Construction Rehabilitation in Civil Engineering at bachelor degree level : A guideline course

In general terms, construction rehabilitation is not sufficiently studied worldwide in Civil Engineering Schools. In this article we propose an international guideline course for Rehabilitation of Constructions envisaged for Civil Engineering students at bachelor degree level. As we live in an increasingly globalized world, the course aims to prepare our students in the same basic concepts, so the course content and its focus can be common for all Civil Engineering programs worldwide. Nevertheless, the course should be considered as a general guideline, so that in each university, special attention should be paid to the topics that are most common due to the varying construction practices, preservation laws and regulations, and legal jurisdiction governing the scope of practice in construction rehabilitation, existing in the region/country in which the university is located. Moreover, in the authors’ opinion the guideline course should be focused on existing building types, both significant historic ones and those which make up the day-to-day rehabilitation market.


INTRODUCTION
The conservation of existing buildings is a fundamental principle in the cultural life of modern societies.In recent years, this topic has been the subject of extensive research, leading to development in the inspection, non-destructive testing, monitoring and structural analysis of constructions.However, the teaching of this topic has not received the same attention.The analysis of existing buildings creates challenges given the complexity of their geometry, the variability in the properties of traditional materials, the different construction techniques, the absence of knowledge about existing damage, and how certain actions affect buildings throughout their lifetime (Roca 2007).These challenges mean that existing buildings are subject to a number of difficulties in diagnosis and intervention, which in some cases limit the application of the regulatory requirements and existing guidelines in the general area of construction.Therefore, understanding, analysis and repair of buildings constitute one of the most important challenges for modern engineers (Lourenço et al. 2008).
In many countries, it is usual to act without devoting adequate resources to the study of why a construction requires intervention, mainly due to economic and time pressure.In fact, there have been aggressive interventions, causing a reduction in the value of the buildings, especially in the case of historically significant ones, or inappropriate The building rehabilitation and maintenance market is one of the most important economic sectors in construction, especially in the most developed societies.For instance, in Europe, in 2010, rehabilitation and maintenance was a major market, accounting for 28% of construction output with a value of 332•10 6 € (FIEC 2010), and in the USA, this sector also accounts for an important fraction of the construction market.In addition, there are many other factors which indicate that the rehabilitation market has high growth potential in many countries: the growing social awareness that preservation and enjoyment of the building heritage has acquired, the favorable prospects offered in certain areas by the cultural sector as an engine for activity (Cultural Tourism), the progressive ageing of existing housing, etc.Moreover, the rehabilitation sector is a key topic in terms of sustainable urban growth: promoting lower energy consumption (in contrast with demolition and new work), consuming less material than new construction work, etc.

Focus of the guideline course
In construction rehabilitation there is wide variety of policies with extreme situations.To design a guideline course, first of all, we should ask ourselves some basic questions: When should a structure be rehabilitated?What procedure should be adopted during the inspection?Do students have previous knowledge about the behavior of traditional materials and about newly applied ones?What is more, we could add another question to all of these: Why?The civil engineer, at the design level (Dally et al. 2012), should be able to adopt an approach when answering these questions.
On the other hand, we must pay attention to highlighted historic buildings, whose need for rehabilitation and maintenance is especially significant because their potential failure has important consequences (from technical, cultural and economical points of view).In this type of construction the provision of rehabilitation protocols to be adopted must be carefully considered.Nevertheless, there are existing buildings, which are not unique from the cultural point of view, but which must be rehabilitated, sometimes simply due to changes in functionality or habitability.Their lesser singularity does not preclude requiring similar exhaustive analysis.Besides, this day-to-day rehabilitation market contributes significantly to the economy of the construction sector.In the authors' opinion, both types of buildings must be targeted by the educational proposal.
All these circumstances result in the need for specific training of engineers dedicated to this area, including Civil Engineers.

