**3. Historical masonry construction techniques**

The basic method of construction has barely changed in several thousand years: the units are placed one above the other in such a way that they form an intertwined assembly in at least two horizontal directions. Sometimes order is achieved in the third dimension. Most of the time, an intermediate layer of mortar is used to save small to large inaccuracies between units and make the walls waterproof, airtight and soundproof.

There are four main techniques for achieving stable masonry [8]:


**Figure 4.**

*Photographs of Mendoza, Argentina: (a) prehispanic stone walls (Uspallata), (b) stone bridge (Luján de Cuyo), (c) Jesús Nazareno church (Guaymallén).*

**Figure 5.**

*Photographs of historical masonry heritage of Mendoza, Argentina: (a) provincial Museum of Fine Arts (Luján de Cuyo), (b) Caro wine vault (Godoy Cruz), (c) Arizu winery (Godoy Cruz).*


#### **4. Seismic behaviour of historic masonry**

The behaviour of historical masonry to permanent vertical loads has been satisfactory. A different approach to heritage building occurs when there is a seismic-risk region. The way in which a structure is damaged during an earthquake is strongly influenced by its proximity to the area of fault rupture.

Under the great demands on acceleration and displacement of the seismic events studied, only the conjunction updated with new design procedure regulations, a regular good structural design, static redundancy and proper implementation will allow structures to survive strong earthquakes [2].

By definition, "repair" refers to the post-earthquake repair of damage, caused by seismic ground motion that does not increase the seismic resistance of a structure beyond its pre-earthquake state.

"Strengthening", "seismic strengthening", or "seismic upgrading", however, comprises technical interventions in the structural system of a building that improve its seismic resistance by increasing strength and ductility. According to the proposed terminology, strengthening a building before an earthquake is called "rehabilitation", whereas strengthening after the earthquake is called "retrofit" [9].

The law procedure and how to decide the appropriate methods are different in each country. However, the practice between safety and historical preservation is almost the same in all countries that have some preservation regulations,

**61**

*Historic Masonry*

the building [3].

**4.1 Masonry laboratory tests**

in the last 25 years [3, 9].

dynamic monitoring.

and inside the walls.

**5. Historic masonry durability**

*DOI: http://dx.doi.org/10.5772/intechopen.87127*

behaviour of the frames where the masonry is inserted.

forced concrete of that time, appearing the armed masonry.

cially the masonry constructions in adobe and in stone [3, 11, 12].

evaluations that have less thickness than the historic masonry.

but the problems are exacerbated when the effect of seismic actions is added. The California Historical Construction Code [10] has joined the vision regarding heritage aspects and safety. It includes the subject of use and occupation; protection against fire; escape routes and accessibility; structural requirements, materials and old methods of construction; requirements of mechanical and electrical installations; and drains, whenever the building merits the identification of heritage value. In the United States, the bearing walls of unreinforced masonry (URM) correspond to before 1933 with two courses of bricks joined at their upper end. When the interior was filled with rubble, it was stiffened elastically and modified the

The behaviour of horizontal diaphragms in historic masonry is often deficient because they are not sufficiently connected to transfer the horizontal seismic forces to the resistant side walls. They are usually made of wood, supported by beams anchored in wall inserts, which are affected by deformations outside the plane of the loaded wall, which can lead to the overturning of the wall and the collapse of

The Long Beach earthquake (California, 1933) showed the bad behaviour of this masonry, causing the prohibition to use it in school buildings. The UBC of 1943 established that the masonry had to meet the same criteria of design of the rein-

The Santiago (Chile) and City of México (1985); Izmit, Turkey, and Quindío, Colombia (1999); Pisco, Perú (2007); L'Aquila, Italy (2009); Lorca, Spain (2011); Kathmandú, Nepal (2015); and Manabí, Ecuador (2016) earthquakes have shown that nonengineering masonry buildings have suffered significant damage, espe-

The tests of historic masonry specimens obtained from existing structures are scarce. However, there are several investigations carried out in small-scale replicas of URM or in different scales carried out in the United States, Italy and Yugoslavia

There are in situ testing techniques to measure the compressive strength of the masonry, which produce some damage and require special equipment. The experimental static tests can be applied: flat-jack test and pull out. Ultrasonic, geo-radar, acoustic emission, static monitoring, thermography, X-ray diffraction can be used as non-destructive tests; which sometimes are not justified for masonry routine

