Flexural members - Reinforced Concrete with FRP Bars: Mechanics and Design - page 70

4.2 STRUCTURAL ANALYSIS

FRP RC slabs and beams are designed to resist the maximum effects induced
by the factored and the service loads. These maximum effects can be com-
puted based on the elastic or plastic structural analyses. When applicable,
approximate analysis methods are also available. Frame analysis to com-
pute maximum design bending moments and shear forces in concrete slabs
and beams is outside the scope of this topic.

4.2.1 Loading conditions for ultimate
and serviceability limit states
For the design of flexural members, the following load combinations are
generally considered [1,2]:

U = 1.2 D + 1.6 L (4.1)

U = 1.2 D + 1.6 ( L r or S or R ) + (1.0 L or 0.8 W ) (4.2)

U = 1.2 D + 1.6 W + 1.0 L + 0.5 ( L r or S or R ) (4.3)

where D is the dead load, L is the live load, L r is the roof live load, S is the
roof snow load, R is the roof rain load, and W is the roof wind load.
Traditionally, the load combinations for serviceability limit states use a
load factor of 1.0 on all service loads [1].

4.2.2 Concrete properties
Several models interpreting the behavior of concrete in compression are
available in the technical literature. The compressive stress-strain diagram
for normal strength concrete proposed by Todeschini, Bianchini, and
Kesler [3] is represented in Figure 4.1. f ′ c is the design concrete compressive

σ c

0.9 f c ´

ε c

ε cu

1.71 f c ´

E c