diagnostic of the colonial structure “palacio del segundo cabo” in havana, cuba

8/13/2019 Diagnostic of the colonial structure Palacio del Segundo Cabo in Havana, Cuba

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Geotechnical Engineering for the Preservation of Monuments and Historic Sites Bilotta, Flora, Lirer & Viggiani (eds)

2013 Taylor & Francis Group, London, ISBN 978-1-138-00055-1

Diagnostic of the colonial structure Palacio del Segundo Caboin Havana, Cuba

S. Figueredo & Y. GmezINVESCONS, Havana, Cuba

R. Lorenzo, J. de la Rosa & R.P. da CunhaUniversity of Brasilia, Brasilia, Brazil

ABSTRACT: The Palacio del Segundo Cabo, was built at the end of 1790 in Havana, Cuba and hasundergone several modifications. In recent years he has begun to have sharp deterioration in its structure.

An investigation was conducted to determine the causes of the observed damages. The work was focusedon analyzing the characteristics of the materials, monitoring and determining the structure of settlementsoccurred in the 222 years of existence. It was found that the main cause of the damage is related to theheterogeneity of the soil and foundation support. As a result the authors recommend using a micropileunderpinning. The assumptions were validated by an analysis of the behavior of the structure based onthe finite element method.

- 19631965. Office of the deputy ministry ofeconomy of the Ministry of Culture.

- 19702005. Cuban Book Institute.

Since its early decades some damagehas appeared throughout the structure, resulting inimbalances that have been intensifying in recent years,something that prompted the Office of Consulting &Design of the National Applied Research, INVES-CONS to conduct an investigation. The work wasconducted in 2011 and it was focused on the identifi-cation of major cracks and weaknesses in the struc-ture, the characterization of materials involved andthe evaluation of the causes of the deterioration. Thework also focused on the structural security takinginto account the existing damage from the existingto finally establish strategies for a complete repair.

1 INTRODUCTION

Important building were constructed in Havanaduring 1770, among the main plans was a civiccenter where the political and administrative activ-ities of the colony gathered together. The Plaza deArmas, as the square was finally named, wouldhouse important buildings, among which were theinfantry barracks, the customs, a municipal housewith the Governor Generals residence, and thePost Office Management, which a few years laterbecame the Palacio del Segundo Cabo.

The Palacio del Segundo Cabo is a monumen-tal building with Protection Grade I and, becauseof its antiquity and majesty is one of the mainbuildings of Old Havana. The edifice is locatedon the corner of Tacon and Orreily Sts and in its

222 years of existence has hosted dissimilar insti-tutions undergoing major expansions, structuralmodifications and changes of use. Among themost important are the following:

- 17901828. Post Office Management.- 18281900. Office of the General Sub-Inspection

of the Army.- 19021911. Senate headquarters.- 1929. Supreme Court headquarters.- 19561960. Academies of History of Cuba,

Geography, Fine Arts and Spanish Language.- 19601963. Academy of Sciences of Cuba.

Figure 1. Perspective of Palacio del Segundo Cabo in1790.


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2 DEVELOPMENT

In order to achieve the proposed objectives of theresearch, a group of tasks was carried out as partof a methodological approach that brings togetherthe following activities:

- Study of the historical background, typologiesand the employed construction techniques.

- Performing architectural, structural and patho-logical surveys, to reproduce the geometry ofthe studied phenomenon with a high degree ofaccuracy.

- Location, classification and quantification ofdamages.

- Diagnostic and physical mechanic characteriza-tion of the materials to establish the parametersof constitutive models to be used to simulates

their actual behavior.- Implementation of instrumentation systems formeasuring the activity of the cracks and valida-tion of numerical models.

- Analysis and evaluation of the structural behav-ior to validate the hypothesis and define theengineering solutions for the total repair of theproperty.

2.1 Surveying

A Geometric leveling was carried out to deter-mine the difference of levels on the perimeter ofthe building, taking as reference the lines of thefacades decorative elements and an arbitrarycoordinate system. The results indicated differ-ences between 0.038 m and 0.154 m, and the mostsignificant were located on the facade on Tacon St,as shown in Figure 2.

