Reinforced concrete-1

After cracking the stiffness of a reinforced concrete beam is

decreased

Well graded aggregates will require minimum… to fill up the voids in the concrete mixture volume

cement paste

the property of concrete to continue to deform with time under substained loads at unit stresses within the accepted elastic ranges is called

creep

In a reinforced concrete beam, a section may be considered virtually…. until the steel yield and then the plastic until the concrete fails at compression

elastic

Analysis of section subjected to…. can be dine replacing the real element with a virtual spatial truss.

torsion

The shear reinforcement should form an angle of between ... to the longitudinal axis of the structural element

45 degrees and 90 degrees

The minimum spacing of reinforcements, to permit concrete flow around depends by the reinforcement diameter and by...

the maximum aggregate size.

The limit states corresponding to the conditions beyond which specified service requirements( deformations, deflections, vibrations, crackings of the concrete that effect durability) for a structure of structural member are no longer met or called...

serviceability limit states

The phenomenon that appears at the concrete strengthening and consists in the reducing of its volume, independent by the loads application is called

shrinkage.

Explain why after cracking the stiffness of a reinforced concrete beam decreases

Stiffness decreases significantly because a portion of the cross-section (the tension-side concrete) is no longer effective.

Give some examples where compression reinforcements are needed and used in the structural design reinforced concrete beam section?

In cases of deep beams, curved beams, or beams subjected to large loads.

The limit state assiciated with collapse, loss of equilibrium of the whole structure, failure by excessive deformation, rupture or loss of stability, are called

ultimate limit state

For a crack widths up to a maximum of 0.30 mm the SLS of cracking may be verified without calculation by limiting the diameter of reinforcing bars as a function of

corrosion effect

Lower strength concrete has … ductility than higher-strength concrete

lower

Concrete and steel exhibit … after being subjected to high temperature

reduced strength

the design of members with shear reinforcement is based on

truss model

the crack due to torsion will form ... the member

a spiral around

the length necessary for developing the required tensile force in an anchorage or lap is calculated on the basics of a

constant bond stress

As a result of … a reduction of the steel crosss section, cracking or spalling of the concrete will occure

corrosion

Tensile forces are transmitted from one bar ti another by lapping of bars welding or

hooks

if the reinforcing bars … is not adequate, the bars will slip within the concrete

bond

the conrete will crack in the region of tensile and then, all the tension is cariied by

reinforcement

…. are time-dependent deformations

creep and shrinkage

The spacing of bars shall be such that the concrete can be placed and compacted to

assure and adequate bond

in order to reduce the cross-section size of a beam, to control the long-term deflection or when alternative bending moments act … must be used

compression reinforcement

The minimum reinforcement ratio is the lowest relative amount of steel permitted to prevent the …

brittle failure