The dynamic tests can be ambient vibration testing, even to register a long-term

From the point of view of durability, the walls as an open system are in contact

with other contiguous structures that take part in the dynamics of the overall behaviour. Even when any infiltration can be successfully eliminated, contact with the ground or with adjacent walls provides moisture sources by capillarity. Virtually all walls contain soluble salts, either dispersed within porous materials or locally concentrated. They can be present as efflorescence that form different aggregates of crystals with various shapes and located on the surface, such as sub-springs that form crystalline aggregates below the surface, and as solutes in aqueous solutions on

#### *Historic Masonry DOI: http://dx.doi.org/10.5772/intechopen.87127*

*Heritage*

**Figure 4.**

**Figure 5.**

*Cuyo), (c) Jesús Nazareno church (Guaymallén).*

3.Small-to-medium units are made to normal precision in few sizes and assembled to a basic grid pattern, and the inaccuracies are taken up by use of a packing material such as mortar (e.g. normal brickwork, see **Figure 5**).

*Photographs of historical masonry heritage of Mendoza, Argentina: (a) provincial Museum of Fine Arts* 

*Photographs of Mendoza, Argentina: (a) prehispanic stone walls (Uspallata), (b) stone bridge (Luján de* 

4.Irregularly shaped and sized pieces are both packed apart and bonded together

The behaviour of historical masonry to permanent vertical loads has been satisfactory. A different approach to heritage building occurs when there is a seismic-risk region. The way in which a structure is damaged during an earthquake

Under the great demands on acceleration and displacement of the seismic events studied, only the conjunction updated with new design procedure regulations, a regular good structural design, static redundancy and proper implementation will

By definition, "repair" refers to the post-earthquake repair of damage, caused by seismic ground motion that does not increase the seismic resistance of a structure

"Strengthening", "seismic strengthening", or "seismic upgrading", however, comprises technical interventions in the structural system of a building that improve its seismic resistance by increasing strength and ductility. According to the proposed terminology, strengthening a building before an earthquake is called "rehabilitation", whereas strengthening after the earthquake is called "retrofit" [9]. The law procedure and how to decide the appropriate methods are different in each country. However, the practice between safety and historical preservation is almost the same in all countries that have some preservation regulations,

with adherent mortar (e.g. random rubble walls).

*(Luján de Cuyo), (b) Caro wine vault (Godoy Cruz), (c) Arizu winery (Godoy Cruz).*

is strongly influenced by its proximity to the area of fault rupture.

**4. Seismic behaviour of historic masonry**

allow structures to survive strong earthquakes [2].

beyond its pre-earthquake state.

**60**

but the problems are exacerbated when the effect of seismic actions is added. The California Historical Construction Code [10] has joined the vision regarding heritage aspects and safety. It includes the subject of use and occupation; protection against fire; escape routes and accessibility; structural requirements, materials and old methods of construction; requirements of mechanical and electrical installations; and drains, whenever the building merits the identification of heritage value.

In the United States, the bearing walls of unreinforced masonry (URM) correspond to before 1933 with two courses of bricks joined at their upper end. When the interior was filled with rubble, it was stiffened elastically and modified the behaviour of the frames where the masonry is inserted.

The behaviour of horizontal diaphragms in historic masonry is often deficient because they are not sufficiently connected to transfer the horizontal seismic forces to the resistant side walls. They are usually made of wood, supported by beams anchored in wall inserts, which are affected by deformations outside the plane of the loaded wall, which can lead to the overturning of the wall and the collapse of the building [3].

The Long Beach earthquake (California, 1933) showed the bad behaviour of this masonry, causing the prohibition to use it in school buildings. The UBC of 1943 established that the masonry had to meet the same criteria of design of the reinforced concrete of that time, appearing the armed masonry.

The Santiago (Chile) and City of México (1985); Izmit, Turkey, and Quindío, Colombia (1999); Pisco, Perú (2007); L'Aquila, Italy (2009); Lorca, Spain (2011); Kathmandú, Nepal (2015); and Manabí, Ecuador (2016) earthquakes have shown that nonengineering masonry buildings have suffered significant damage, especially the masonry constructions in adobe and in stone [3, 11, 12].