It is considered that the slopes may have beencaused by two fundamental elements, imperfec-tions during its construction and the settlementsof the structure due to its own weight.

Taking into account the geometric dimensionsof the building and the geotechnical characteristics

of the materials on which it rests, it is estimatedthat these settlements could occur during the con-struction of the building.

In the same way, the subsidence of each facadewas determined, with values ranging from 30 to130 mm, with the highest values on Tacon St onceagain.

2.2 Structures survey

The original structure consists of load-bearingwalls built of stones and rough stones with thick-

nesses ranging from 700 to 900 mm in the perimeterwalls and between 500 and 800 mm in the interiors.The most common modifications are summarized

in closing spaces, construction of partition wallsmade of bricks and the replacement of floors and

roofs made of wooden beams with reinforced sipo-rex type slabs. However, major structural changestook place in the early twentieth century in order

Figure 2. Results of the geometric leveling on theground floor.

Figure 3. Subsidence on Orreily St seen fromTacon St.

Figure 4. Subsidence of facades of Tacon St and theEast side, seen from Orreily St.


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to convert the building into the headquarters of the

National Senate. At that time, the first two bays onthe first floor were drastically changed and a domewas built in the center of the main hall.

2.3 Pathological survey

Based on the survey prepared by the participants inthe first workshop given by the Association Sisto-Mastrodicasa along with the San Geronimo Uni-versity in Havana, an update was made to locate,classify and quantify the damages in the palace, sothat problems can be identified to create an inven-

tory of damage in each case.The detected damages in the structure are largelyof structural origin, and then some damages asresult of the degradation of the materials. For abetter understanding the injuries are classifiedaccording to their origin into three categories:

- Pathologies of the materials These damages are caused by the degradation

of the constituent materials. The factors affect-ing them are mainly due to the environment andaging. These injuries usually do not have struc-tural implications but in the aesthetic and they

are seen through cracks, places where the plasteror panel has come off, efflorescence, corrosionof pipes and metal elements, presence of ter-mites and rot in the wood elements of the mez-zanines, etc.

- Nonstructural pathologies They are related to the environment and human

activity on the structure causing damages and itsdeterioration. In general terms there are damppatches, the presence of microorganisms andplants, leaks, etc.

- Structural pathologies These pathologies are associated with the struc-

tural behavior and were detected in virtually all

load bearing walls of the building and arches.These damages are manifested through cracks andfissures in walls and arches and facades collapse.

The most important crack cover a great part ofthe building, originating from the facade of Tacon

St, through the one of the East side, as shown inFigure 6.

It is again the facade of Tacon St the one withthe greatest damage, concentrated mainly in theextended area made during its construction andclose to Orreilys portal, as shown in Figure. 7.

In this facade major cracks go through the entirewall, in some cases with apertures of 30 mm evi-dencing previous repairs as is the case representedas (1) in Figure 7. Most of these cracks are mainlyassociated to the movement of the structure, col-lapses and the effect of overloading.

2.4 Instrumentation and monitoring of thestructure

A monitoring system was created which continu-ously registered the movement of cracks and theenvironmental temperature through vibrant wiressensors.

Figure 5. Palacio del Segundo Cabo after its restorationat the beginning of the twentieth century.

Figure 6. Scheme of the main crack.

Figure 7. Pathological survey. Facade of Tacon St.cracks detail (1).


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This sensor allowed the assessment of the

cracking activity in the building, which has laterbeen served as a basis to calibrate the numericalmodels.

It was found that all sensors showed a signifi-cant relationship between the temperature andthe movement of the cracks. The results corrobo-rated the instrumented cracking activity. 70% ofthe 13 installed sensors showed a slight tendencyto remain stable or closed, while 30% tended tocontinue the opening process. The latter sensorswere located in the main cracks represented infigure 6.

3 MODELING THE PROBLEM

To assess the structural behavior of the Palaciodel Segundo Cabo and the possible causes behindthe pathological phenomena in the structure andits influence on structural safety, the authorsuse mathematical simulation tools based on theFinite Element Method. The interpretation ofresults corroborates the hypotheses based ontheir correlation with the fissure system in the

facility.Also the behavior of the recommended solu-tions to new conditions can be predicted.