NEED FOR CONSTRUCTION REHABILITATION COURSE
This article culminates in the selection of topics integrating all the information generated throughout the research.However, as a previous justification, in the following section, we introduce some of the topics considered important in order to complete the construction rehabilitation guideline course.
Due to the previously mentioned challenges of analyzing existing buildings, we have to adopt a general methodology through consensus.As an example, Figure 1 illustrates a rational analysis procedure (Lombillo 2010).
Within these phases, previous knowledge is fundamental in choosing the most suitable techniques and materials applicable in later stages of Design/Project and Work (Binda et al. 2009).Moreover, carrying out these preliminary studies will lead to a reduction both in overall costs of the intervention and in the working times (Lourenco et al. 2008), since these phases of previous study (phases 1-3) can limit the uncertainty in the intervention.
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Therefore, we should base the rehabilitation process on a precise preliminary investigation (Binda et al. 2008), in order to document the current state of the construction.So, we should approach the rehabilitation process from a multidisciplinary point of view, considering the previously mentioned complementary aspects including: the historical evolution of the buildings, geometry, cracking patterns, characteristics of the materials, construction technology, potential failure mechanisms, etc. (Penazzi et al. 2000).In this regard, collaboration is essential among architects, engineers, chemists, restorers, historians, archaeologists, etc.In this sense, Binda et al. (2000) suggest, in relation to studies carried out for the rehabilitation of the "Torrazzo" of Cremona (Italy): "The multidisciplinary nature of the working method is the fundamental key to the successful development of the investigation".
At this point, we have sufficient motivation to ask the question: What construction types should we train Civil Engineers in?The following paragraphs give details about them.
Most historical monuments are masonry buildings, as are many residential buildings, and there is also an extensive number of civil engineering structures, bridges, retaining walls and reinforcement in highways, etc.In Europe alone, according to the International Council on Monuments and Sites (ICOMOS), there are 500,000 registered monuments: 20% have structural problems, of which 40% may be categorized as masonry constructions/buildings, which implies 40,000 possible interventions on existing buildings, to which we could add a number of civil engineering structures (infrastructures, bridges, etc.) (Garmendia 2010).Therefore, the creation of a teaching A large part of the world's population lives or works in earthen buildings (Houben and Guillaud 1989).As a reference, as of March 2012, of the 563 cultural heritage sites that the World Heritage Committee has inscribed in its list, 96 (17%) are completely or partially built of earth (Unesco 2012).We can find earthen constructions practically all over the world, with a special importance in developing countries, where they still use other building materials limitedly and traditional construction is still common.In any case, earthen construction is more sensitive than its modern counterpart, as it is more vulnerable to external agents.These considerations highlight the need to take into account effective diagnostic techniques to help assess the state of conservation of earthen architecture, and adopt intervention methods in order to preserve these constructions.
In the United States, an important part of the population lives in houses constructed almost entirely of wood, but only a small minority of students entering graduate programs in structural engineering and materials science choose to specialize in timber (Langenbach 2010).In Germany for example, only 14% of all single family houses and negligible numbers of other buildings are constructed of timber (Betz 2006).In large parts of China, timber used to be in common use for buildings.Today, wood construction has been almost entirely displaced by concrete, even in smaller settlements.
Traditional constructions, either common buildings or historic and monuments, have used timber extensively for structures supporting floors and roof trusses.At worldwide level there are lots of residential, religious or military timber structures.As an example, Figure 2 shows a wooden support in a historic building in a rural part of Spain.In steel for a structural rehabilitation application, we must take into account many variables (Lombillo et al. 2011;Thomas et al. 2010), the most influential of which are chemical composition and microstructure.We should highlight that we could avoid numerous pathological processes, such as the effects of certain types of corrosion, merely by applying basic materials science concepts.In this particular case, Figure 3 shows galvanic corrosion between the base of a galvanized steel column and carbon steel bolts.If we take into consideration the Uhlig report, the construction sector could save approximately 20% of the costs caused by corrosion if the correct anticorrosion measures were taken.
Finally, among other topics, there is a need to provide a minimal knowledge base in the seismic behavior of existing buildings in order to minimize the damaging effects of earthquakes in constructions.

METHOD OF GUIDELINE COURSE DEVELOPMENT
One of the challenges is to sufficiently unify the criteria of an optional course with great impact on society, training our students in the basics, with a proposal of a common course and focus in all the Civil Engineering degrees worldwide.Logically, we should consider the approach as a general guide, since each university should pay special attention to the topics that are most common in its constructive practices, taking into account the regional and national reality.with more completely at post-graduate level than at the bachelor degree level (Figure 5).
In addition, not all the topics covered in the survey are taught with the same preference.
At the bachelor degree level, there is less content related to old buildings compared to modern ones.Thus, explanation of general and methodological concepts, examples of pathology reports and previous studies, and rehabilitation of concrete structures are the most commonly discussed topics at the bachelor degree level.This is confirmed by more than 70% of the surveys.In postgraduate study, as well as some of the previously mentioned, over 70% of respondents explain examples of intervention in old buildings.
In contrast, the least studied topics are rehabilitation of earthworks (17% in the bachelor degree and 8% in postgraduate), strategies for monitoring and control of buildings (37% and 31% respectively), concepts about the history of construction (37% and 46%), aspects related to intervention in foundations of buildings, whether old or modern, and the rehabilitation of steel and cast iron structures (34% bachelor's degree and 46% Rehabilitation course, as there was less dedication to content related to old buildings than to modern ones.Furthermore, the above reference listed a series of contents, complementary to those included in the questionnaire, which part of the respondents reported dealing with in their subjects.In this sense, due to the repetition found, we should highlight the following: Assessment of existing structures (in-situ inspection, inlaboratory investigation techniques and monitoring), seismic behavior of existing buildings, and technology for rehabilitation of non-structural anomalies in buildings (humidity problems, roofs and facades).We also took all these contents into account to propose a comprehensive guideline for the Construction Rehabilitation course.
We grouped the topics in eight large blocks and we assigned teaching hours (Table 1).
As can be seen, face-to-face teaching accounts for a total of 60 hours.
We considered it necessary to include a block of practical contents consisting in visits to buildings under rehabilitation, workshops with professionals involved in rehabilitation of buildings and practicals in Laboratories.The aim of this practical block is to introduce the students to professional responsibilities and investigation.