#### **4.1 Masonry laboratory tests**

The tests of historic masonry specimens obtained from existing structures are scarce. However, there are several investigations carried out in small-scale replicas of URM or in different scales carried out in the United States, Italy and Yugoslavia in the last 25 years [3, 9].

There are in situ testing techniques to measure the compressive strength of the masonry, which produce some damage and require special equipment. The experimental static tests can be applied: flat-jack test and pull out. Ultrasonic, geo-radar, acoustic emission, static monitoring, thermography, X-ray diffraction can be used as non-destructive tests; which sometimes are not justified for masonry routine evaluations that have less thickness than the historic masonry.

The dynamic tests can be ambient vibration testing, even to register a long-term dynamic monitoring.

#### **5. Historic masonry durability**

From the point of view of durability, the walls as an open system are in contact with other contiguous structures that take part in the dynamics of the overall behaviour. Even when any infiltration can be successfully eliminated, contact with the ground or with adjacent walls provides moisture sources by capillarity. Virtually all walls contain soluble salts, either dispersed within porous materials or locally concentrated. They can be present as efflorescence that form different aggregates of crystals with various shapes and located on the surface, such as sub-springs that form crystalline aggregates below the surface, and as solutes in aqueous solutions on and inside the walls.

**Figure 6.** *Evolution of the mortar compatibility process during rehabilitation of school building [2].*

The main known salts produced in the walls are carbonates, sulphates, chlorides, nitrates, oxalates and sodium, potassium, calcium, magnesium and ammonia. The different salt species, precipitated from multicomponent systems, vary considerably depending on the materials present, but the type of salt found can, therefore, very often give indications of their origin.

Both the plasters and the paint layer of the walls are typically open structures with high porosity (their pores can easily be intercommunicated). This means that there is a large surface exposed to the degradation agents and there is easy permeability to fluids in contact with it both liquids (solutions of salts diluted in the wall) and gases (atmospheric pollutants and water vapour) [13].

#### **5.1 Material's compatibility**

In masonry it is required that the chemical compatibility between the mortar of replacement and the old mortar, the physical compatibility in relation to the process of solubility of salts and water of transport and the structural compatibility where the resistance of the new mortar must be similar to that of the masonry historical in order to avoid damages by the use of mortars with Portland cement.

As far as mortars are complex systems, different approaches can be used for their characterisation. Nowadays, the reconstruction of the original composition is quite complex and requires the application of various and complementary techniques. In addition, the technological culture of making lime mortars has been lost, although from the economic point of view they would be of lower cost [7]. The need for mortar compatibility has led to the design of specific products to avoid damage by chemical reactions as shown in **Figure 6** [2].

## **6. Masonry modelling**

The directed behaviour of the geomaterials (shear as a function of compressive strength) requires computational models that allow capturing the different failure modes and, without losing precision, represent them in a simple way. In accordance with this, there are several modelling techniques; the micro-models consist of the modelling of the masonry units and the mortar as continuous elements, while the

**63**

**Figure 8.**

*Historic Masonry*

desired [14].

of flat-jack in situ.

the tests.

**Figure 7.**

*Comparison of stress state modelling and building damage status [17].*

*Comparison between stress state modelling and building damage status [17].*

*DOI: http://dx.doi.org/10.5772/intechopen.87127*

masonry-mortar interface is represented by means of discontinuous elements. As the macro-models, these are phenomenological models in which masonry units, mortar and interface are represented as a composite by means of a continuous element. The technique to be used is based on the level of accuracy and simplicity

Phenomenological models allow focusing on the overall response of the structure at a lower computational cost. For this to happen, it is necessary to establish a constitutive model whose response is representative of the behaviour of the composites. The constitutive model of Drucker-Prager [15, 16] allows to represent the behaviour of the masonry as an elasto-plastic material with a strong dependence on the acting pressure. The low number of variables to define makes this model attractive. In turn, the characterisation of these variables can be carried out in a simple way through a diagonal compression test in laboratory or application

To obtain the modelling parameters of the masonry, laboratory tests are carried out in a 1:1 scale on specimens of different thickness [15]. With the experimental results achieved, a finite element model is formulated using the Abaqus software [16] whose parameters allow to obtain a behaviour similar to that observed during