The finite element models are adjusted using thedata obtained from the work field. Because of this,the involve aspects in the modeling process (geom-etry, applied loads, materials and support condi-tions) are well calibrated.

As a result a three-dimensional model of thestructure and another of the soil are created toestimate the settlements occurred in each of theload phases of the building. The combinationof both models guaranteed the analysis ofsoil-structure interaction with the possibility oftaking into account the influence of the founda-tion movements in the structural behavior.

3.1 Geometry modeling

Taking into account the surveys conducted byGEOCUBA (GeoCuba, 2009) and structural sur-veys made by the authors of this work, the lattercreated a three-dimensional model of the struc-

ture using bi-dimensional elements Shell style.With the use of the digital model the authorsreproduced with great accuracy the geometry ofthe building.

The foundation is very variable, both from thegeometrical point of view and the materials usedin its construction. In the model this is taken intoaccount since the foundation width varies between1.10 m and 1.30 m. The foundation depth varies from1.40 m to almost 1.60 m on Tacon Street. It rangesbetween 2.95 m and 3.25 on Orreily Street andbetween 3.75 m and 4.00 m for the eastern faade.

On the north side it is between 1.40 m and 2.50 m andthe extended area constructed in the early twentiethcentury directly rests on the wall of the moat.

3.2 Materials modeling

The characterization of the materials of a structureof this type is very complex. Ashlars walls have avery large variability throughout the structure;therefore different areas were identified based ondrilling resistance and 7 samples taken in the walls.

The mechanical property values are taken fromtests performed to samples of the ashlars and stud-ies conducted to similar buildings on Lombillo(2010). It is considered that ashlars have a perfectelasto-plastic behavior. The mechanical propertiesof the ashlars wall are show in Table 1.

As for the different soil layers, they are consideredto have a behavior based on the Mohr-Coulombcriteria and the properties used are those obtainedby the Geological Engineer Study, conducted by theUICHavana of the National Body of AppliedResearches. This study identified the followinggeological-engineer elements.

Figure 9. Geometric pattern.

Figure 8. Installed sensors and measurement systemused.


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- Element # 1: Heterogeneous fill with low to

medium compactness, consisting of a sandymaterial with shells, glass, pottery and coal. Thereare also calcareous gravels with irregular shapeand size and limestone fragments, sometimes itis muddy. The gravel is dark brown to yellowishbrown, sometimes it is dark gray to black, some-times gray-white to yellow with red intercalations.Its thickness varies from 1.95 m to 4.00 m.

- Element # 2: Sandy and muddy calcareous gravelwrapped in a muddy and clayey matrix of low tohigh compactness and colored in yellowish tobluish white. Fragments ranging from 12 cm,

although in some places they are 7 cm withangular shape. The power of this element variesfrom 2.40 m to 3.95 m.

- Element # 3: Organogeneous limestone inyellowish white color with red, orange and greenstreaks, soft resistance, porous, with cavities upto 2 cm deep and stained with brown clay. It isseen from between 4.80 m and 6.80 m minimumdepth and between 1.70 m and 3.50 m thick.

- Element # 4: Half-compact clayey sand withsmall limestone fragments in yellowish whitecolor. It only appears in Cove 2, of 7.00 m to8.75 m followed by limestone with 1.75 m thick.The fact of been below the limestone with solittle thickness no physical nor mechanicalproperties were determined.

- Element # 5: Plastic clay with firm to hardconsistency, yellowish brown color with yellow,red and green streaks. This material appears inall vertical coves of 7.35 m from 9.60 m.

The water table was found in all the coves drilled

to a depth between 3.55 m and 4.90 m, while thewater level in the moat of the Castillo de la RealFuerzais approximately 4.00 m above the groundlevel.

3.3 Loads modeling

All the different load states and combinations forwhich the structure has passed through have beenconsidered. The authors have also analyzed theloads proposed in the project based on the new useof the facilities.

It was considered the following five load steps:- Weight of the structure (PP).- Permanent load of filling. (Roof =35 cm, First

Floor =30 cm, Ground floor =15 cm) (CP).- Use loading (Roof with rainwater downpipes;

Mezzanines estimated depending on use) (CU).- Daily thermal variation load (CT).- Differential settlements (CD).

