Chapter 2: Specifications, Loads And Methods Of Design

Question 1

adopted by nearly all building codes;
Standard setting body of steels

Answer 1

AISC ( American Institute of Steel Construction)

Question 2

adopted by nearly all state highway and transportation departments

Answer 2

AASHTO (American Association of State Highways and Transportations Officials)

Question 3

they are written, not for the purpose of restricting engineers, but for the purpose of protecting the public

Answer 3

Specifications

Question 4

The intent of Specifications is that the loading used for design be the one that causes the largest stresses

Answer 4

TRUE

Question 5

This was developed because of the need for a modern building code that emphasizes performance

Answer 5

International Building Code (IBC)

Question 6

IBC is intended to provide a model set of regulations to safeguard the public in all communities.

Answer 6

TRUE

Question 7

an up-to-date structural code addressing the design and installation of structural systems through requirements emphasizing performance through various model codes/regulations, generally from the United States, to safeguard the public health and safety nationwide

Answer 7

National Structural Code of the Philippines (NSCP)

Question 8

establishes minimum requirements for structural systems using prescriptive and performance-based provisions

Answer 8

NSCP

Question 9

What is the most difficult and most important task of a structural engineer?

Answer 9

Accurate estimation of Loads

Question 10

what are the three classification of loads according to their character and duration of application.

Answer 10

1. Dead Loads
2. Live Loads
3. Environmental Loads

Question 11

-loads of constant magnitude that remain in one position
-consist of the structural frame’s own weight and other loads that are permanently attached to the frame

Answer 11

Dead Loads

Question 12

Example of dead loads

Answer 12

for a steel-frame building, the frame, walls, floors, roof, plumbing, and fixtures

Question 13

loads that may change in position and magnitude;
caused when a structure is occupied, used, and maintained

Answer 13

Live Loads

Question 14

Classification of Live loads;

Answer 14

Moving and movable loads

Question 15

live loads that move under their own power, such as trucks, people, and cranes

Answer 15

Moving Loads

Question 16

live loads that may be moved, such as furniture and warehouse materials

Answer 16

Movable loads

Question 17

Other types of live loads:

Answer 17

Floor loads
Traffic Loads for bridges
Impact Loads
Longitudinal Loads

Question 18

bridges are subjected to series of concentrated loads of varying
magnitude caused by groups of truck or train wheels

Answer 18

Traffic Loads for bridges

Question 19

are caused by the vibration of moving or movable loads

Answer 19

Impact Loads

Question 20

stopping a train on a railroad bridge or a truck on a highway bridge causes longitudinal forces to be applied

Answer 20

Longitudinal loads

Question 21

exertion of lateral earth pressures on walls or upward pressures on foundations

Answer 21

Soil Pressure

Question 22

water pressure on dams, inertia forces of large bodies of water during earthquakes, and uplift pressures on tanks and basement
structures

Answer 22

Hydrostatic pressures

Question 23

Cause by explosions, sonic booms, military weapons

Answer 23

Blast loads

Question 24

This is due to the changes in temperature, causing structural deformations and resulting structural forces

Answer 24

Thermal forces

Question 25

Those on curved bridges and caused by trucks and trains or similar effects on roller coasters

Answer 25

Centrifugal forces

Question 26

This load is caused by the environment in which a particular structure is located.

Answer 26

Environmental loads

Question 27

This is under rain loads. This is the result if water on a flat roof accumulates faster that it runs off.

Answer 27

Ponding

Question 28

wind forces act as pressures on vertical windward surfaces, pressures or suction on sloping windward surfaces (depending on the slope), and suction on flat surfaces and on leeward vertical and sloping surfaces (due to the creation of negative pressures or vacuums)

Answer 28

Wind Loads

Question 29

there is an acceleration of the ground surface motion; vertical and horizontal components – the vertical component is assumed to be negligible

Answer 29

Earthquake loads

Question 30

It is needed for the expected effects of an earthquake should include a study of the structure’s response to the ground motion caused by the earthquake

Answer 30

Structural analysis

Question 31

the movement or displacement of one story of a building with respect to the floor above or below

Answer 31

Drift

Question 32

two acceptable methods for designing structural steel members and their connections

Answer 32

LRFD (Load and Resistance Factor Design) ASD (Allowable Strength Design)

Question 33

This provides boundaries of structural usefulness

Answer 33

Limit state

Question 34

used to describe a condition at which a structure or part of a structure ceases to perform its intended function

Answer 34

Limit state

Question 35

define load-carrying capacity, including excessive yielding, fracture, buckling, fatigue, and gross rigid body motion

Answer 35

Strength limit states

Question 36

Define performance, including deflection, cracking, slipping, vibration, and deterioration

Answer 36

Serviceability limit states

Question 37

Its calculated theoretical strength, with no safety factors (Ω) or resistance factors (𝜙) applied

Answer 37

The nominal strength of a member

Question 38

resistance factor, usually less than 1.0, is multiplied by the nominal strength of a member

Answer 38

LRFD method

Question 39

nominal strength is divided by a safety factor, usually greater than 1.0

Answer 39

ASD method

Question 40

possible service load groups are formed, and each service load is multiplied by a load factor, normally larger than 1.0, to account for the uncertainty of that particular load

Answer 40

LRFD Load Combinations

Question 41

the resulting linear combination of service loads in a group, each multiplied by its respective load factor

Answer 41

Factored Load

Question 42

used to compute the moments, shears, and other forces in the structure

Answer 42

Largest values determined

Question 43

(reduction factor 𝜙)(nominal strength of a member) ≥ computed factored force in member, 𝑅𝑢 or 𝜙𝑅𝑛 ≥ 𝑅𝑢

Answer 43

LRFD

Question 44

the service loads are generally not multiplied by load factors or safety factors -loads are summed up, as is, for various combinations, and the largest values obtained are used to compute the forces in the members

Answer 44

ASD Load Combinations

Question 45

nominal strength of a member safety factor Ω largest computed force in ≥ member, 𝑅𝑢 Or 𝑅𝑛 ≥ 𝑅𝑎

Answer 45

ASD

Question 46

both LRFD and ASD have goals to obtain a numerical margin between resistance and load that will result in an acceptably small chance of unacceptable structural response in general, Ω = 1.5 𝜙 where Ω = safety factor, a number usually greater than 1.0 used in ASD 𝜙 = resistance factor, a number usually less than 1.0 used in LRFD

Answer 46

FACTOR of SAFETY