AT03 - Beam

Question 1

A rigid structural member designed to carry and transfer transverse loads across space to supporting elements.

Answer 1

BEAM

Question 2

The extent of space between two supports of a structure. Also the structure so supported.

Answer 2

SPAN

Question 3

The distance between the inner faces of the supports of a span.

Answer 3

CLEAR SPAN

Question 4

The center-to-center distance between the supports of a span.

Answer 4

EFFECTIVE SPAN

Question 5

An external moment tending to cause part of a structure to rotate or bend, equal to the algebraic sum of the moments about the neutral axis of the section under consideration.

Answer 5

BENDING MOMENT

Question 6

An internal moment equal and opposite to a bending moment, generated by a force couple to maintain equilibrium of the section being considered.

Answer 6

RESISTING MOMENT

Question 7

The perpendicular distance a spanning member deviates from a true course under transverse lading, increasing with load and span, and decreasing with an increase in the moment of inertia of the section or the modulus of elasticity of the material.

Answer 7

DEFLECTION

Question 8

A slight convex curvature intentionally built into a beam, girder, or truss to compensate for an anticipated deflection.

Answer 8

CAMBER

Question 9

A shear force at a cross section of a beam or other member subject to bending, equal to the algebraic sum of transverse forces on one side of the section.

Answer 9

TRANSVERSE SHEAR

Question 10

The shearing stress developed to prevent slippage along horizontal planes of a beam under transverse loading, equal at any point to the vertical shearing stress at that point. Also called longitudinal shearing stress.

Answer 10

HORIZONTAL SHEARING STRESS

Question 11

The shearing stress developed to prevent slippage along horizontal planes of a beam under transverse loading, equal at any point to the vertical shearing stress at that point. Also called horizontal shearing stress.

Answer 11

LONGITUDINAL SHEARING STRESS

Question 12

The shearing stress developed along a cross section of a beam to resist transverse shear, having a maximum value at the neutral axis and decreasing nonlinearly toward the outer faces.

Answer 12

VERTICAL SHEARING STRESS

Question 13

A combination of compressive and tensile stresses developed at a cross section of a structural member to resist a transverse force, having a maximum value at the surface furthest from the neutral axis.

Answer 13

BENDING STRESS

Question 14

An imaginary line passing through the centroid of the cross section of a beam or other member subject to bending, along which no bending stresses occur.

Answer 14

NEUTRAL AXIS

Question 15

A formula defining the relationship between bending moment, bending stress, and the cross-sectional properties of a beam. Bending stress is directly proportional to bending moment and inversely proportional to the moment of inertia of a beam section.

Answer 15

FLEXURE FORMULA

Question 16

Flexure Formula in terms of fb, M, c, and I.

Answer 16

fb = Mc/I

Question 17

The extreme fiber stress in bending on the Flexure Formula.

Answer 17

fb

Question 18

The bending moment on the Flexure Formula.

Answer 18

M

Question 19

The distance from neutral axis to the outermost surface in bending on the Flexure Formula.

Answer 19

c

Question 20

The moment of inertia on the Flexure Formula.

Answer 20

I

Question 21

The sum of the products of each element of an area and the square of its distance from a coplanar axis of rotation. It is a geometric property that indicates how the cross-sectional area of a structural member is distributed and does not reflect the intrinsic physical properties of a material.

Answer 21

MOMENT OF INERTIA

Question 22

Section Modulus Formula in terms of S, I, and c

Answer 22

S = I/c

Question 23

A geometric property of a cross section defined as the moment of inertia of the section divided by the distance from the neutral axis to the most remote surface.

Answer 23

SECTION MODULUS

Question 24

Flexure Formula in terms of fb, M, and S.

