275
“
There is a covered passage above this wall composed by col-
umns made of jasper and other marbles. Over this, there is an
uncovered passage delimited by parapets. From both of them,
not only a great part of the city, but also some lands and these
gardens can be seen”
19 —figure 13—.
4. INTERVENTION
In any case, the recovery of the uncovered passage could only be car-
ried out once the structural intervention had been performed. The
framework separating the covered and uncovered passages also sup-
ports the upper passage. This is the reason why the first decision
of the project was necessarily connected with solving the problems
suffered by this framework.
Some factors made us lean towards the complete replacement of the
framework. Those factors were, among others, the poor state of the
metal elements, the improper working of the gargoyles, the age of
walls and parapets or the fact that in the western wall of the façade
dampness constantly showed up among the joints of its blocks of
porous stone. The demolition of the last section of the gallery was
also included in this decision. It was finally replaced by prefabricated
joists in 1991 so that the constructive solution did not suppose the
appearance of an element imposing a height level for the develop-
ment of the rest of the gallery.
Demolitions and previous tasks
Following the information about the framework given by the pre-
vious study, the poor state of the wooden beams and the concern
provoked by the earthquake of Lisbon, which led to put supporting
braces among walls, we had to perform an intervention without dam-
aging those braces. The inner emptying could cause the falling of the
parapets, so, given the rarity of the western façade of the
Galería del
Grutesco
, fork-shaped braces were design and built and they were
placed by the walls with the adequate precautions not to harm the
opus rusticum
. During the intervention, they were called “goal”. They
were composed by a double reinforced metallic tubular structure and
were placed so that they could support the two parapets that were on
the opposite side of the part of framework that was going to be demol-
ished. The demolition was carried out by sections of not more than
5 meters in order not to leave a large whole in the framework at any
moment. As the demolition started in autumn, the fork-shaped braces
also worked as an umbrella really useful to work during rainy days.
The first section started to be demolished from its northern side
when the crane and the areas for stockpiles were placed on the
eastern side of the
Puerta del Privilegio
. The look shown by the first
beams confirmed our worst suspicions and transformed the deci-
sion taken into the best option, replacing the whole framework.
This included removing any metal element that could get rusty and
harm the walls. We had to remove as well the built-in extremes of
the beams. The two types of moorings found between the beam
extreme and the wall demonstrate the historic concern about the
placement of supporting braces: threaded rod or in-and-out screws,
both of themmeasuring twenty centimeters long.
Throughout the gallery, there are also approximately fifty square
crosspieces of solid iron that are similar to the ones used in 1759 after
the earthquake. The moorings of these crosspieces to the walls could
be: twenty-centimeter-long hook-shaped prolongation or clamp with
in-and-out screw, the most harmful for the parapets. Removing the
crosspieces and some beams was a slow and thorough work, as many
of themwere deeply built-in, practically until the façade—figure 14—.
Structure
In order to replace the framework, we used collaborating steel plates,
a decision taken by consensus with the Board of Trustees of the
Real
Alcázar
. Despite the fact that it was not a traditional structural solu-
tion, it really met the conditioning requirements of the
Galería
del
Grutesco
:
• Durability, as these collaborating steel plates are made of gal-
vanized steel, offering a higher protection against damp than
wooden or other metal elements.
• Rapidity and ease of assembly, in comparison with reinforced
concrete, the little light admitted in the gallery allowed the
framework assembly without needing propping-up.
• Less thickness (six cm of ribbed sheet + six cm of compression
layer), which enabled to readjust the framework level to a proper
height so that gargoyles could perform their function again. In
addition, the recovery of the uncovered passage implied the
removal of all the wirings running through the parapets of the
gallery. The reduction of the framework thickness would make it
possible to build a false ceiling through which the wirings would
run without reducing the height of the inferior passage.
On a technical level, the solution given for the sheet framework was
adapted to the three situations produced in the gallery: the general
view, the southern end and the two towers. Once the supporting
function of the metal elements from the beginning of the twenti-
eth century and of the solid-iron crosspieces was ended, metal con-
nectors were placed between the collaborating steel plates and the
lateral walls in order to reinforce the braces, a supporting element
that would complement the new framework. This was built by using
HILTI HAS M10 thread bars with HY-30E resin. They were located
every thirty cm in both walls —figure 15—.
Adaptation
After the assembly of the framework and the building of the roof by fol-
lowing a traditional method, which included thermal insulation, water-
proofing sheets and ceramic flooring, the remaining tasks already kept a
certain relation with the recovery of the uncovered passage.
In fact, we chose to use handmade ceramic tiles, so that the flat roof
could get back a color and texture that had faded. In contrast with the
homogeneity of industrial elements, tiles baked in a wood-fired oven
have different tonalities according to the position of the tile in the oven.
The general disposition of the flooring was in herringbone pattern
in the longitudinal direction of the passage. On the sides, the ir-
regularities of the walls were solved by using lateral bands made of
half pieces. This disposition only changes in the interior of the view-
points, placing the pieces transversely and without borders.
Before the construction of the roof and it ceramic finish, we had to
repair the wall parameters, which were really deteriorated because
of water inlets. As the inner face of the parapets was been perforat-
ed, we discovered tapia layers and different types of wrought stones.
