PC MIDTERMS Flashcards
in prestressed members, the hardware used to transfer force from prestressed reinforcement to the concrete.
ANCHORAGE DEVICE
An anchorage device used with any single strand or a single 16mm or smaller diameter bar
BASIC MONOSTRAND ANCHORAGE DEVICE
An anchorage device used with multiple strands, bars, or wires, or with single bars larger than 16mm diameters
BASIC MULTISTRAND ANCHORAGE DEVICE
An anchorage device that satisfies tests required in Section 425.9.3.1c.
SPECIAL ANCHORAGE DEVICE
in post-tensioned members, the portion of the member through which the concentrated prestressing force is transferred to the concrete and distributed more uniformly across the section; its extent is equal to the largest dimension of the cross section; for anchorage devices located away from the end of a member, the anchorage zone includes the disturbed regions ahead of and behind the anchorage device.
ANCHORAGE ZONE
is a concrete element cast elsewhere than its final position in the structure.
PRECAST CONCRETE
is a conduit, plain or corrugated, to accommodate prestressing reinforcement for post-tensioning applications.
DUCT
is an ability of a structure or member to resist deterioration that impairs performance or limits service life of the structure in the relevant environment considered in design.
DURABILITY
is a distance measured from extreme compression fiber to centroid of tension reinforcement.
EFFECTIVE DEPTH OF SECTION
is a stress remaining in prestressing reinforcement after al losses in Section 420.3.2.6 have occured.
EFFECTIVE PRESTRESS
In prestressed concrete, temporary force exerted by device that introduces tension into prestressing reinforcement.
JACKING FORCE
is a length of frame element over which flexural yielding is intended to occur due to earthquake design displacements, extending not less than a distance h from the critical section where flexural yielding initiates.
PLASTIC HINGE REGION
is a method of prestresing reinforcement in which prestressing reinforcement is tensioned after concrete has harddened.
POST-TENSIONING
is a portion of a prestressed member where flexural tension, calculated using gross section properties, would occur under service loads if the prestress force was not present.
PRECOMPRESSED TENSILE ZONE
is a method of prestressing in which prestressing reinforcement is tensioned before concrete is cast.
PRETENSIONING
is a prestressing reinforcement that has been tensioned to impart forces to concrete.
PRESTRESSED REINFORCEMENT
is a pretensionsed reinforcement or prestressed reinforcement in a bonded tendon.
BONDED PRESTRESSED REINFORCEMENT
is a high-strength reinforcement such as strand, wire, or bar conforming to Section 420.3.1
PRESTRESSING REINFORCEMENT
is a material encasing prestressing reinforcement to prevent bonding of the prestressing reinforcement with the surrounding concrete, to provide corrosion protection, and to contain the corrosion inhibiting coating.
SHEATHING
In post-tensioned members, a tendon is a complete assembly consisting of anchorages, prestressing reinforcement, and sheathing with coating for unbounded applications or ducts filled with grout for bonded applications.
TENDON
A tendon in which prestressed reinforcement is continuously bonded to the concrete through grouting of ducts embedded within the concrete cross section.
BONDED TENDON
is a tendon external to the member concrete cross section in post-tensioned applications.
EXTERNAL TENDON
is a tendon in which prestressed reinforcement is prevented from bonding to the concrete. The prestressing force is permanently transferred to the concrete at the tendon ends by the anchorages only.
UNBONDED TENDON
is a cross section in which the net tensile strength in the extreme tension steel at normal strength is greater than or equal to 0.005.
TENSION-CONTROLLED SECTION
is an act of transferring stress in prestressing reinforcement from jacks or pretensioning bed to concrete member.
TRANSFER
is a length of embedded prestressed reinforcement required to transfer the effective prestress to the concrete.
TRANSFER LENGTH
Design of prestressed members and systems shall be based on strength and on behavior at service conditions at all critical stages during the life of the structure from the time prestress is first applied.
Provisions shall be made for effects on adjoining construction of elastic and plastic deformations, deflections, changes in length, and rotations due to prestressing. _____ shall also be considered.
Effects of temperature change
Restraint of attached structural members
Foundation settlement
Creep
Shrinkage
_____ due to prestressing shall be considered in design.
Stress concentrations
_____ shall be considered in computing section properties before grout in post-tensioning ducts has attained design strength.
Effect of loss of area due to open ducts
_____ shall be permitted to be external to any concrete section of a member. Strength and serviceability design requirements of this Code shall be used to evaluate the effects of external tendon forces on the concrete structure.
Post-tensioning tendons
Required strength U shall include internal load effects due to reactions induced by prestressing with a load factor of ___.
1.0
For post-tensioned anchorage zone design, a load factor of ___ shall be applied to the maximum prestressing reinforcement jacking force.
1.2
The load factor on live load l in Eqs. 405.3.1c, 405.3.1d, and 405.3.1e shall be permitted to be reduced to ___ except for (a), (b), or (c): a. Garages;
b. Areas occupied as places of public assembly;
c. Areas where L is greater than 4.8 kPa.
0.5
Radius of gyration is equal to ___ times the dimension in the direction stability is being considered for rectangular columns
0.30
Radius of gyration is equal to ___ times the diameter of circular columns.
0.25
Prestressed slabs shall be classified as __________ in accordance with Section 424.5.2.
Class U, Class T. or Class C
Stresses in prestressed slabs immediately after transfer and at service loads shall not exceed the _____ in Sections 424.5.3 and 424.5.4.
permissible stresses
For _____, effects of reactions induced by prestressing shall be considered in accordance with Section 405.3.11.
prestressed slabs
For prestressed slabs, _____ shall be considered as unbonded tendons in calculating flexural strength, unless the external tendons are effectively bonded to the concrete section along its entire length.
external tendons
For slabs with bonded prestressed reinforcement, total quantity of As and Aps shall be adequate to develop a factored load at least ___ times the cracking load calculated on the basis of fr as given in Section 419.2.3.
1.2
For slabs with both flexural and shear design strength at least _____, Section 407.6.2.1 need not be satisfied.
twice the required strength
For slabs with unbonded tendons, the minimum area of bonded deformed longitudinal reinforcement, Asmin, shall be:
Asmin >= 0.004Act
is the area of that part of the cross section between the flexural tension face and the centroid of the gross section.
A(ct)
Is a concrete in which internal stresses have been introduced to reduce potential tensile stresses in concrete resulting from service loads.
PRESTRESSED CONCRETE
STRENGTH REDUCTION FACTOR:
Moment, axial force, or combined moment and axial force.
Exception: near end of pretensioned members where strands are not fully developed.
0.65 - 0.90
STRENGTH REDUCTION FACTOR:
Shear
Exception: additional requirements are given in section 421.2.4 for structures designed to resist earthquake effects.
0.75
STRENGTH REDUCTION FACTOR:
Torsion
0.75
