning and the Middle of the 20th Century - Examples of Structural Strengthening in the Process of Revitalization

Scipedia content — Tue, 30 Nov 2021 14:40:20 +0100

The paper presents a historical outline of structural solutions of reinforced concrete floors from the turn of the 19th and 20th centuries to the half of the 20th century in the Lower Silesia region of Poland. It is based on the analysis of archival documentation and expert research carried out during the design of the revitalization of historic public and industrial buildings. The structural typology of some simple RC floors slabs used in that time of introduction of concrete into construction life as well as constructional solutions of buildings erected in western Poland in those days are presented. Nowadays, while some of these buildings undergo refurbishment process to adapt them to new functional aims these RC floors have to be strengthened using different methods, depending on the assessment results. In some of the presented design study cases assessed technical state and load bearing capacity of floors ensure the possibility of their further use without the need for significant reinforcements, except for the need for surface material repairs. However, in some cases due to concrete deterioration processes and loss of its durability, despite necessity of material renovation, structural strengthening methods needed to be applied. For example, increasing the load bearing capacity of floors by making additional concrete layers cooperating with the existing reinforced concrete slab or by changing the static scheme by making new supports up to the complete replacement of floors (not only concrete ones) with modern, concrete rib-andbeam or composite ones were considered.

Senate Building of Canada Case Study: Seismic Rehabilitation

Scipedia content — Tue, 30 Nov 2021 14:45:48 +0100

Ottawa’s landmark Union Station was constructed between 1902 and 1912 to house Ottawa’s central railway station. Located in the Ottawa downtown core, it’s situated a short distance from Parliament Hill and across the street from the iconic Fairmont Chateau Laurier Hotel. In the early 1960s, the train tracks and train sheds were removed and replaced with Colonel By Drive parkway. The building sat vacant for quite some time, until it was revived when it underwent renovations in the early 1970s. A south addition was added with a unique geodetic canopy structure. The former Union Station had officially been adapted into the Government Conference Centre, which it remained until this rehabilitation project 2014-2018, which transformed the building into the temporary house of the Senate of Canada. The building was not accessible to the public when it was a Conference Centre, however since 2018 the building is again open to the public for the first time in 55 years.
The client’s objective for this rehabilitation was to increase useable floor space. A seismic upgrade of the existing heritage building was also required, along with the design of a new east addition. Existing floor plates required upgrading based on new user requirements. High heritage areas of the building had to be maintained in their original integrity and worked into the design upgrade.
Creative solutions were demanded to bring this existing heritage masonry building up to current seismic code, without the structure taking any more room within the floor spaces. Maximizing space was absolutely critical. As well as, ensuring the new building materials were compatible with the existing heritage building materials. Innovation was found in the balance between a minimal intervention approach and upgrading for current code requirements.

Structural Evaluation and Maintenance of Brooks Aqueduct Historic Site

Scipedia content — Tue, 30 Nov 2021 14:48:50 +0100

Brooks Aqueduct in Alberta, Canada is one of the largest and most sophisticated reinforced concrete aqueducts in the world. Now a national historic site, Brooks Aqueduct was built in 1914. The structure suffers from cracking and degradation in certain locations. To find out the possible main causes of potential overstress and damage in the different areas of the structure, it was evaluated by site inspections, some laboratory tests and analyzed numerically using Abaqus finite element software. Results of the numerical analysis are compared with the inspection and testing results and conclusions are made about the causes of deterioration and ways to conserve and repair the structure.

Structural Evaluation of the Greenhill Mine Tipple Structure Historic Site

Scipedia content — Tue, 30 Nov 2021 14:48:57 +0100

The tipple building located within the Greenhill Mine complex (a Provincial historic site) in southern Alberta, Canada is a reinforced concrete frame with a steel superstructure. The structure has been analyzed to assess its current state and the extent and causes of deterioration. The analysis is performed using data obtained from field and laboratory tests and evaluations and by using SAP2000 structural analysis software. Possible ways for conservation and restoration of the building for two different future uses are explored, and recommendations are provided.

The Safety Level of Concrete Pile Foundations under Industrial Monuments

Scipedia content — Tue, 30 Nov 2021 14:54:07 +0100

Prefabricated concrete piles have been used for the foundation of bigger buildings for about a century. Often a change in function, an addition (also vertically) or another type of alteration is required, resulting in different loads on the foundation.
There are several complicating factors that return regularly in these assessments. The first one is a lack of data. Often drawings are missing or incomplete, e.g. showing only pile head dimensions or maximum calculated load but not the pile length, pile tip shape or material properties. Inspection is hard and only possible for the part directly under the pile head. And a third complication is that in The Netherlands there have only been official codes for piles since 1992.
Various calculation and design methods from WWII until 1985 are discussed to see if there is any consistency that might lead to an indication of the load bearing capacity of piles in The Netherlands from that era.
It is concluded that design rules for the load bearing capacity of concrete pile foundations in The Netherlands have been inconsistent over time. If the original detailed geotechnical calculations and/or structural drawings cannot be found in archives then the given ultimate loads cannot only not be exceeded; even if the load on a pile is currently less than stated on the technical specifications designers are advised not to increase the load.