Answer 24

fb = M/S

Question 25

**Complete** Flexure Formula

Answer 25

**fb** = **Mc**/**I** where * *fb** = *extreme* **fiber *stress*** in bending * *M** = bending **moment** * *c** = *distance* from **neutral axis** to the ***outermost surface*** in bending * *I** = moment of **inertia** if **I**/**c** = **S** where **S** = **section** modulus then **fb** = **M**/**S**

Question 26

**Halving** the *beam span* ***reduces*** the *bending stresses* by what factor?

Answer 26

**FACTOR** OF **2**

Question 27

**Doubling** the *beam width* ***reduces*** the *bending stresses* by what factor?

Answer 27

**FACTOR** OF **2**

Question 28

**Doubling** the *beam depth* ***reduces*** the *bending stresses* by what factor?

Answer 28

**FACTOR** OF **4**

Question 29

How does the **efficiency** of a beam ***increased*** with regards to *moment of inertia* (**I**) and *section modulus* (**S**)?

Answer 29

**PROVIDE** required **I** or **S** with the **SMALLEST POSSIBLE AREA**

Question 30

How does the required *moment of inertia* (**I**) or *section modulus* (**S**) provided while at the same time **minimizing** the *cross-sectional **area*** of the *beam*.

Answer 30

**MAKE SECTION DEEP** with **MOST of MATERIALS** at **EXTREMETIES** where the ***maximum bending stresses occur***.

Question 31

The *buckling* of a structural member ***induced*** by **compressive stresses** acting on a **slender portion** *insufficiently rigid* in the **lateral** direction.

Answer 31

**LATERAL** BUCKLING

Question 32

The **tensile** and **compressive *stresses*** resulting from the *interaction* of ***bending*** and ***shear* stresses** at a *cross-section* of a beam.

Answer 32

**PRINCIPAL** STRESSES

Question 33

The *part* of the beam in which *only* **bending stresses** **exist** and the ***principal stresses*** are *equivalent* to the ***tensile*** and ***compressive stresses*** resulting from **bending**.

Answer 33

**EXTREME SURFACES** OF **BEAM**

Question 34

The *part* of the beam in which *only* **shear stresses** exist and these can be resolved into ***tensile*** and ***compressive stresses*** acting at **45°** *angles* to it.

Answer 34

**NEUTRAL AXIS** OF **BEAM SECTION**

Question 35

The *part* of the beam subject to both **bending** and **shear stresses**, the ***principal stresses*** have an *inclination* determined by the ***relative magnitudes*** of these stresses.

Answer 35

**INTERMEDIATE ELEMENTS** OF **BEAM**

Question 36

The *point* in the cross-sectional plane of a structural member through which a ***transverse load*** **must pass** in order to ***prevent*** **torsion** or **twisting** of the member *about* a *longitudinal axis*.

Answer 36

**SHEAR** CENTER

Question 37

*Lines* depicting the **direction** ***but not*** the *magnitude* of the ***principal stresses*** in a beam.

Answer 37

STRESS **TRAJECTORIES**

Question 38

*Stress* caused by **bending** *surfaces* **inward**.

Answer 38

**COMPRESS**ION

Question 39

*Stress* caused by **bending** *surfaces* **outward**.

Answer 39

**TENS**ION

Question 40

A *graphic representation* of the *variation* in ***magnitude*** of the **external shears** present in a structure for a given set of ***transverse loads*** and ***support conditions***.

Answer 40

**SHEAR** DIAGRAM

Question 41

*Loads* that produce **external *shears*** that are **constant** in *magnitude* between *loads*.

Answer 41

**CONCENTRATED** LOADS

Question 42

*Loads* that produce **linearly varying *shears***.

Answer 42

**UNIFORMLY DISTRIBUTED** LOADS

Question 43

A *graphic representation* of the *variation* in ***magnitude*** of the **bending moments** present in a structure for a given set of **transverse loads** and **support conditions**. The **overall deflected shape** of a structure subject to bending can often be *inferred* from the **shape of** its **moment diagram**.

Answer 43

**MOMENT** DIAGRAM

Question 44

*Loads* that produce **bending *moments*** that **vary linearly** between loads.

