Ground Motions and Structures - Earthquake Engineering for Structural Design - page 334

334 Earthquake Engineering for Structural Design

(b)

Figure 8.33 Structural residual resistance by: (a) Alternative path approach;
(b) Catenary effect (Gioncu, 2007, after Mendis and Ngo, 2003, Astaneh-Asl, 2003)

8.4DEVELOPMENTOFMATERIALSFORSEISMIC-RESISTANT
STRUCTURES

The need to erect structures in seismic areas has led to the development of some
particular typologies. Earthquake-resistant structures must absorb and dissipate
induced motion through a combination of damping and inelastic deformations.
Therefore, there are two main determinant factors for a good response: materials
having satisfactory ductility and structural systems able to fructify this ductility in a
dissipative system. The developments of structural systems will be discussed in the
next section. The main materials used in seismic areas are masonry, concrete and steel.

8.4.1Masonry

The seismic vulnerability of traditional masonry buildings is well recognized. In order
to improve their behavior, the reinforced masonry construction system has been
introduced in the modern masonry buildings. The most common type, used as seismic-
resistant wall, is the reinforced grouted cavity masonry , which consists of two parallel
masonry panels, which are built at a given distance (Fig. 8.34a). Inside of the cavity
between the two panels, a mesh of vertical and horizontal steel rebars is located and
then filled with cast concrete. The second type is the confined masonry , (Fig. 8.34b)
which is a masonry panel confined on all four sides by reinforced concrete members,
the horizontal ones being bond-beams and vertical members called tie-columns. In
order to achieve an effective wall confinement, the tie-columns must be located at all
corner joints and wall intersections.