Flanged deep beams - Reinforced Concrete Deep Beams - page 115

5 Flanged deep beams

H.SOLANKI and A.GOGATE, Smally Wellford and Nalven
Inc., and Gogate Engineers, USA

Notation

a shear span l span length

A s area of tension reinforcement l n clear span length, measured face to

face of supports A v area of shear reinforcement within

a spacing s v

M u factored moment

A vh area of horizontal shear reinforce-

ment within a spacing s h

s h spacing of horizontal shear rein-

forcement

b width of beam s v spacing of vertical shear reinforce-

ment

b w width of beam web

c clear shear span V c nominal shear strength provided

by concrete; vertical shear
force

d effective depth

f cu concrete characteristic cube

strength

V s nominal shear strength provided

by shear reinforcement f y reinforcement yield strength or

characteristic strength

V u factored shear force

f' c concrete cylinder compressive

strength

z lever-arm distance

r w steel ratio; web steel ratio

h height of beam f strength reduction factor

h f thickness of flange

5.1 Introduction

A beam having a span to depth ratio less than about 5 may be classified as a
deep beam. Deep beams occur as transfer girders at the lower levels in tall
buildings, offshore gravity type structures, foundations and so on ( Figures
5.1 and 5.2) . The main design recommendations for deep beams have been
summarised in Chapter 1. This chapter covers the behaviour of reinforced
concrete flanged deep beams. Flanged beams are usually deep and consist of
a thin web ( Figure 5.3) . The application of flanged deep beams normally
may not be apparent in ordinary reinforced concrete structures but they are
for instance a major structural component in the foundation of offshore
gravity type structures and in the horizontal and vertical diaphragms used to
transmit wind forces in tall buildings. Little published information is
available on the behaviour of reinforced concrete flanged deep beams.