Environmental loads are not taken into accountin the analysis as the authors considered it has anegligible influence on this type of rigid structure.

3.4 Load combinations

The following table defines the most unfavorablecombinations that may arise during the life of thestructure:

3.5 Modeling the boundary conditions

In the structural model it is considered that theunion among the different walls is continuous.

The slabs are modeled to work supported ontwo edges and to be articulated at their junctions

with the walls.The support of the walls on the ground has been

considered as articulated because of the under-designed foundation underneath, which is unableto transmit moments to the soil.

Table 1. Mechanical properties adopted for the walls.

d(kN/m3)

u(MPa)

Esec(MPa)

e(MPa)

16.00 1.56 3488 0.50 0.33

d: specific weight.u: ultimate compression strength.Esec: secant modulus of deformation.e: stress elastic limit.

Table 2. Physical-mechanical properties of soils involvedin the behavior of the foundations.

Description

d(kN/m3)

cu(kPa)

()

E(kPa)

Rc(MPa)

Heterogeneousfilling

17.00 0 25 4500

Calcareousgravel

18.00 0 28 12500

Organogeneouslimestone

16.68 80 31 160000 9.74

Clayey sand 20.00 50 25 5000

Plastic clay 17.00 80 0 3000

cu: undrained shear resistance.: internal friction angle.E: modulus of deformation.Rc: simple compression strength.

Table 3. Most critical load combinations.

# Loads combination Limits

1 1.2 PP + 1.2 CP ULS

2 1.2 PP +1.2 CP +1.6 CU ULS

3 1.0 PP +1.0 CP +1.0 CU ULS4 1.2 PP +1.2 CT ULS

5 1.0 PP +1.0 CD SLS


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In the soil model, the assumed boundaries wereplaced at a reasonable distance from the founda-tion to avoid any influence in its behavior.

4 SETTLEMENTS ESTIMATION

Authors estimated settlements for three phases ofanalysis, whose results are shown below:

- First stage

The stresses generated in the soil by the weightand all permanents loads of the building. Underthis state there are settlements that reach between3 and 13 cm. It is considered that these depres-sions are not the cause of the damage observedin the building, as the materials of the groundand the foundation have the property of accom-

modating very quickly, almost instantly. For thisreason the authors state that some adjustmentmust have occurred during the construction ofthe building and its magnitudes are consistentwith the results of the geometric leveling previ-ously done.

- Second phase

Based on the state of stresses imposed in the firstphase other stresses generated by the temporalloads have acted on the ground, during the vari-ous uses to which the building has been subjected.This analysis allows the calculation of the abso-lute and differential settlements that caused thecurrent state of the building, which are estimatedat a magnitude ranging between 0.16 and 0.64 cm.Clearly, the magnitudes are very small, but theinfluence of these movements in the behavior ofthe superstructure causes tension states whichexceed the tensile strength of the wall.

- Third phase

Because of the new use of the facilities, newtemporary loads will arise. The stresses gener-ated by these last ones at the foundation base areimposed to the ground.

The behavior is similar to the second phase,therefore it is considered that no significantchanges in the behavior of the foundationsshould be introduced.

It is considered that these differential settlementsare due to the great heterogeneity existing in boththe foundation structure and the soil support.

5 INTERPRETATION OF THE RESULTS

Based on these studies, the authors elaborated sev-

eral hypotheses regarding the main causes that ledto cracks appearing in the building.

The stresses states generated in each load com-binations may be calculated with the use of numer-ical modelling.

As a result it could be infered the direction ofthe fissures and thus verified if they match thosein the facilities. This would confirm the hypothesesregarding the causes of the appearance of cracksor fissures.

Hypothesis 1. The main cracks in the facade onTacon St (1) (Fig. 7) are generated by the combi-

nation of two deteriorating effects: the applicationand distribution of the loads and the occurrence ofsmall quantities of displacement as a result of theeffect of live loads of long duration.

The formation of this crack is complex, it had tobe analyzed in two steps to find the causes of it.

The main stresses appearing in the facade whenanalyzing the complete combination of gravityloads, which is permanents loads plus live loads,cause main tensile stresses coinciding with the areawhere the crack appears on the parapet.

