Abraham Ruper: Structural

billowycookieUrban and Civil

Nov 29, 2013 (3 years and 8 months ago)

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Bradley
Godshalk
: Foundation and Architectural

Abraham
Ruper
: Structural

Kevin
Molocznik
: Fluid Systems

Charles
Borrello
: Building Thermal Systems

Mark Vaughn: Solar Thermal Systems




Introduction



Floor plan layout



House elevation drawings



Foundation analysis



Roof Truss analysis



Hydronic

subsystem analysis



Heat Transfer analysis


Building and Flat Plate Collector



F
-
Chart analysis

Assumptions:

Flexure Strength of concrete is 600 psi

Weight of a house without foundation walls is 20 lb/ft

Soil density at site is 87.23 lb/ft^3

Factor of Safety of 5

Using max flexure strength of concrete at 120 psi after using the
factor of safety, you can obtain a max bending moment of 144000
lb in by the formula
σ
=
Mmax
*c/I, where c is the distance at which
the moment is applied and I is the moment of inertia

Using that maximum
moment in a bending
diagram, you can obtain a
maximum shear value of
1800 lb, which will also
equal the reaction at the
top of the foundation wall

After subbing in the reaction at the top
of the foundation walls into the
equations obtained from summing the
forces in the x
-
direction of the free body
diagram and the moment equation, you
can find the force of the soil on the wall

Using this maximum force, you can sub it into the fluid
mechanics formula for hydrostatic fluid on a solid body, which
is F=
ρ
*w*(d^2)/2, where
ρ

is the density of the soil, w is the
maximum width of the wall without failure, and d is the
distance of the soil, assumed here to be 10 feet, the full
foundation wall length

The maximum length of the wall without breaking made of
pure concrete was found to be 1.24 feet for our 10 inch wall.
It is then every 1.24 feet that rebar will be placed to handle
the bending moment. For an extra factor of safety, rebar can
be placed at every 1 foot.

There are two different types of foundation walls that can be
used for this foundation.
Masonary

wall, which is cement blocks
bonded together with mortar with rebar placed in the hollow
core, or a poured cement wall with rebar placed inside the
poured cement. Each type will require rebar at about the same
interval, about 1 foot. The costs will be comparable to each other
for installation, depending on the contractor. The advantage in
the long run however is clearly poured concrete, as it has a much
higher insulation value, which will reduce the amount of energy
used for space heating. This can save a significant sum of money
over the life of the home.

The allowable bearing pressure that can be placed on the soil
according to the Salt Lake City building codes is 1500 lb/ft^2.
By dividing the approximate weight of the house and foundation
walls, 70,000 lbs, by the perimeter of the foundation, we can
come up with that the footers should be about a foot wide to
handle the load safely.

Waterproofing should also be looked into for the area and the
site that this house is to be built on. Options include plastic
sheeting on the outside of the foundation walls and tar on the
outside of the foundation walls.

Gambrel Truss

Common Truss

+
Customer

preferred style

+
Less area for snow to build up
around

-
Custom design increases cost
and order to delivery time

-
Some usable living area is lost
due to vertical truss supports

-
truss must help rafters support
living weight on lower member



+
Standard

design allows for
option of ordering prefabricated
trusses to decrease cost

+
Prefabricated trusses use better
materials and indoor assembly
assures

-
Roof aesthetically similar to
other homes and not style
customer requested


Givens/Assumptions:

-
1 truss every 2’ (25 total)

-
Southern pine 2x12’s

-
Southern pine:
ρ
=37 ft/lb
3
,
σ
b max
=1.56x10
6

lb/ft
2
, E=2.8x10
8

lb/ft
2

-
Factor of safety = 5

-
Roof pitch: 65
°

lower section, 40
°

upper section (FPC location)

-
Allowable normal stress=1.66x10
5

lb/ft
2

-
Allowable bending stress=3.12x10
5

lb/ft
2


Loading Conditions

Roofing Material
-

3.8 lb/ft
2

Total FPC
-

25 lb/ft
2

(upper section only)

Snow
-

42.5 lb/ft
2

(upper), 5 lb/ft
2

(lower)

Living
-

20 lb/ft
2

Loading in members:

BC = CD = 855.7 lb in Tension

AB = DE = 1310.9 lb in Tension

AE = 554 lb in Compression


Normal stress in members:

(allowable 166,000 lb/ft
2
)

BC = CD = 7143 lb/ft
2

(ok)

AB = DE = 10943 lb/ft
2

(ok)

AE = 4625 lb/ft
2

(ok)


Bending stress in members:

(allowable 312,000 lb/ft
2
)

BC = CD = 5,240,000 lb/ft
2

(X)

AB = DE = 6,460,000 lb/ft
2

(X)

AE *= 11,500,000 lb/ft
2

(X)



Gambrel style achievable but
extra supports needed will take
some 2
nd

floor living space


*some of living weight will be
supported by rafters

Layout
: The hot water storage tank will be located in the basement and piping will


run up through the house through the bathrooms on each floor to the roof and FPC’s


to minimize pipe lengths and keep piping neatly tucked away.


