ISO 21725-2:2021 プレストレストコンクリート橋の簡略化された設計—パート2：箱桁橋 | ページ 6

3.1

admixture

material other than water, aggregate, or hydraulic cement, used as an ingredient of concrete and added to concrete before or during its mixing to modify its properties

3.2

anchorage

device used to anchor a non-structural element to the structural framing

3.3

B-region

portion of a member in which it is reasonable to assume that strains due to flexure vary linearly through section

3.4

beam

horizontal, or nearly horizontal, structural member supported at one (such as a cantilever) or more points, but not throughout its length, transversely supporting a load, and subjected primarily to flexure

3.5

clearance

distance by which one thing clears another; the space between them

3.6

compression reinforcement

reinforcement provided to resist compression stresses induced by flexural moments acting on the member section

3.7

specified compressive strength of concrete

compressive cylinder strength of concrete used in design and evaluated in accordance with the appropriate ISO standard, expressed in megapascals (MPa)

Note 1 to entry: Whenever the quantity f_c’ in under a radical sign (), the positive square root of numerical value only is intended, and the result has units of megapascals (MPa).

3.8

corrosion

gradual removal or weakening of metal from its surface that requires the presence of humidity and oxygen, and is helped by the presence of other materials

3.9

cover

thickness of concrete between surface of any reinforcing bar and the nearest face of the concrete member

3.10

crosstie

continuous reinforcing bar having a 135° hook at one end and a hook not less than 90° at least a six-diameter extension at the other end

Note 1 to entry: The hooks should engage peripheral longitudinal bars. The 90° hooks of two successive crossties engaging the same longitudinal bars should be alternated end for end.

3.11

D-region

portion of a member with a force discontinuity or a geometric discontinuity

3.12

deformed reinforcement

steel reinforcement that has deformations in its surface to increase its bond to the concrete

Note 1 to entry: The following steel reinforcement should be considered deformed reinforcement according to this document: deformed reinforcing bars, deformed wire, welded plain wire fabric, and welded deformed wire fabric conforming to the appropriate ISO standards.

3.13

design strength

product of the nominal strength multiplied by a strength reduction factor

3.14

development length

length of embedded reinforcement required to develop the design strength of reinforcement at a critical section

3.15

diaphragm

transverse stiffener which is provided between girders in order to maintain section geometry, to resist lateral forces, and to transfer loads to support

3.16

duct

material creating a conduit in a concrete member to accommodate the prestressing steel of a post-tensioning tendon

3.17

durability

characteristic of a structure to resist gradual degradation of its serviceability in a given environment for the design service life

3.18

effective depth

distance measured from extreme compression fibre to centroid of tension reinforcement

3.19

factored load

specified nominal load multiplied by the load factors prescribed in this document

3.20

girder

main horizontal support beam, usually supporting other beams

3.21

hook

bend at the end of a reinforcing bar

Note 1 to entry: They are defined by the angle that the bend forms with the bar as either 90°, 180° or 135° hooks.

3.22

jacking force

<prestressed concrete> temporary force exerted by the device that introduces tension into the tendons

3.23

joist

T-shaped beam used in parallel series directly supporting deck loads, and supported in turn by larger girders, beams, or bearing structural concrete walls

3.24

lap splice

splice between two reinforcing bars obtained by overlapping them for a specified length

3.25

limit state

condition beyond which a structure or member becomes unfit for service and is judged either to be no longer useful for its intended function (serviceability limit state) or to be unsafe (strength limit state)

3.26

live load

static and dynamic effect, in terms of forces applied on the structure, produced by the use of the bridge by pedestrians and/or vehicles and not including construction or environmental loads

3.27

load effect

force and deformation produced in structural members by the applied loads

3.28

load combination

combination of factored loads and forces as specified in this document

3.29

load factor

factor that accounts for deviations of the actual load from the nominal load, for uncertainties in the analysis that transforms the load into a load effect, and for the probability that more than one extreme load will occur simultaneously