#### *Historic Masonry DOI: http://dx.doi.org/10.5772/intechopen.87127*

*Heritage*

**Figure 6.**

The main known salts produced in the walls are carbonates, sulphates, chlorides, nitrates, oxalates and sodium, potassium, calcium, magnesium and ammonia. The different salt species, precipitated from multicomponent systems, vary considerably depending on the materials present, but the type of salt found can, therefore,

Both the plasters and the paint layer of the walls are typically open structures with high porosity (their pores can easily be intercommunicated). This means that there is a large surface exposed to the degradation agents and there is easy permeability to fluids in contact with it both liquids (solutions of salts diluted in the wall)

In masonry it is required that the chemical compatibility between the mortar of replacement and the old mortar, the physical compatibility in relation to the process of solubility of salts and water of transport and the structural compatibility where the resistance of the new mortar must be similar to that of the masonry historical in

As far as mortars are complex systems, different approaches can be used for their characterisation. Nowadays, the reconstruction of the original composition is quite complex and requires the application of various and complementary techniques. In addition, the technological culture of making lime mortars has been lost, although from the economic point of view they would be of lower cost [7]. The need for mortar compatibility has led to the design of specific products to avoid damage by

The directed behaviour of the geomaterials (shear as a function of compressive strength) requires computational models that allow capturing the different failure modes and, without losing precision, represent them in a simple way. In accordance with this, there are several modelling techniques; the micro-models consist of the modelling of the masonry units and the mortar as continuous elements, while the

very often give indications of their origin.

chemical reactions as shown in **Figure 6** [2].

**5.1 Material's compatibility**

**6. Masonry modelling**

and gases (atmospheric pollutants and water vapour) [13].

*Evolution of the mortar compatibility process during rehabilitation of school building [2].*

order to avoid damages by the use of mortars with Portland cement.

**62**

masonry-mortar interface is represented by means of discontinuous elements. As the macro-models, these are phenomenological models in which masonry units, mortar and interface are represented as a composite by means of a continuous element. The technique to be used is based on the level of accuracy and simplicity desired [14].

Phenomenological models allow focusing on the overall response of the structure at a lower computational cost. For this to happen, it is necessary to establish a constitutive model whose response is representative of the behaviour of the composites. The constitutive model of Drucker-Prager [15, 16] allows to represent the behaviour of the masonry as an elasto-plastic material with a strong dependence on the acting pressure. The low number of variables to define makes this model attractive. In turn, the characterisation of these variables can be carried out in a simple way through a diagonal compression test in laboratory or application of flat-jack in situ.

To obtain the modelling parameters of the masonry, laboratory tests are carried out in a 1:1 scale on specimens of different thickness [15]. With the experimental results achieved, a finite element model is formulated using the Abaqus software [16] whose parameters allow to obtain a behaviour similar to that observed during the tests.

**Figure 7.** *Comparison of stress state modelling and building damage status [17].*

**Figure 8.** *Comparison between stress state modelling and building damage status [17].*

Based on the model generated and calibrated, the building geometry and the state of applicants loads are simulated, the results of which are compared with the real damage evidenced in the structures analysed. The analysis of the results from

**Figure 9.** *Simulation of facade damage due to inefficient foundation [17].*

**65**

**Table 1.**

*Historic Masonry*

*DOI: http://dx.doi.org/10.5772/intechopen.87127*

sector and the lateral ones [18].

**Evaluated Saint Francis** 

Charge heritage National

Intended use Outdoor

Archaeological and historical background

*Data on the buildings studied.*

in Mendoza, Argentina, from 1999 to 2015 [2].

masonry buildings prior to the value enhancement [2].

**Ruins, Capital**

Date of building XVIII century Late nineteenth

Direction Architecture Municipality of Capital

museum

Historical and archaeological studies

**7. Study cases**

proposal for its repair and subsequent rehabilitation.

the structural simulation allows a better understanding of the causes of the deterioration as well as the cracking patterns. These results have allowed us to make a

**Figure 7** shows the general structural model and the state of stresses of the masonry of an educational building [17]. It shows the concentration of stress associated with the wall encounters and points of application of loads, points that must be reinforced locally, while the rest of the masonry is subjected to a normal tension level below the stress maximum. In **Figure 8** we can see the result of the modelling for the damage in archs, and **Figure 9** shows the detachment of the main facade. In the case of the museum in **Figure 10**, the stress concentration in the walls of the central nave is observed as a result of the differential settlement between this