Expert review
Among the colleagues who responded to the questionnaire, we selected three internationally renowned professors in the Construction Rehabilitation area to provide their opinions on the preliminary guideline course which we had elaborated.
Table 2 shows, in the first three columns, the proposed teaching content and the preassigned teaching hours.
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The next six columns integrate the experts' opinions related to the relevance of each of the topics (greater, medium or minor) and the time they consider necessary to dedicate to each topic (more, the same or less)."Minorrelevance" means that they could be important for other courses but, here, the students should already know them.The column with "less time" does not represent a low appreciation of the item but, in some cases, exactly the opposite; for example "foundations" is quite complex and long, as well as "calculation" or "history of construction" and cannot be deeply considered in this course, so they must remain simple "pointers" to other courses or publications.
To facilitate the readers' interpretation of the table, for example, in the case of the first aspect "I.1.-Generalconcepts: Building Pathology and Rehabilitation" one of the three experts considered it to have great relevance and two medium relevance, and all three considered the pre-assigned teaching hours to be suitable.
Based on the most relevant conclusions extracted from the experts' opinions, the initial guideline was rewritten.Fundamentally, in relation to the pre-assigned times, we reduced the dedication to topics such as "I.2.-Notions about the history of construction / historic construction systems", "III.1.-Foundations"and "V.1.-Effects of earthquakes on constructions".In contrast, we increased the dedication to the following topics: "I.3.-Generalmethodology", "V.2.-Methodologies for the seismic safety assessment of constructions" and "V.3.-Seismicstrengthening solutions".We would like to highlight that none of the topics was eliminated due to the opinions of the experts.

I.4.-Provisional scaffolding (1.0 h).
A topic related to the appropriate codes, standards, regulations, government requirements and project funding sources may be considered in the course.

II.-Assessment of Existing Structures (12.0 h).
II.1.-Theimportance of identifying the structural system (1.0 h).Finally, due to the time constraints of the course and the magnitude of the topics included, certain contents could be more suitable for inclusion in other courses, for example, the topic of rehabilitation of non-structural anomalies in buildings, the highly complex topic of analysis of the structural safety of existing constructions or the block devoted to seismic behavior of existing buildings.

II.2.-In
As a final comment, it is necessary to recognize that it is important to survey both business and practicing engineers' perspectives on educational needs in Construction Rehabilitation before further developing this course in the University.Therefore, with the objective of polishing the guideline course based on practical and social demands, the survey of professional opinion should be the next step to develop in a future study.
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The authors wish to thank all those colleagues from around the world who devoted some of their precious time to answer our questions and share their experience in the subject, without whom this study would not have been possible.Supervised activity in which the students work in groups and receive assistance and guidance when necessary (in optional classes).This may include the presentation of these works.

15
Individual reflection Study of content related to the "theoretical classes": This includes any study activity that has not been included in the previous sections (study for exams, library work, complementary reading, etc.).

