16. Balanced design refers to a design so
proportioned that the maximum stresses in
concrete (with strain of 0.003) and steel
(with strain of fy/Es) are 'reached
simultaneously once the ultimate load is
reached, causing them to fail
simultaneously.
17. Underreinforced design is a design in which
the steel reinforcement is lesser than what
is requited for balanced condition. If the
ultimate load is approached, the steel will
begin to yield although the compression
concrete is still understressed. If the load is
further increased, the steel will continue to
elongate, resulting in appreciable deflections
and large visible cracks in the tensile
concrete. Failure under this condition is
ductile and will give warning to the user of
the structure to decrease the load.
18. Overreinforced design is a design in which
the steel reinforcement is more than what is
required for balanced condition. If the beam
is overreinforced, the steel will not yield
before fai}ure. As the load is increased,
deflections are not noticeable although the
compression concrete is highly stressed, and
failure occurs suddenly without warning to
the user of the structure.
19. BALANCED STEEL RATIO (ρb)
In balanced. condition, the concrete and steel
yield simultaneously. In this condition, the
strain in concrete reached its maximum
usable value of 0.003 and the strain in steel is
fy/ Es, where Es = 200,000 MPa.
20. BALANCED STEEL RATIO (ρb)
By ratio and proportion iri the
triangle shown in Figure 2.2:
24. For statically determinate T-section with flange
in tension, the area As min , shall be equal to or
greater than the smaller value given either by:
or Eq. 2 - 16 with bw set equal to the width
of the flange .
31. According to Section 5.9.5 of NSCP,
minimum thickness stipulated in Table2.1
shall apply for one-way construction not
supporting O( attached to partitions or
other . construction likely to be damaged by
large deflections, unless computation of
deflection indicates a lesser thickness can
be used without adverse effects.
34. Section 5.8.3.3 of NSCP states that in lieu of frame
analysis, the following approximate moment and
shears are permitted for design of continuous
beams and one-way slabs (slabs reinforced to resist
flexural stresses in only one direction), provided:
(a) There are two or more spans,
(b) Spans are approximately equal, with the larger
of two adjacent spans not greater.than the shorter
by more than 20 percent,
(c) Loads are uniformly distributed,
(d) Unit live does not exceed three times unit dead
load, and
(e) Members are prismatic.