Riverton City Steel Framed Structure

closedlavenderΠολεοδομικά Έργα

25 Νοε 2013 (πριν από 3 χρόνια και 10 μήνες)

83 εμφανίσεις

Riverton City Steel Framed Structure

We

used

AutoDesk

Revit

to

model

the

structure
.

We

also

created

approximate

models

of

the

salters

to

get

an

idea

of

how

they

would

look

in

the

structure
.


Riverton

City

Public

Works

moved

to

a

new

location

and

requested

the

design

for

the

relocation

of

a

steel

framed

structure

to

store

their

snow
-
plow

salters

during

the

summer

months
.

While

the

structure

would

be

rebuilt

as

before,

it

was

requested

that

(
4
)

additional

beams

(referred

to

as

salter

beams)

be

added

to

support

(
4
)

3
.
1

kip

snow

plow

salters
.

Considering

the

additional

weight

of

the

salters,

it

was

also

required

that

the

footings

be

re
-
designed

to

support

the

new

loads

and

that

the

existing

beams

and

columns

be

analyzed

to

verify

that

they

could

support

the

new

weight
.

The

purpose

of

the

structure

is

to

allow

the

snow

plow

trucks

to

back

into

the

structure

with

the

new

steel

beams

in

place

and

still

be

able

to

easily

load

the

salters

on

the

truck
.


After

demands

for

the

critical

beams

and

columns

were

calculated

by

hand

and

verified

by

StruCalc
,

the

footings

for

the

new

structure

were

designed
.

The

square

footing

design

can

be

seen

in

the

detail

below
.

The

footings

were

also

designed

for

the

possibility

that

the

snow

plow

truck

drives

over

the

top

of

the

footing
.


We

decided

early

on

that

we

would

choose

a

W
8
-
shape

beam

to

support

the

salters

since

this

shape

would

fit

nicely

inside

the

flanges

of

the

girder,

making

for

easier

construction
.

Our

final

recommendation

for

beam

size

is

a

W
8
X
21
.

Thi s

beam’s

capaci ty

meets

al l

of

the

demands,

as

seen

in

the

table

below
.

The

shape

of

the

salter

beams

was

decided

after

consulting

Michael

Hunsaker

at

PDM

Steel
.

Here

we

learned

which

shapes

were

most

common

and

therefore

cheapest
.

W
-
shapes

proved

to

be

the

cheapest

at

$
0
.
38

per

pound,

while

HSS

started

around

$
0
.
50

per

pound
.

Table

4
,

provided

below,

shows

the

overall

cost

of

new

materials

and

labor
.

By

our

estimates,

the

project

may

cost

less

than

$
2000
.

Limiting States

Demand

Capacity

Yielding [kip
-
ft
]

23.6

76.5

Lateral Torsional
Buckling [kip
-
ft]

23.6

25.4

Shear [kip]

2.70

62.1

Deflection [in]

<0.82

0.67

Material

Size

Length/Volume

Quantity

Total Cost ($)

Weld for salter beam

3/16"

6"

16

68.16

Weld for baseplate

1/4"

sufficient

6

20.00

W8x21

W8x21

15'

4

781.38

Rebar

#4

30"

36

122.40

Concrete

36"x36"x30"

22.5 ft
3

6

450.00

Anchor Bolts

1/2"

7"

24

40.32

Labor

-

-

-

230.00

Grand Total

$1712.26

To

connect

the

salter

beams

to

the

girders,

Riverton

City

Public

Works

requested

a

weld

connection
.

S i n c e

t h e

s a l t e r

b e a ms

f i t

n i c e l y

w i t h i n

t h e

f l a n g e s

of

the

girders,

we

have

specified

two

6


long

web
-
to
-
web

3
/
16


fillet

welds

for

each

salter
-
girder

connection
.

T h e

d e ma n d s

we r e

l e s s

t h a n

3

k i p s

a n d

t h e

we l d

p r o v i d e s

a

50

kip

capacity
.

If

desired,

welds

only

2


long

will

still

exceed

the

demands

by

14

kips
.

Using

AutoCAD,

we

created

plans

for

the

structure

so

that

construction

of

the

footings

and

the

addition

of

the

salter

beams

could

go

as

smoothly

as

possible
.

To

design

the

most

cost
-
efficient

structure,

we

needed

to

explore

several

options
.

Several

options

were

easy

to

rule

out

due

to

cost

of

material,

including

using

HSS

pipes

in

place

of

W
-
shape

for

the

salter

beams
.


A

second

option

was

to

flip

the

two

bays

so

the

original

girders

could

also

act

as

the

salter

beams
.

This

would

cut

out

the

cost

of

the

salter

beams

altogether

and

only

require

slightly

larger

footings
.

However,

since

the

roofing

was

installed

in

one

direction,

the

tin

and

channels

were

already

designed

to

fit

that

direction
.

Changing

this

would

call

for

new

tin

and

channels,

and

could

cost

more

than

adding

four

beams

to

hold

the

salters
.



At

the

request

of

Riverton

City

Public

Works,

we

considered

seismic

design
.

However,

laterally

bracing

the

structure

would

require

cross

bracing

through

the

bays,

which

would

render

them

useless

or

impractical

(as

seen

below)
.

O u r

o f f i c i a l

r e c o m m e n d a t i o n

is

that

seismic

design

not

be

pursued
.

The

demands

on

the

existing

columns

and

girders

were

recalculated

and

the

capacities

exceed

the

demands
.

No

additional

members

are

needed
.

The

final

steel

framed

structure

is

designed

to

support

(
4
)

snow

plow

salters,

two

in

each

bay
.

Each

salter

will

be

supported

by

two

W
8
X
21

beams,

with

a

total

of

(
4
)

beams
.

These

added

beams

wi l l

f i t

snugl y

wi t hi n

t he

f l anges

of

the

existing

W
12
X
40

girders,

which

will

allow

each

beam

and

girder

to

be

welded

web
-
to
-
web

with

two

6


long

3
/
16


fillet

welds
.

Each

footing

has

been

designed

to

withstand

a

demand

of

16
.
2

kips
.

The

square

footing

dimensions

are

3

ft
2

and

30

inches

deep,

to

meet

permafrost

depth

requirements
.