RC COLUMNS

Question 1

is something which carries load from bean and slab. Defined as the members that carries load mainly in compression.

Answer 1

Column

Question 2

In ______________, slab transfer loads directly to column and column transfer loads to footing

Answer 2

slab column

Question 3

columns are _______members of a structural frame intended to support the __________

Answer 3

vertical compression members

load-carrying beams

Question 4

columns support primarily ________ but usually also some bending moments

Answer 4

axial loads

Question 5

Structural column failure is of major significance in terms of economic as
well as ___________.

Answer 5

human loss

Question 6

What should be considered in column design to prevent failure?

Answer 6

Higher reserve strength than beams

Question 7

Higher reserve strength than beams

Answer 7

Compression failure

Question 8

What causes a column to fail in compression?

Answer 8

Axial stress exceeds its capacity

Question 9

At what strain does steel start yielding?

Answer 9

0.002

Question 10

What is the strain limit for concrete?

Answer 10

0.003

Question 11

Concrete columns are subjected to
_____________ in addition to the
axial forces due to the _________________ generated due to the
unbalance loads.

Answer 11

bending moments,

eccentric moment

Question 12

can be identified as
a failure of the design as we consider
the buckling effect in the design.

Answer 12

buckling failure

Question 13

What design factor is considered for buckling failure?

Answer 13

What design factor is considered for buckling failure?

Question 14

________loads in a structure are carried by
vertical elements such as columns and shear
walls.

Answer 14

lateral

Question 15

are generated by winds,
earthquake loads, from retaining structures,
etc.

Answer 15

Lateral loads

Question 16

The size of the columns is increased in the
direction of __________ to increase the _________
capacity.

Answer 16

shear

Question 17

In structural elements such as beams and columns, higher stresses
are generated near the __________. Lack of links in these areas causes
structural failures when cyclic loadings are applied.

Answer 17

connections

Question 18

Columns are torsionally rigid when they are
compared with the beam as they have
___________ around the section and links are
provided at _______________.

Answer 18

reinforcement around the section and links are
provided at closer spacings

Question 19

If the _________ exceeds the limiting values, columns
could be failed in torsion.

Answer 19

torque

Question 20

example for this failure is improperly treated
honeycomb in a column could lead
to a failure when the loads are
applied.

Answer 20

Failure due to Construction
Defects

Question 21

also called compression member or members subjected to axial load and bending

Answer 21

column

Question 22

columns tend to __________longitudinally and expand laterally due to ________

Answer 22

shortened
expand
poisson effect

Question 23

lateral restraint using closely spaced ties or spirals greatly ___________ the capacity of column

Answer 23

increased

Question 24

type of column failure when the cross section large as compared to its height. It fails due to “crushing” of column material

Answer 24

short column

Question 25

column failure when the cross section small as compared to its height. It fails due to buckling

Answer 25

long/slender column

Question 26

are principally of two types, classified according to the manner in which the longitudinal reinforcing bars are laterally supported.

Answer 26

Reinforced concrete columns

Question 27

usually of square or rectangular shape, is one in which the longitudinal reinforcing bars are held in position by separate lateral ties,

Answer 27

tied column,

Question 28

usually of circular or square shape, is one in which the longitudinal reinforcing bars are arranged in a circle and wrapped by a continuous closely spaced spiral,

Answer 28

spirally reinforced column,

Question 29

What is the strength reduction factor for spirally reinforced columns?

Answer 29

0.75

Question 30

What is the strength reduction factor for tied columns?

Answer 30

0.65

Question 31

What does the lower strength reduction factor for tied columns indicate?


Answer 31

Lower toughness compared to spirally reinforced columns

Question 32

is one that uses a structural steel shape, pipe, or tubing, with or without additional longitudinal bars.

Answer 32

composite column

Question 33

are the most commonly used because of lower construction costs,

Answer 33

tied columns

Question 34

__________or_____________ are also used where increased ductility is needed,

Answer 34

spirally bound rectangular or circular columns

Question 35

in a _________ the strength is governed by the strength of the materials and the geometry of the cross section

Answer 35

short column

Question 36

assumed acting at the center of the column

Answer 36

axially loaded columns

Question 37

will cause moment in the column

Answer 37

eccentrically loaded columns

Question 38

load is applied at any point of the column causing moment at both x and y axes

Answer 38

bi-axially loaded columns

Question 39

All columns are subjected to some bending moment, which may be caused by

Answer 39

(1) end restraint arising from the monolithic placement of floor beams and columns; (2) accidental eccentricity from imperfect alignment and variable materials; (3) asymmetrical floor loads; (4) eccentric loads such as crane loads in industrial buildings, and (5) lateral loading such as from wind or induced by an earthquake.

Question 40

is usually monolithic; thus reinforced concrete frames and arches are common and advantageous.

Answer 40

Concrete construction

Question 41

Based on the position of the _______on the cross section, columns can be classified as concentrically or eccentrically loaded,

Answer 41

load

Question 42

all columns have to be designed for some _______________________due to such causes as imperfections in the vertical alignment of formwork.

Answer 42

unforeseen or accidental eccentricity

Question 43

The _____________ used in the design of columns are the same as for any other type of member.

Answer 43

load factors

Question 44

The _______ factor accounts for the difference between the compressive strength of concrete in a column and that of a concrete cylinder.

Answer 44

0.85

Question 45

provide lateral support so that any tendency to buckling of individual bars would occur only between the tie supports.

Answer 45

LATERAL TIES

Question 46

The ____________ of the longitudinal steel, which begins to yield or to buckle outward, causes additional load on the concrete core.

Answer 46

loss of stiffness

Question 47

Once the core has achieved its crushing strength, the column, unless heavily confined, fails __________.

Answer 47

suddenly

Question 48

All ___________________ bars for tied columns shall be enclosed by lateral ties, at least 10 mm in size for longitudinal bars 32 mm or smaller, and at least 12 mm in size for 36 mm or larger and bundled longitudinal bars.

Answer 48

nonprestressed

Question 49

The center-to-center spacing of the ties shall not exceed ____ longitudinal bar diameters, ___tie bar diameters, or the least dimension of the column.

Answer 49

16 48

Question 50

The clear spacing between ties must be at least __of the maximum aggregate size.

Answer 50

43

Question 51

________________shall be so arranged that every corner and alternate longitudinal bar shall have lateral support provided by the corner of a tie having an included angle of not more than ____ and no bar shall be farther than ___. clear on either side from such a laterally supported bar.

Answer 51

Rectilinear ties 135° 6 in

Question 52

provides the column with the ability to absorb considerable deformation prior to failure.

Answer 52

spiral

Question 53

spiral does actually contribute strength to the column through confinement but is indicated that the spiral was ____times as effective as longitudinal reinforcement in providing column capacity),

Answer 53

2.4

Question 54

anchorage of spiral reinforcement shall be provided by ____ extra turns of spiral bar or wire at each end of the spiral unit

Answer 54

1.5

Question 55

The percentage of total longitudinal reinforcement area Ast in terms of the gross cross-sectional area Ag must be between___ and ___%

Answer 55

1 and 8%

Question 56

_______________ may result from end conditions, inaccuracy of manufacture, or variation in materials even when the load is theoretically concentric.

Answer 56

Accidental eccentricity

Question 57

represents the dividing point between the “compression-controlled” and the “transition zone” regions of the strength interaction diagram.

Answer 57

balanced strain condition, or compression control limit,

Question 58

is measured from the plastic centroid,

Answer 58

eccentricity eb