I-kiir

On kaks standardset I-tala vormi:

• Rolled I-beam, formed by kuumvaltsimine, külmvaltsimine or ekstrusioon (depending on material).

• Plaattala, formed by keevitamine (or occasionally poltidega kinnitamine or neetimine) plaadid.

I-beams are commonly made of konstruktsiooniteras but may also be formed from alumiiniumist or other materials. A common type of I-beam is the valtsitud terastala (RSJ)—sometimes incorrectly rendered as tugevdatud terasest tala. Briti and Euroopa standardid also specify Universal Beams (UBs) and Universal Columns (UCs). These sections have parallel flanges, as opposed to the varying thickness of RSJ flanges which are seldom now rolled in the UK. Parallel flanges are easier to connect to and do away with the need for tapering washers. UCs have equal or near-equal width and depth and are more suited to being oriented vertically to carry axial load such as columns in multi-storey construction, while UBs are significantly deeper than they are wide are more suited to carrying bending load such as beam elements in floors.

I-talad—I-beams engineered from wood with puitkiudplaat and/or lamineeritud spoon saematerjal—are also becoming increasingly popular in construction, especially residential, as they are both lighter and less prone to warping than solid wooden talad. Siiski on muret tekitanud nende kiire tugevuse kadumine tulekahjus, kui neid ei kaitsta.

Disain painutamiseks 

Suurimad pinged (${\displaystyle \sigma _{xx}}$) painutatud talas asuvad neutraalteljest kõige kaugemal asuvates kohtades.

A beam under bending sees high stresses along the axial fibers that are farthest from the neutraaltelg. Rikke vältimiseks peab suurem osa tala materjalist asuma nendes piirkondades. Neutraalse telje lähedases piirkonnas on materjali vaja suhteliselt vähe. See vaatlus on I-tala ristlõike- aluseks; neutraaltelg kulgeb mööda võre keskpunkti, mis võib olla suhteliselt õhuke ja suurem osa materjalist võib olla koondunud äärikutesse.

The ideal beam is the one with the least cross-sectional area (and hence requiring the least material) needed to achieve a given sektsiooni moodul. Since the section modulus depends on the value of the inertsimoment, peab tõhusa tala suurem osa materjalist asuma neutraalteljest võimalikult kaugel. Mida kaugemal on antud kogus materjali neutraalteljest, seda suurem on ristlõike moodul ja seega saab vastu pidada suuremale paindemomendile.

When designing a symmetric I-beam to resist stresses due to bending the usual starting point is the required section modulus. If the allowable stress is ${\displaystyle \sigma _{\mathrm {max} }}$ and the maximum expected bending moment is ${\displaystyle M_{\mathrm {max} }}$, siis nõutav lõigumoodul on antud³

• ${\displaystyle S={\cfrac {M_{\mathrm {max} }}{\sigma _{\mathrm {max} }}}={ \cfrac {I}{c}}}$

where ${\displaystyle I}$ is the moment of inertia of the beam cross-section and ${\displaystyle c}$ is the distance of the top of the beam from the neutral axis (see talade teooria for more details).

For a beam of cross-sectional area ${\displaystyle a}$ and height ${\displaystyle h}$, the ideal cross-section would have half the area at a distance ${\displaystyle h/2}$ above the cross-section and the other half at a distance ${\displaystyle h/2}$ below the cross-section.³ For this cross-section

• ${\displaystyle I={\cfrac {ah{2}}{4}};S=0.5ah}$

Neid ideaalseid tingimusi ei saa aga kunagi saavutada, sest materjali on veebis vaja füüsilistel põhjustel, sealhulgas paindumise vältimiseks. Laiade{0}}ääriktalade puhul on ristlõike moodul ligikaudu

• ${\displaystyle S\umbes 0.35ah}$

mis on parem kui ristkülikukujuliste talade ja ringikujuliste talade abil saavutatav.

Probleemid 

Though I-beams are excellent for unidirectional bending in a plane parallel to the web, they do not perform as well in bidirectional bending. These beams also show little resistance to twisting and undergo sectional warping under torsional loading. For torsion dominated problems, kasti talad and other types of stiff sections are used in preference to the I-beam.