The values of these tensile stresses are capableof exceeding the strength of the material the wallit is made of.

Figure 10. Estimated settlements for long term useloads. (Units 10-3 m).

Figure 11. Differential settlements imposed to thestructure.


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The development of the crack to the corner ofthe window has been caused by another phenom-enon. In assessing the response of the structureto the differential settlements that have been cal-culated for the live load, tensile stress states arisein the area near the window with a direction thatcould cause cracks like this one until it joins the fis-sures created by the effect of load distribution.

Regarding this crack it could be concluded thatit has been caused by two phenomena, i.e., thechange in the loads direction and differential settle-ments. Hence, corroborating the stated hypothesis.

6 RESEARCH FINDINGS

6.1 Regarding the structural pathologies

- The causes that have led to the state of crack-ing of the structure (walls) are directly linked tothree factors.

- The heterogeneity of the foundation and thesupporting soil.

- The application procedure and distribution ofthe loads on floors and roof.

- The inadequate geometry of the arches and lackof rigidity in the supports.- The cracks are associated mainly to three

causes.- High slenderness of the walls.- Lack of bracing in the elements of the mezza-

nine and the roof.- Pressure of the arcs.

6.2 Regarding the structural behaviour

- Despite deterioration levels of the structure andthe eccentricity of the load due to the slender-ness of the walls, the building meets the safetyrequirements in the ultimate limit state for theevaluated load combinations.

- In general terms, there is a perfect relationshipbetween the variation of the temperature andthe opening and closing cycles of the cracks andfissures.

- The activity of the implemented cracks were cor-roborated. 70% of the sensors showed a slighttendency to remain stable or closed, while 30%tended to continue opening.

7 RESEARCH RECOMMENDATIONS

The rehabilitation work should be focused on:

- Remove the heterogeneity of the foundationand the supporting soil by improving it with anunderpinning.

- Strengthen the structure of the arcs through ten-

sioners that eliminate the horizontal thrusts theygenerate.

- Restitution of the structural continuity in thecracked walls with metal staples.

- Implement conventional treatments with injec-tions to the remaining cracks in walls andarches.

8 MITIGATION STRATEGIES

Key aspects are focused on underpinning the foun-

dation with micropiles based on the followingcriteria:

- Respect the original dimensions of the structure.- Eliminate the causes of deterioration.- Structural efficiency.- Optimal structural safety-cost relation.- Proper execution of the solution.- Geotechnical design of the micropiles.

The geotechnical design of micropiles has beenaddressed by several researchers, among whichLizzi (1985) and Bustamante (1986) stand out.

These authors developed calculation methods thatare widely used. It is also common to consider thedesign methods developed for piles.

From the physical point of view, the ultimatebearing capacity of a micropile will depend ontwo key factors: the friction generated betweenthe ground and the shaft and the sinking of thetip. However, the influence of the tip is usuallyneglected due to its small diameter and above allbecause in many cases it can not develop due to itsslenderness.

Its behaviour is similar to the piles and thereforehas the same design uncertainties. When determin-ing the load capacity through different methodsa great variability is achieved, so that their designneeds to be adjusted by loading tests on the job site.

Figure 12. Main tensile stresses on Tacon St caused bydifferential settlements.


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The execution technique of the micropiles itselfgenerates a difference between the diameter of theperforation (nominal diameter) and the diameter ofthe micropiles performed after the injection (calcula-tion diameter). This calculation diameter is estimatedthrough a coefficient that takes into account the typeof soil and increase of the nominal diameter.

The following table summarizes the results ofthe geotechnical design of micropiles by differentmethods. It is considered a nominal diameter or

drill diameters of 100 mm.The value of working capacity does not take into

account the Caquot-Kerisel method (Caquot-Kerisel,1953) as it was considered abnormal. This is in agreewith the results presented in Lyamin et. al. (2007)about the higher values obtained by this method.

8.1 Structural design of micropiles

The structural reinforcement of the micropiles is car-ried out with a metal pipe of TM-70 60.3 5.5 mmplaced inside the bore. The adhesion between the

micropiles and the head is assured with bars weldedto the head pipe.