30
Total hours of autonomous work: 90 60% 150 h 100% Accepted Manuscript Not Copyedited not solve the problem.It is therefore necessary to make some recommendations to ensure implementation of rational analysis and rehabilitation methods.
module dealing with rehabilitation of masonry structures is necessary in Civil Engineering degrees.However, research and advanced studies of historical masonry structures have progressed slowly in comparison to work on other structures made of materials, leading to a notable absence of knowledge and experience in this field.
We took precautions when unifying the responses due to the priority that each experience (lecturer/university, region or country) gives to a specific aspect.In this section a sequential program directed to students of Civil Engineering at the bachelor degree level is proposed with minimum contents that could provide a starting point in any country in the world.concepts (1.0 h): Building Pathology and Rehabilitation.Criteria and principles for conservation of existing buildings.I.2.-Notions about history of construction, construction systems and construction details (1.5 h).I.3.-Generalmethodology (2.5 h): Study of the existing information, Diagnosis, Design, Execution and Control of work, and Maintenance.
-situ inspection: Non or Minor Destructive Techniques (3.0 h): Techniques applied to masonry structures, timber structures, concrete structures and structures of iron-based alloys.II.3.-In-laboratoryinvestigation techniques (2.0 h): Laboratory tests on samples extracted from homogeneous material.Laboratory tests on heterogeneous material.II.4.-Monitoring (1.5 h): Sensor types.Typologies of acquisition systems and remote transmission of data.
to the analysis of the structural safety of existing constructions (1.5 h): Past-performance (analysis of the historic behavior of constructions).Integration of experimental and analytical perspectives in the determination of construction safety (structural reliability).(2.0 h): Typologies of foundations.Origin of failure in foundations.Symptoms of failure in foundations, causes and applicable therapy.Actuations on the soil.III.2.-Masonry structures: Brickwork or stone bearing walls (and columns) (3.0 h): Notions about materials: bricks, stones, mortars, masonries, special materials adopted for rehabilitating or strengthening structures.Mechanics of masonry in compression, tension, shear, out-of-plane bending.Structural-type pathological processes and applicable therapy.III.3.-Masonrystructures: Arches, vaults and domes (1.0 h): Historic development of mechanics of arches vaults and domes.Structural-type pathological processes and applicable therapy.III.4.-Timber structures (3.0 h): Wood as a construction material.Structural-type pathological processes and applicable therapy.Pathological processes due to biotic damage and applicable therapy.Wood protection.III.5.-Earthen construction rehabilitation (1.0 h): Historic rammed-earth construction worldwide distribution.Notions about materials: Rammed earth and

Figure 3 :
Figure 3: Galvanic corrosion between the base of a galvanized steel column and carbon steel bolts.

Figure 5 :
Figure 5: Radial diagram of the teaching intensity in different topics related to construction rehabilitation worldwide (per unit).
Journal of Performance of Constructed Facilities.Submitted July 2, 2013; accepted November 11, 2013; posted ahead of print November 13, 2013.doi:10.1061/(ASCE)CF.1943-5509.0000540Copyright 2013 by the American Society of Civil Engineers This scenario changes in every country and is directly affected by environment, local policies and industrial activity.However, any such changes are merely quantitative; the overall picture remains quite similar for all European countries.Iron-based alloy structures are fundamental in construction and rehabilitation of buildings.One of the factors to be considered is kinetic attack, given that most structures are exposed to the weather, under different types of atmospheres, the most aggressive being industrial marine conditions.Therefore, if we choose a specific type of Journal of Performance of Constructed Facilities.Submitted July 2, 2013; accepted November 11, 2013; posted ahead of print November 13, 2013.doi:10.1061/(ASCE)CF.1943-5509.0000540Copyright 2013 by the American Society of Civil Engineers strategies, thus minimizing alterations and loss of value and significance (Tsai and D'Ayala 2011).To sum up, the reintroduction of engineering classes that focus on the science and structural engineering of buildings with timber is urgent (Langenbach 2010), and especially teaching aimed at the rehabilitation of existing wooden structures.There are more than 160 million buildings in Europe, 80% of which are structures made with reinforced concrete or unreinforced masonry, and over 25% are pre-1960 according to Housing Statistics in the EuropeanUnion, 2004 (Boverket and MMR   2005).We will have to restore, rehabilitate, partially reconstruct or demolish a large number of these buildings, built during the construction boom in the 1950s and 1960s.A considerable percentage of the housing stock is beginning to need interventions, some of which are structural.
postgraduate).Therefore, in view of these results, we propose more evenly balancing the intensity of dealing with different topics suitable for inclusion in the Construction Journal of Performance of Constructed Facilities.Submitted July 2, 2013; accepted November 11, 2013; posted ahead of print November 13, 2013.doi:10.1061/(ASCE)CF.1943-5509.0000540Copyright 2013 by the American Society of Civil Engineers university should review the course's contents to adapt them, in every moment, to the needs of the industrial sector, and society in general.After an extensive study in which university professors from carefully selected countries have participated, we have proposed topics that should be considered within a Construction Rehabilitation course.Moreover, we have also proposed that this course should involve 60% of autonomous work by students, of which the so-called individual reflection, based on the assimilation of meticulously prepared case studies, should have particular relevance.The other 40% would be traditional lectures with explanations of content by teachers, including demonstrations.In this way, we wish to highlight the importance of previous study to achieve appropriate diagnosis, a key phase, in the authors' opinion, in any rehabilitation process.
IV.2.-Structures of iron-based alloys (steel and cast iron) (3.0 h): Historical introduction to metallic structures.Material used in steel structureshistorical review.Mechanical properties of cast iron, mild iron and steel in existing structures.

Table 4 :
Methodology of teaching-learning