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Structural Concrete - Hassoun

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20.5 Special Requirements in Design of Structures Subjected to Earthquake Loads 841<br />

20.5.2 Structures at High Seismic Risk: Special Reinforced <strong>Concrete</strong> <strong>Structural</strong> Walls<br />

and Coupling Beams (ACI Code, Section 18.10)<br />

A wall system is a structural system that provides support for all gravity loads and all lateral loads<br />

applied to the structure. A structural wall system is much stiffer than a frame system and its performance<br />

during an earthquake is better than the performance of the frame system.<br />

A structural wall should be properly designed to sustain all loads acting on it. Boundary<br />

elements of structural walls are the areas around the structural wall edges, as shown in Fig. 20.25,<br />

that are strengthen by the longitudinal and transverse reinforcement. Boundary elements increase<br />

the rigidity and strength of wall panels. The web reinforcement is anchored into the boundary<br />

elements.<br />

Figure 20.26 shows the elements of the wall with openings. The vertical wall segment<br />

bounded by two openings is called a pier. A horizontal wall section between the openings is called<br />

Web (wall)<br />

Boundary<br />

element<br />

w<br />

or<br />

Boundary<br />

element<br />

w<br />

Figure 20.25<br />

Boundary elements of structural wall.<br />

Pier<br />

Pier<br />

Coupling beam<br />

Pier<br />

Pier<br />

Pier<br />

Horizontal<br />

wall element<br />

Figure 20.26<br />

Elements of the wall with openings.

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