Kujundid ja materjalid (USA) 

Roostes neetitud terasest I-tala

Ameerika Ühendriikides on kõige sagedamini mainitud I-talaks laia-ääriku (W) kuju. Nendel taladel on äärikud, mille sisepinnad on suurema osa nende pindalast paralleelsed. Muud I-talad hõlmavad Ameerika standardseid (tähisega S) kujundeid, mille puhul siseääriku pinnad ei ole paralleelsed, ja H-vaia (tähisega HP), mida tavaliselt kasutatakse vaivundamentidena. Laiad-ääriku kujundid on saadaval klassis ASTM A992,⁴ which has generally replaced the older ASTM grades A572 and A36. Ranges of yield strength:

• A36: 36,000 psi (250 MPa)

• A572: 42,000–60,000 psi (290–410 MPa), with 50,000 psi (340 MPa) the most common

• A588: Similar to A572

• A992: 50,000–65,000 psi (340–450 MPa)

Nagu enamik terastooteid, sisaldavad ka -talad sageli taaskasutatud sisu.

Standardid 

Järgmised standardid määravad I-tala terassektsioonide kuju ja tolerantsid:

Euroopa standardid 

• EN 10024, Hot rolled taper flange I sections – Tolerances on shape and dimensions.

• EN 10034, Structural steel I and H sections – Tolerances on shape and dimensions.

• EN 10162, Cold rolled steel sections – Technical delivery conditions – Dimensional and cross-sectional tolerances

AISC käsiraamatmuuda

The Ameerika teraseehituse instituut (AISC) publishes the Steel Construction Manual for designing structures of various shapes. It documents the common approaches, Lubatud tugevuse disain (ASD) and Koormus- ja takistusteguri disain (LRFD), (starting with 13th ed.) to create such designs.

muud 

• DIN 1025-5

• ASTM A6, Ameerika standardtalad

• BS 4-1

• IS 808 – Dimensions hot rolled steel beam, column, channel and angle sections

• AS/NZS 3679,1 – Australia and New Zealand standard⁵

Nimetus ja terminoloogia 

Lai-ääriku I-tala.

• In the Ühendriigid, steel I-beams are commonly specified using the depth and weight of the beam. For example, a "W10x22" beam is approximately 10 in (254 mm) in depth (nominal height of the I-beam from the outer face of one flange to the outer face of the other flange) and weighs 22 lb/ft (33 kg/m). Wide flange section beams often vary from their nominal depth. In the case of the W14 series, they may be as deep as 22.84 in (580 mm).⁶

• In Kanada, steel I-beams are now commonly specified using the depth and weight of the beam in metric terms. For example, a "W250x33" beam is approximately 250 millimetres (9.8 in) in depth (height of the I-beam from the outer face of one flange to the outer face of the other flange) and weighs approximately 33 kg/m (22 lb/ft; 67 lb/yd).⁷ I-beams are still available in U.S. sizes from many Canadian manufacturers.

• In Mehhiko, steel I-beams are called IR and commonly specified using the depth and weight of the beam in metric terms. For example, a "IR250x33" beam is approximately 250 mm (9.8 in) in depth (height of the I-beam from the outer face of one flange to the outer face of the other flange) and weighs approximately 33 kg/m (22 lb/ft).⁸

• In India I-beams are designated as ISMB, ISJB, ISLB, ISWB. ISMB: Indian Standard Medium Weight Beam, ISJB: Indian Standard Junior Beams, ISLB: Indian Standard Light Weight Beams, and ISWB: Indian Standard Wide Flange Beams. Beams are designated as per respective abbreviated reference followed by the depth of section, such as for example ISMB 450, where 450 is the depth of section in millimetres (mm). The dimensions of these beams are classified as per IS:808 (as per BIS).^{tsitaat vaja}

• In the Ühendkuningriik, these steel sections are commonly specified with a code consisting of the major dimension (usually the depth){{0}}x-the minor dimension-x-the mass per metre-ending with the section type, all measurements being metric. Therefore, a 152x152x23UC would be a column section (UC = universal column) of approximately 152 mm (6.0 in) depth 152 mm width and weighing 23 kg/m (46 lb/yd) of length.⁹

• In Austraalia, these steel sections are commonly referred to as Universal Beams (UB) or Columns (UC). The designation for each is given as the approximate height of the beam, the type (beam or column) and then the unit metre rate (e.g., a 460UB67.1 is an approximately 460 mm (18.1 in) deep universal beam that weighs 67.1 kg/m (135 lb/yd)).⁵

Mobiilside talad 

Mobiilside talad are the modern version of the traditional "kastelleeritud tala" which results in a beam approximately 40–60 percent deeper than its parent section. The exact finished depth, cell diameter and cell spacing are flexible. A cellular beam is up to 1.5 times stronger than its parent section and is therefore utilized to create efficient large span constructions.¹⁰