3.30

load

force or other action that results from the weight of all bridge materials, pedestrians, vehicles, environmental effects, differential movement, and restrained dimensional changes

3.31

longitudinal reinforcement

reinforcement that is laid parallel to the longitudinal axis of the element, generally to account for flexural effects

3.32

mesh wire

welded-wire fabric reinforcement

3.33

nominal load

magnitude of the loads specified in this document (dead, live, soil, wind, snow, rain, flood, and earthquake)

3.34

nominal strength

capacity of a structure or member to resist the effects of loads, as determined by computations using specified material strengths and dimensions and the Formulae set forth in this document

Note 1 to entry: Specified material strengths are derived from accepted principles of structural mechanics or by field tests or laboratory tests of scaled models, allowing for modelling effects and differences between laboratory and field conditions.

3.35

permanent load

load in which variations over time are rare or of small magnitude

Note 1 to entry: All other loads are variable loads (see also 3.33).

3.36

post-tensioning

method of prestressing reinforced concrete in which tendons are tensioned after the concrete has attained a specified minimum strength or a specified minimum age

3.37

prestressing steel

high-strength steel elements such as wire, bar, or strands used to impart prestress forces to concrete

3.38

pretensioning

method of prestressing in which prestressing steel is tensioned before the concrete is placed

3.39

required factored strength

strength of a member or cross-section required to resist factored loads or related internal moments and forces in such combinations as are stipulated by this document

3.40

service load

load specified by this document (without load factors)

3.41

shrinkage and temperature reinforcement

reinforcement normal to flexural reinforcement provided for shrinkage and temperature stresses in structural solid slabs and footings where flexural reinforcement extends in one direction only

3.42

skew

difference or deviation from an expected or optimal value; in the case of bridges, deviation of the longitudinal axis of the deck with respect to a line perpendicular to the length of the abutments

3.43

slab

deck

upper flat part of a reinforced concrete deck carried by supporting joists or beams or girders

3.44

spiral reinforcement

continuously wound reinforcement in the form of a cylindrical helix

3.45

stirrup

reinforcement used to resist shear and torsion stresses in a structural member

Note 1 to entry: Typically bars, wires, or welded-wire fabric (plain or deformed) either single leg or bent into L, U, or rectangular shapes and located perpendicular to or at an angle to longitudinal reinforcement. (The term"stirrups" is usually applied to lateral reinforcement in girders, beams, and joists; the term"ties" to those in columns and walls, perhaps because they are intended also as confinement for the longitudinal reinforcement). See also 3.48.

3.46

strength reduction factor

coefficient that accounts for deviations of the actual strength from the nominal strength, according to the manner and consequences of failure

Note 1 to entry: Including the probability of understrength members due to variations in material strengths and dimensions, approximations in the design Formulae, to reflect the degree of ductility and required reliability on the member under the load effects being considered, and to reflect the importance of the element in the structure.

3.47

tendon

an assembly consisting of a tensioned element (such as a wire, bar, rod, strand, or a bundle of these elements) used to impart compressive stress in concrete, along with any associated components used to enclose and anchor the tensioned element

3.48

tie

loop of reinforcing bar or wire enclosing longitudinal reinforcement

Note 1 to entry: A continuously wound bar or wire in the form of a circle, rectangle, or other polygon shape without re-entrant corners is acceptable.

3.49

transfer length

the length from the end of the member where the tendon stress is zero to the point along the tendon where the prestress is fully effective

3.50

transverse reinforcement

reinforcement located perpendicular to the longitudinal axis of the element, comprising stirrups, ties, spiral reinforcement, among others

3.51

yield strength

specified minimum yield strength or yield point of reinforcement

Note 1 to entry: The yield strength is expressed in units of megapascals (MPa).

Note 2 to entry: Applicable International Standards specify that the yield strength or yield point be determined in tension.