Vertical loadbearing structures in solid construction

Cross-section concepts

The principle of solid construction exploits the physical phenomenon of gravity:

- mass - self-weight

- interlocking of wall elements: the "zip" principle (bricks, stones, hybrid forms)

- jointing mortar between wall elements: the "glue" principle, increasing the frictional resistance (adhesion) between the wall elements

- stability and load-carrying capacity: the "wide base, narrow top" principle; objective: optimised use of materials

Fig. 27: Base of wall approx. 6 to 7 m wide, top of wall 4 to 6 m; masonry "external walls" with rubble infill

Great Wall of China, c. 700-100 BC

Fig. 27: Base of wall approx. 6 to 7 m wide, top of wall 4 to 6 m; masonry "external walls" with rubble infill

Great Wall of China, c. 700-100 BC

Fig. 24: Tapered wall

Optimised cross-section

Fig. 23: Straight wall

Excessive cross-section

Fig. 24: Tapered wall

Optimised cross-section

Fig. 25 Stepped wall e.g. providing support for beams/ joists

Fig. 26: Sizing after Rondelet {Theoretical and Practical Treatise on the Art of Building Principally: the taller a free-standing wall, the wider its cross-section. Rule of the thumb for fi (average stability):

b = 1/10 h; built of rubble stones, factor approx. 1.75; ashlar stones, factor approx. 0.75

Ă®-standing brick walls subject to wind loads only

The form of the wall cross-section depends on various factors. The first critical factor is whether the wall is free-standing or whether it is braced or stiffened by other walls; this factor influences the width of the base. In any case, however, the cross-section will reduce with the height in order to optimise the use of materials because both the self-weight of the construction and the imposed loads resulting from the use of the construction gradually diminish further up the wall.

The variation in the cross-section can be either linear or stepped. It depends on the form of construction - with or without mortar, homogeneous or heterogeneous construction - and the building process (height of scaffold lifts), but is generally governed by utilisation considerations. For example, in a multistorey building it is sensible to step the cross-section at the level of the floors (and use the steps to support the floor beams/joists).

As the cost of labour in past decades has increased at a faster rate than the cost of materials, a building whose wall thickness decreases with the height is a rarity these days, with the exception of special structures such as retaining walls and dams. In the solid form of construction the larger wall loads of the lower storeys normally determine the size of the wall cross-section of all the upper storeys; this is especially true when we are stacking identical plan layouts one on top of the other.

Fig. 28: Multi-leaf wall with filling of loose, low-quality material (section)

Trulli - traditional solid stone buildings of southern Italy, Sovero (I)

Fig. 28: Multi-leaf wall with filling of loose, low-quality material (section)

Trulli - traditional solid stone buildings of southern Italy, Sovero (I)

40 cm

20 cm

00 m

12 cm

200 m

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