8.1.1 Distribution of micropilesBased on the structural analysis, the solicita-tions of the foundation for the load combinationPP +CP+CU were determined and based on thesevalues there were established four working rangesfor the micropiles distribution. In each of the wallspart of the supporting system of the building wasestablished.

It was adopted a length of 10.50 m for micropilesin order to reduce the amount of perforations.

Micropiles will be place in quincunx, it means,alternately on both sides of the wall, as an under-pinning recuperation process.

Table 4. Load capacity for nominal diameter of 100 mm.

Designmethods

*(mm)

**(mm)

G.S.F***

Qu(t)

Qt(t)

, 100 1.5 150 3 38.0 12.6

C-, , 100 1.5 150 3 20.1 6.7Caquot-

Kerisel100 1.5 150 3 120.0 40.2

Lizzi (1985) 100 1.5 150 3 63.6 21.2

Bustamante(1996)

100 1.5 150 2 25.0 12.4

M.E.F 100 1.5 150 1.6 34.0 21.0

Working load (t) 15.00

* Nominal diameter.** Calculation diameter.*** Global safety factor.Qt: design load capacity.

Qu: ultimate load capacy.

Figure 13. Schematic section of the micropiles.

Figure 14. Load distribution in the foundation leveland micropiles spacing.

Figure 15. Underpin scheme.


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The load transfer between the wall and themicropiles is expected to be through a transitionelement or head with a level of rigidity to ensureuniform function of the micropiles. The heads areinterconnected by means of a metal tensor thatgoes through the wall and confines it in such a waythat the load on the wall can be distributed to theheads and on to the micropiles.

9 CONCLUSIONS

The evaluations of old story building needs thecombinations of different techniques as instru-mentations, numerical analysis and constructiontechnology. In this study the analysis of differentpossibilities and hypothesis of the actual state ofdeterioration of a century building was done.

The current conditions of the Palacio del SegundoCabo urges its underpinning with 429 micropilesof 100 mm nominal diameter and 10.50 m depth toensure the elimination of the heterogeneity of thefoundation and supporting soil.

ACKNOWLEDGEMENTS

The authors acknowledge the fruitful cooperationbetween Cujae and Braslia Universities in regardto studying numerical models to be applied to prob-

lems similar to the one referenced herein, and alsothank the Ministry from Cuba to allow the study,analysis and presentation of this case history.

REFERENCES

Bustamante, M. 1986. A method for calculating theanchors and injected micropiles. CEDEX No. 174.May-June and July-August, 323.

Caquot, A. & Kerisel, J. (1953). Sur le terme de surface

dans le calcul des fondations en milieu pulverent.Proc. 3rd Int. Conf. Soil Mech. Found. Engng, Zurich1, 336337.

GeoCuba. 2009. Levantamiento Topogrfico del Palaciodel 2do. Cabo. Havana. p. 20.

Group of authors. 2010. We save the salvageableAssoci-azione Sisto Mastrodicasa and Office of the Historianof Havana City. Havana, p. 25.

Lizzi, F. 1985. Paliradice (root piles) and reticulated pal-iradice, Micropiling Cap. 4 and 5 of underpinning.Ed S. Thorburn and J.F. HUTCHINSON Surrey Uni-versity Press Glascow and London. pp. 84151 and152159.

Lombillo, I. 2010. Theoretical and experimental research

on slightly destructive testing (MDT) used for in situmechanical characterization of the structures of builtheritage. Director: Luis M. Villegas. Doctoral Thesis,University of Cantabria. Santander.

Lyamin, A.V. et. al. (2007). Two and three-dimensionalbearing capacity of footings in sand. Gotechnique,57, No. 8, 647662.

Roman, M. 2003. Micropiles. Use in Underpinning.Conference on Underpinning Course II, Inclusions,Injections and Jet-Grouting STMR organized by theSchool of Civil Engineering of Valencia.

Salas, J., Jimenez, A., Just Alpaes, J.L. & Serrano, A.A.1981. Geotechnical and foundation. Tomo I to III.

2nd Edition. Editorial Rueda. Madrid.

diagnostic of the colonial structure “palacio del segundo cabo” in havana, cuba

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