Chapter 2 Concept Questions

What is the basic wind speed, V, for an occupancy category II building in Salt Lake City, Utah?

115*

In ASCE 7-10 the velocity pressure coefficient Kz for MWFRS on a 25 ft structure can be determined from either a table or the equation _______.

2.01(z/zg)^2/alpha*

The wind provisions previously contained in Chapter 6 of ASCE 7 are now found in what chapters?

26 through 31*

The basic wind speed, V, can be read from maps of the U.S. given in ASCE 7-10. These basic wind speeds are based on _______.

3-second gust wind speeds

The design lateral soil pressure for poorly grade clean gravels is _______. Refer to ASCE 7 if necessary.

35*

The Live Load Element Factor, KLL, for exterior columns without cantilever slabs is _____.

4*

The minimum uniformly distributed live load for helipads is _____ psf.

60*

In wood frame buildings, the main wind force-resisting system (MWFRS) most commonly consists of which of the following elements?

All of these choices, shear walls, floor diaphragms, roof diaphragms

For roof members, the equation Lr = L0R1R2 is utilized to determine the reduced roof live loads, where L0 = unreduced roof live load, AT = tributary area, and F = slope (in/ft). However, this equation can be reduced to Lr = L0 when _______.

At =< 200ft^2 and F =< 4*

Some wood members, such as glulam beams and wood trusses, may have curvature built into the member while it is manufactured. This built-in curvature is known as _______.

Chamber*

Which of the following are ASD basic load combinations? Select all that apply.

D, D + L, 0.6D + 0.7E*

_______ loads consist of the weight of all materials of construction incorporated into the building including, but not limited to, walls, floors, roofs, ceilings, stairways, built-in partitions, finishes, cladding and other similar incorporated architectural and structural items, and the weight of fixed service equipment.

Dead*

In regards to the components and cladding (C&C) calculations, which of the following choices does not represent a surface discontinuity (i.e., a change in the geometry of a structure)?

Doorways*

Experience from previous earthquakes indicates that certain types of LFRSs perform better than others. This better performance can be attributed to the _______ of the system.

Ductility

Dead loads are the weights of all materials permanently attached to the structure and are typically expressed in lb/ft or psf. Is the dead load in psf of a framing member that uses 2x12 beams weighing 5.40 lb/ft at 16" o.c. equal to 7.20 psf?

False

In ASCE 7-10, the simplified envelope approach to calculating wind pressures for components and cladding is applicable only for enclosed low rise structures.

False

The tributary area typically includes the full area of all members that are supported by the member under consideration.

False

Typically FP will be considered in two perpendicular horizontal directions, combined with a vertical force component.

False

When determining design wind pressures using the envelope method, it only applies to partially enclosed and enclosed structures.

False

Construction starts with the lightest framing member on the top level and proceeds downward, and design starts at the bottom with the largest members and proceeds upward.

False*

Earthquake forces are caused by the constant velocity of the building's mass.

False*

IBC Sec. 1612 refers the user to ASCE 26 for design and construction requirements for flood loads in flood hazard areas.

False*

Loads for which the magnitude is constant are termed transient loads.

False*

Snow importance factors are not a function of a building's risk category.

False*

Snow is likely to blow off a sheltered roof.

False*

The "2a" dimension found in ASCE 7 Fig. 28.6-1 used to locate the end zone loads is measured from the edge of the corner-roof-overhang when available.

False*

The important differentiation for most wood structures is that the vertical portion of the load is generally carried by sheathed shearwalls, while loads acting laterally are carried primarily by systems of joists, beams, and posts or walls.

False*

The symbol F is used for calculations involving flood loads or hydrostatic pressure.

False*

The two procedures used to determine wind loads for the main wind force-resisting system (MWFRS) are the deflection method and the low-rise method.

False*

When calculating the wind forces acting on a structural element using the main wind force-resisting system (MWFRS) pressures, the wind pressure formula pnet = λKztpnet30 can be used.

False*

When determining the snow exposure factor, Ce, for buildings with more than one roof, ASCE 7 intends for the roof exposure category to be selected based on the worst-case roof of the building.

False*

Snow accumulation on the ground is less than at the roof level for most structures.

Flase*

On a roof that is relatively _______ , fairly _______ unit live loads are likely to occur. Select all that apply.

Flat, high and steep, low*

The load due to the weight of water in an elevated water tank would be considered a _______ in the ASCE 7 load combinations.

Fluid load (F)

_____ is the symbol used for lateral soil loads, loads due to hydrostatic pressure, and the pressure of bulk materials.

H*

_______ is parallel to the short dimension of the building.

Horizontal lateral force, Transverse lateral force

The majority of wood-frame buildings are designed using which approach?

Linear dynamic behavior

The majority of wood-frame buildings are designed using which approach?

