BENICARLO'S PALACE

Nicola (left) and the team during an essay with the penetrometer

This week we have visited a beatiful palace in Benicarlo (2 hours north from Valencia) from the 18^th Century. Fernando Vegas and Camillla Mileto, in my opinion, two of the greatest architects, recommended us to spend some time there because this week a team from the “Italian National Research Council” specialized in the non-destructive proof and assessment of the ancient timber would be there. We spent the whole day with the Italian team and watched and learnt how they perform their work, Maria Diodato, one of the members, was our host. I took some notes and pictures which are roughly summarized below.

Here the summary of how they asses the structural timber elements.

• First of all they measure the timber element, the cross section, the length, position, etc. Then they indentify the visual defects such as the knots in wood and their dimensions, the direction of the grain and so on. Nicola, the director of the team, taught me why the importance of the position of the knots in a structural element and how to know the effects of that.
• Before they start to use the “Penetrometer” they check the sound of the element hitting it with a rubber hammer (with the practice you can distinguish the sound of the sound timber, they say). In those places where the timber is internal damaged they use the penetrometer to calculate the resistant cross section of the element. The penetrometer consists in a “drill device” which pushes a kind of steel needle in the timber, the resistance of the needle to go through the timber gives a graphic where you can see the resistance of the cross section. With this device you can also evaluate the heads of the beams embedded in walls.
• Other device they use is the Hygrometer. They use it in the heads of the beams to see the inner humidity of the timber. Usually, if it is below of the 20% the timber is sound and if it is above is pretty easy to find fungi or xylophagous.

Using the Hygrometer at the embedded head of the joist

When you put all the results together you have to use the European Code to get, according to the corresponding table, the strength values for that type of wood. I remember that the American NDS has similar evaluations of the existing timber.

It is amazing how they do it, they checked every single wood element beams, joists, rafters, … They also have index cards of each one with the data they get.

Hall of the palace. Imperial stair at the background

The palace itself is gorgeous, it has an original eigtheen century kitchen, with decorative tiled walls, that is one of the best preserved in the Valencian Community and in Spain. See some pictures of the palace. I forgot to mention that the town of Benicarló has terrific beaches, weather and artichokes :)

Decorated tiled walls in the kitchen

Proportion?

Cast-iron beam

I am currently doing a research about a huge cast-iron construction placed in New York City in 1853. I have found the formulas used in that era to calculate the "bearing capacity" of the given beam. Two British Engineers who extensively publish their work pop, Hodgkinson and Fairbairn. Fairbairn focused in the Worought-Iron beams whereas Hodgkinson digged more in the cast-iron beams. Through their experiments, which generally consisted in bending differente shapes of beams under a known load, they usually stablished a constant "c" for each type of shape. This constant is obtained according to this formula, which is valid both for cast-iron and wrought-iron beams:

W=c*a*d / l

where:

W= max. weight

c = constant

a = area of the bottom flange

d = depth of the beam

The relation between the area of the bottom flange and the depth of the beam is directly proportional.The constant "c" is given in Tons/in2, thus this is quite similar of the yielding point in wrought iron or the breaking point in cast iron (because of its brittle fracture).

Cast iron is a strong material that performs excellent in compression but fails in tension and not mention in fireproofing. According to this, the I-Beams were shaped in bizarre flanges. Hodgkinson established a general formula to shape the cast-iron beams. According to his experiments the cast iron is 6 times stronger in compression than in tension, so it is logical using the same proportion for the flanges. Usually we find cast-iron beams where the bottom flange is between 6-6.5 times the area of the top flange.

I do not why but I really like these beams, maybe it is because each beam was cast for one place, building or purpose; with such detail hard to find nowadays.

Typical fracture of a cast-iron beam due to bending