**Table 1** shows the cadastral characteristics of historic masonry buildings studied

**Table 2** shows the data obtained in the evaluation of the condition of the historic

**Table 3** shows the soil criteria and masonry modelling for different buildings studied. It is taken as a criterion modelling by finite elements for walls using the type plate element of four or eight nodes. Drucker-Prager model has been used for the simulation of material failure [15]. The foundation is modelled by elastic springs, or the soil is modelled directly, considering its rigidity (elastic), since in this type of structure soil stiffness plays a fundamental role. For the roof structure, which is generally flexible, main resistance elements such as trusses or girders (ridges, etc.) are modelled, distributing loads to these elements. The seismic action is determined by applying the methods established by the regulations as propor-

> **Mitre School, Capital**

> century−1906

Direction of Heritage Government of Mendoza

Educational museum

Few historical and archaeological studies

Date of study 1999 1999 and 2010 2012 2013

**Giol Chalet, Maipú**

Municipality of Maipú National Direction Architecture

Few historical studies. No archaeological studies

1910 1892 house

Vintage museum Fine arts museum

**Fader House, Luján de Cuyo**

1905–6 paints

Direction of Heritage National Direction Architecture

Few historical studies. No archaeological studies

tional forces to the mass of each node of the finite element mesh [17].

**Figure 10.** *Damage due settlements of different sectors [18].*

#### *Historic Masonry DOI: http://dx.doi.org/10.5772/intechopen.87127*

the structural simulation allows a better understanding of the causes of the deterioration as well as the cracking patterns. These results have allowed us to make a proposal for its repair and subsequent rehabilitation.

**Figure 7** shows the general structural model and the state of stresses of the masonry of an educational building [17]. It shows the concentration of stress associated with the wall encounters and points of application of loads, points that must be reinforced locally, while the rest of the masonry is subjected to a normal tension level below the stress maximum. In **Figure 8** we can see the result of the modelling for the damage in archs, and **Figure 9** shows the detachment of the main facade.

In the case of the museum in **Figure 10**, the stress concentration in the walls of the central nave is observed as a result of the differential settlement between this sector and the lateral ones [18].

## **7. Study cases**

*Heritage*

**Figure 9.**

*Simulation of facade damage due to inefficient foundation [17].*

Based on the model generated and calibrated, the building geometry and the state of applicants loads are simulated, the results of which are compared with the real damage evidenced in the structures analysed. The analysis of the results from

**64**

**Figure 10.**

*Damage due settlements of different sectors [18].*

**Table 1** shows the cadastral characteristics of historic masonry buildings studied in Mendoza, Argentina, from 1999 to 2015 [2].

**Table 2** shows the data obtained in the evaluation of the condition of the historic masonry buildings prior to the value enhancement [2].

**Table 3** shows the soil criteria and masonry modelling for different buildings studied. It is taken as a criterion modelling by finite elements for walls using the type plate element of four or eight nodes. Drucker-Prager model has been used for the simulation of material failure [15]. The foundation is modelled by elastic springs, or the soil is modelled directly, considering its rigidity (elastic), since in this type of structure soil stiffness plays a fundamental role. For the roof structure, which is generally flexible, main resistance elements such as trusses or girders (ridges, etc.) are modelled, distributing loads to these elements. The seismic action is determined by applying the methods established by the regulations as proportional forces to the mass of each node of the finite element mesh [17].


#### **Table 1.**

*Data on the buildings studied.*


**Table 2.**

**67**

*Historic Masonry*

Modelling structure

Type of proposed intervention

**Table 3.**

*DOI: http://dx.doi.org/10.5772/intechopen.87127*

Elastic Midlin theory Plaxis Bv

**Ruins, Capital**

Mohr-Coulomb elastic theory Plaxis Bv

earthquake IV MM

Reversible (temporary propping) until the final consolidation project

**Evaluated Saint Francis** 

Estimate safety It supports

Modelling soil Triangle 15 nodes

**8. Repair, rehabilitation and retrofit of historic masonry**

respect to URM that suffered damage and collapse [3].

to achieve sufficient safety.