Answer 44

**CONCENTRATED** LOADS

Question 45

*Loads* that produce **parabolically varying *moments***.

Answer 45

**UNIFORMLY DISTRIBUTED** LOADS

Question 46

A *beam* resting on **simple supports** at ***both ends***, which are *free to rotate* and have **no moment resistance**. As with any statically determinate structure, the **values** of all ***reactions***, ***shears***, and ***moments*** for a simple beam are **independent** of its *cross-sectional shape* and *material*.

Answer 46

**SIMPLE** BEAM

Question 47

A **projecting beam** *supported* at only ***one fixed end***.

Answer 47

**CANTILEVER** BEAM

Question 48

A *beam* or other *rigid structural member* **extending** *beyond* a ***fulcrum*** and **supported** by a ***balancing member*** or a ***downward force*** *behind* the ***fulcrum***.

Answer 48

CANTI**LEVER**

Question 49

A *simple beam* **extending** *beyond **one*** of its *supports*. The *overhang* **reduces** the **positive moment** at ***midspan*** while **developing** a **negative moment** at the ***base*** of the ***cantilever*** over the support.

Answer 49

**OVERHANGING** BEAM

Question 50

A *simple beam* **extending** *beyond **both*** of its *supports*.

Answer 50

**DOUBLE OVERHANGING** BEAM

Question 51

A *net* ***resultant*** of ***shear forces*** that *acts* **vertically upward** on the left part of the structure being considered.

Answer 51

**POSITIVE** SHEAR

Question 52

A *net* ***resultant*** of ***shear forces*** that *acts* **vertically downward** on the left part of the structure being considered.

Answer 52

NEGATIVE SHEAR

Question 53

A ***bending moment*** that *produces* a **concave curvature** at a *section* of a structure.

Answer 53

**POSITIVE** MOMENT

Question 54

A ***point*** at which a structure **changes curvature** from *convex* to *concave* or *vice versa* as it ***deflects*** under a ***transverse load***; theoretically, an **internal hinge** and therefore a **point of zero moment**.

Answer 54

**INFLECTION** POINT

Question 55

A ***bending moment*** that *produces* a **convex curvature** at a *section* of a structure.

Answer 55

**NEGATIVE** MOMENT

Question 56

The *part of a beam* that is **thickened** or **deepened** to ***develop*** **greater moment resistance**. The **efficiency** of a beam can be ***increased*** by ***shaping its length*** in *response* to the **moment** and **shear values**, which typically vary *along* its ***longitudinal axis***.

Answer 56

**HAUNCH**

Question 57

A *beam* having *both ends* **restrained against *translation*** and ***rotation***. The *fixed ends* ***transfer** bending **stresses***, ***increase*** the ***rigidity*** of the *beam*, and ***reduce*** its *maximum **deflection***.

Answer 57

**FIXED-END** BEAM

Question 58

A *simple beam* **supported by** the **cantilevers of two adjoining spans** with ***pinned construction** **joints*** at *points* of *zero moment*. Also called **hung-span**.

Answer 58

**SUSPENDED**-SPAN

Question 59

A *simple beam* **supported by** the **cantilevers of two adjoining spans** with ***pinned construction joints*** at *points* of *zero moment*. Also called **suspended-span**.

Answer 59

**HUNG**-SPAN

Question 60

A *beam* **extending** over **more than two supports** in order to ***develop greater rigidity*** and ***smaller moments*** than a series of simple beams having similar spans and loading. Both ***fixed-end*** and ***continuous beams*** are **indeterminate structures** for which the values of all *reactions*, *shears*, and *moments* are **dependent** not only **on *span*** and ***loading*** but also on ***cross-sectional shape*** and ***material***.

Answer 60

**CONTINUOUS** BEAM

Question 61

The **distance** *between* **inflection points** in the span of a ***fixed-end*** or ***continuous beam***, *equivalent* in nature to the **actual length** of a **simply supported beam**.

Answer 61

**EFFECTIVE** LENGTH