Structural Analysis
ARMWOOD, CATHERINE 1

ASSIGNMENT #3: STRUCTURAL LOADS: PART 1

Due Friday 9/4/2020 by 11:59pm.

1. For problems 1a-1b given the loads specified, calculate the maximum load using ASCE 7-10 load

combinations for allowable stress and strength design. In solving these problems, for full credit,

I should see your calculations for all conditions before you specify the worst case.

a. D = 50 psf, Lr = 75 psf, R = 8 psf, and S = 20 psf.

b. D = 13 k, L = 32 k, W = ?22 k, Ev + Eh = 16 k, and ?Ev + Eh = ?16 k. (When doing strength

design assume L comes from a live load less than 100psf)

2. Based on preliminary estimates and the architect’s design, a team member has developed the

anticipated cross-section for an office floor. The plan is to use cinder concrete, which is also

called lightweight concrete. What is the unfactored dead load pressure for the anticipated floor

cross-section?

3. To design the floor of a building, we need to know the load created by the walls. For this

building, the walls are considered fixed partitions (they will not be moved around by

renovations). What is the unfactored line load generated by the self-weight of the wall?

ARMWOOD, CATHERINE 2

ASSIGNMENT #3: STRUCTURAL LOADS: PART 1

4. The architect has laid out the anticipated functions for a new library: offices, reading areas,

stack areas, and corridors. The open layout of the upper floors, however, means that the entire

layout could be reconfigured at a later time.

a. What are the minimum unfactored live loads for the offices, reading areas, stack areas,

and upper floor corridors?

b. How can we account for the layout changing over time? Why is that a reasonable

choice?

ARMWOOD, CATHERINE 3

ASSIGNMENT #3: STRUCTURAL LOADS: PART 1

5. A construction company wants to use a truss to hold equipment over the edge of a building

during construction. The maximum likely, unfactored dead and live loads have been calculated.

To properly design the locations where the truss will attach to the building, we need to know

the design reactions.

a. What is the design vertical reaction at A? Provide values for both upward and

downward reactions.

b. What is the design vertical reaction at B? Provide values for both upward and downward

reactions.

ARMWOOD, CATHERINE 4

ASSIGNMENT #3: STRUCTURAL LOADS: PART 1

6. We are designing a concrete retaining wall for a dolphin tank at the new zoo. We need to know

the peak design moments at the base of the wall in order to begin design of the wall. The

geotechnical engineer recommends that we consider this soil pressure to be based on a density

of 45 pcf. Caretakers at the zoo have given us the ideal salinity of the water for the dolphins;

with a bit of research, we estimate the resulting density of the water to be 64.1 pcf.

a. What is the design counterclockwise moment? What load factors and combination give

that design value?

b. What is the design clockwise moment? What load factors and combination give that

design value?

ARMWOOD, CATHERINE 5

ASSIGNMENT #3: STRUCTURAL LOADS: PART 1

7. We want to design a reinforced concrete beam that overhangs the supports on both ends. To

design that beam, we need to know the design moments, both positive and negative, at

midspan (point B). Remember that live load can act everywhere, somewhere, or nowhere.

ARMWOOD, CATHERINE 6

ASSIGNMENT #3: STRUCTURAL LOADS: PART 1

8. Our team is designing a new highway overpass. Although we have not completed the design of

this overpass, the geotechnical engineer needs a preliminary estimate of the design vertical

force and the design moment that the foundation must carry. At this time, we estimate that the

maximum likely, unfactored dead load from each girder is 40 kips and the live load is 20 kips. For

this situation, we need only the largest-magnitude design moment rather than both positive and

negative moments. Remember that the moment is calculated at the neutral axis. Note that

although AASHTO load factors and combinations would govern this design, we will use the ASCE

7 load factors and combinations for this preliminary analysis, since they are handy.

ARMWOOD, CATHERINE 7

ASSIGNMENT #3: STRUCTURAL LOADS: PART 1

9. The roof of the building is flat. It is composed of 2 in. of reinforced concrete on 18-gauge metal

decking that weighs 3 psf. A single-ply waterproof sheet of 0.7 psf will be used. The ceiling

beneath the roof is unfinished, but allowance for mechanical ducts should be provided.

Determine

a. The roof dead load

b. The roof live load in psf to be applied to column A1

10. Determine the dead load and live load for a typical upper floor in an office building with

movable steel partition walls. The ceiling below is a suspended steel channel system (2 psf) and

the floors have a linoleum finish. The floors are 3-in. reinforced concrete. Allowance should be

provided for mechanical ducts.

11. Determine the design rain load on the roof of a building that is 250-ft wide and 500-ft long. The

architect has decided to use 6-in. diameter drains spaced uniformly along the long sides of the

building at 40-ft intervals for the secondary drainage system. The secondary drains are located

1.5 in. above the roof surface (primary drain). The rainfall intensity at the location of this

building is 2.5 in. per hour.

12. A new auditorium is being built in a region where the ground snow load is 75 psf. The

surroundings of the building site can be classified as an exposure C with partial shelter. It is

adequately insulated and kept well above freezing. What is the flat roof design snow load, in psf,

that should be used for this building?

ARMWOOD, CATHERINE 8

ASSIGNMENT #3: STRUCTURAL LOADS: PART 1

13. A convenience store is to be built in New Orleans, Louisiana (latitude = 29.97°, longitude =

?90.06°) in a location that could be classified as an exposure C. Calculate the design wind

pressures for the MWFRS of the building for the wind direction shown in the accompanying

figure. Provide a sketch of the wind pressure zones, see example 8 in the Lecture Notes.

14. For the ordinary steel moment frame (R = 3.5) structure shown, calculate the equivalent seismic

loads that should be applied at all levels (F2, F3, and Froof). The structure will be used as an office

building and will be located in Atlanta, Georgia (latitude = 33.75°, longitude = ?84.39°) where

the soil type is classified as a type D.