*Modelling and type of intervention.*

engineering [17, 18].

groups could be:

A large number of historical structures do not meet safety requirements because today's requirements are more demanding than those at the time of construction and because many years have passed by since their construction and structural safety has deteriorated due to use and time. To bring these historic buildings to a level of safety standards today, it is necessary to adapt its structure. However, his

**Mitre School, Capital**

Eight nodes isoparametric nonlinear Abaqus SAP2000 linear retrofit

>80% of the original

Reversible (outer metal reinforcement chained) Irreversible in foundation

Present status Executed Executed Proposed Executed

Triangle 15 nodes Mohr-Coulomb elastic theory Plaxis Bv

**Giol Chalet, Maipú**

Linear masonry plates SAP2000 linear retrofit

>80% of the original

Irreversible (removal of corroded profiles) Without intervention foundation

**Fader House, Luján de Cuyo**

Interaction with Abaqus

Nonlinear model Drucker-Prager masonry Abaqus SAP2000 linear retrofit

>80% of the original

Reversible (outer metal reinforcement chained) Irreversible in foundation

Elastic theory Elastic theory

torical value may be lost due to intervention; therefore, new approaches are needed

The structural rehabilitation of historical buildings could be done by hiding those new structural elements or exposing them. Sometimes, the exhibition of new struc

ent restoration charts (Venice, Athens, etc.), and the task is a challenge of structural

• Interventions to obtain better global response of the building (in case of build

The strengthening techniques depend on the building response to the earth

quake. Different response leads to different strengthening methods. Three main

ing box type behaviour and a prevailing in-plane response, **Figure 11**

The San Fernando, California, earthquake of 1971 demonstrated that the adaptation of the parapets to avoid their fall was effective. The 1994 Northridge, California, earthquake showed little damage to historic reinforced masonry with

tural elements is preferred because alterations of this type may be reversible; in the future they can be changed without losing the historical character of the building [17]. The decision to hide or expose structural elements is complex, and there is to be a consensus with the preservation professionals who are participants of the project. In high seismic-risk area, it is difficult to strictly follow the principles of the differ






)

*Characteristics of previous interventions, masonry and existing pathologies.*


#### **Table 3.**

*Heritage*

**66**

**Evaluated**

Valid

1941: Put in value

Maintenance Ruins Park and

archaeological exploration

contributions

from different

epochs

Masonry type

Masonry handmade ceramic solid

Handmade ceramic solid 0.55 m (head

Handmade ceramic solid 0.30 m (head)

with metal profiles on walls

rope)

Slab of masonry and metal beams

Good constructive technique

mortars with different types of

and rope)

Good constructive technique

bonding Variable thicknesses

Main problems

1861: Destruction by earthquake

Cracking cut eardrums 1985

Expansion mortar corrosion of wires

Cracking of supporting structures, mixtures

of materials, lack of soil bearing capacity

Contributions of soil moisture

Problems in storm drains

Masonry deterioration by weathering,

efflorescence and presence of salts

Problems with gardens

and profiles on walls

Reinforcement corrosion losses in

storm drains

Contributions of soil moisture plumbing

losses

Presence of soluble salts

earthquake

Separation facade 2006 earthquake

Lack of perimeter chains

Settlement arches for lack of

foundation bearing capacity

Water drainage and sewers problems

Efflorescence and soluble salts

High (alluvial soil)

Mendoza earthquake of 1917 and later

Lack of maintenance

High (alluvial soil)

High (alluvial soil)

Several earthquakes

Interventions

Lack of maintenance

Deterioration by weathering

detected,

damages and

(capillarity)

Cracking in critical areas

Imposition of vegetation

durability

Regional

High (alluvial soil)

seismic risk

Causes of

Mendoza earthquake of 1861

structural

and later

damage

**Table 2.**

*Characteristics of previous interventions, masonry and existing pathologies.*

**Saint Francis Ruins, Capital**

**Mitre School,**

**Giol Chalet, Maipú**

Different uses over time (bank deposit,

Summer house

1949: Put in value as a museum

Subsequent updates of aesthetic value

Handmade ceramic solid 0.55 m (head and

file, housing)

**Fader House, Luján de Cuyo**

**Capital**

Maintenance (paint, flooring)

1955: Replacement of floating floors

1964: Reinforcing bases

*Modelling and type of intervention.*