Linear static analysis*

A load produced by the use and occupancy of the building or other structure that does not include construction or environmental loads is a _______.

Live*

The concept of rain load is primarily applicable to _______.

Low slope roofs*

Structural design criteria can be divided into which two main groups? Select two.

Serviceability and strength checks

_______ is described as "very dense soil and soft rock."

Site Class C*

_______ is described as "very dense soil and soft rock."

Site class C

In design of snow loads, several factors are considered. Which one of the following factors does not influence snow loads?

Snow speed factor

_______ is the term used to refer to the amplification of earthquake effects caused by soil conditions.

Soil structure resonance*

Which of the following is NOT one of the five criteria that must be met in order to require an evaluation for a topographical factor other than 1.0, according to ASCE 7-10?

The height of the feature is less than 60ft for exposure B and 15ft for exposure C*

The failure of a roof due to ponding is related to _______.

The water soaking into the roofing material and causing damage

The formula for Fx will produce a _______ distribution of horizontal story forces if the masses assigned to the various story levels are equal.

Triangular*

A building is to be located at the top of a 150-ft-high hill. The hill is 5 times as high as any other obstruction within 3 miles. The slope of the top half of the hill is 1:8. In this case, the topographical factor Kzt can be assumed to equal 1.0.

True

A sheltered roof is a roof located tight in among conifers that qualify as obstructions.

True

Experience from several earthquakes has shown that local soil conditions can have a significant effect on earthquake response.

True

It is possible to avoid hydrostatic pressure on retaining walls by providing drains behind them

True

Most structures will need to be designed for dead load, live or roof live load, rain, and snow load as a minimum. Other loads that are not applicable to the structure can be crossed off in appropriate load combinations.

True

Roof slope factor accounts for the likelihood of snow sliding to the ground from a sloped roof.

True

Snow importance factors increase with decreasing risk category.

True

The concept of rain load is primarily applicable to low sloped roofs.

True

The tributary area is the area that is assumed to load a given member. The tributary width, wT, is the width the span of the member supports. With a known length, L, for a given member, the tributary area AT = 2wTL.

True

The two primary types of wind loads are the main wind force-resisting system (MWFRS) pressures and the components and cladding (C&C) pressures.

True

The two procedures used to determine wind loads for the main wind force-resisting system (MWFRS) are the directional method and the envelope method.

True

The type of live load, uniform or concentrated, which produces the more critical condition in the required load combinations should be used in sizing the structure.

True

1.2D + 1.0E + L + 0.2S represents one of the LRFD load combinations.

True*

A fully exposed roof occurs when roofs are exposed on all sides without shelter from higher terrain, mechanical equipment, or conifer trees with leaves in the wintertime.

True*

ASCE 7 Chap. 13 addresses the design of components attached to the structure.

True*

Design snow loads are on a horizontal plane.

True*

IBC deflection criteria may not provide a sufficiently stiff wood floor system for certain types of buildings.

True*

If a member has a small area contributing live load, it is likely that a fairly high unit live load will be imposed over that relatively small area.

True*

In wood structures, the dead load of the framing members is a fairly minor portion of the total design load, so a small error in estimating the weights of framing members typically has a negligible effect on the final member choice.

True*

Loads caused by fire-fighting equipment may be included in roof live load calculations.

True*

Metal roofing is considered an unobstructed slippery surface.

True*

Prescriptive construction is primarily intended for one and two family dwellings.

True*

Proximity to discontinuities on the surface of a structure affects the magnitude of components-and-cladding pressures.

True*

Self-straining loads primarily occur due to dimensional changes of the structural element or movement of the support for the member. Where members are free to move with dimensional or support change, forces do not develop. Where elements are restrained against movement, dimensional or support change will induce internal stresses.

True*

Snow is likely to blow off an exposed roof.

True*

Snow load is a type of gravity load that primarily affects roof structures, balconies and decks.

True*

The unit live loads specified in ASCE 7 and the IBC are applied on a horizontal plane.

True*

Thermal factors greater than unity are specified for structures where snow is unlikely to melt from the roof.

True*

Unit snow loads cannot be reduced, unlike roof live loads.

True*

When determining the snow exposure factor, Ce, for buildings with more than one roof, ASCE 7 intends for the roof exposure category to be separately selected for each roof of the building.

True*

The simplified design wind pressure (Ps30) for the main wind force-resisting system (MWFRS) is a function of which of the following? Select all that apply.

basic wind speed and region or zone

ASCE 7 Sec. 12.10.1.1 specifies that the redundancy factor _____ is to be used in the design of diaphragms for structures assigned to SDC D, E, and F.

p*

Rain load R is calculated as R = 5.2 (ds + dh). Given that ds is depth of water and dh is additional depth of hydraulic head, what is the unit of measurement for R?

psf*