Pipe/Fluid Selection
: CPVC


Like PVC but designed for hot water applications


50/50 Water Glycol mix for fluid.


Pump Selection
: 8249K52 from the McMaster
-
Carr catalog, or 2 smaller circulating


pumps if a smaller, quieter, more economical pump is desired over a robust one.


Hot Water Storage & Heat Exchanger
: Caleffi Solar Water Heater Tank (119 gallons)


It has a built in heat exchanger and small back up heater if supply of hot water


is exhausted.


Head value for pump
: With current values 32 feet


Misc
:

-
Considering adding insulation to piping, low cost/easy install


-
Components such as valves, fittings, elbows, can all be purchased


off McMaster
-
Carr

-
It is not feasible to try to harness geothermal benefits in SLC



CPVC

Copper

+Resistant to corrosion

+Smooth

bore = less noise

+Cheap

+Easy Installation

+Lightweight

+Eliminates water hammer

+Unaffected by corrosives in
waster that copper are affected
by

-
Supports bacteria growth

+Durable

+Does

not support bacteria
growth

+smaller pipe sizing available

+joints aren't bulky

-
More expensive

-
Greater thermal loss over CPVC

-
Prone to be louder than CPVC
when water is running at high
velocities through the piping

Section

Inputs

Outputs

Flow Rate

F.R.
adjusted

Pipe
Diameter

Velocity

Friction Head Loss

Pipe
Length

# of
Equivalent
Elbows

Equivalent
Length Per
cell

Total Equiv Pipe
Length of
Elbows

Total Equiv Pipe
Length of pipe +
Elbows

Pipe
Losses

Elevation
Out
-

Elevation In

Other
Losses

Total
Losses

Culmative

Head

(
-
)

(
-
)

(gpm)

(gpm)

(inches)

(ft/sec)

(ft head / 100ft of
pipe)

(ft of pipe)

(# ells)

(ft of pipe/ell)

(ft of pipe)

(ft of pipe)

(ft head)

(ft head)

(ft head)

(ft head)

(ft)

Pump

A

B

0.7

0.84

0.75

0.5

3

1

0

1

0

1

0.03

0

0

0.03

0.03

Control Valve

B

C

0.7

0.84

0.75

0.5

3

3

2

1

2

5

0.15

0

0

0.15

0.18

Riser Pipe

C

D

0.7

0.84

0.75

0.5

3

45

2

1

2

47

1.41

30

0

31.41

31.59

Collector Inlet Pipe

D

E

0.7

0.84

0.75

0.5

3

5

2

1

2

7

0.21

0

0

0.21

31.8

Flat Plate Collector

E

F

0.35

0.42

0.75

0.5

1.5

9

0

0.5

0

9

0.135

8

14.6

22.74

54.535

Reverse Return
Pipe

F

G

0.35

0.42

0.75

0.25

1.5

5

4

0.5

2

7

0.105

0

0

0.105

54.64

Roof Pitch Pipe

G

H

0.35

0.42

0.75

0.25

1.5

3

1

0.5

0.5

3.5

0.053

-
8

0

-
7.948

46.693

Drop Pipe

H

I

0.35

0.42

0.75

0.25

1.5

31

1

0.5

0.5

31.5

0.473

-
30

0

-
29.53

17.165

Isolation Valve

I

J

0.35

0.42

0.75

0.25

1.5

1

0

0.5

0

1

0.015

0

0

0.015

17.18

Heat Exchanger

J

K

0.35

0.42

0.75

0.25

1.5

4

20

0.5

10

14

0.21

0

15

15.21

32.39

Isolation Valve

K

A

0.35

0.42

0.75

0.25

1.5

1

0

0.5

0

1

0.015

0

0

0.015

32.405

*flow Increased %20 for %50 glycol/water mix

Fluid
-

There are 127 days in SLC where temps drop below freezing. Also the record lows hit
-
30F. Therefore a mix of glycol and water
(50%) will
be used in the piping running from the FPC to the Heat Exchanger. With this mixture we still retain some of the benefits of
usi
ng water, while
gaining the benefits of glycol and not have to worry about water freezing in the pipes. *Flow must be increased %20 for a 50/
50
glycol water
mixture when compared to water.


Pipe sizing
-

Flow rate is one major factor that governs pipe sizing. The less flow you have the smaller the piping you need. Our system ha
s

a
particularly low flow so were going to go with ¾” piping.


Pump Selection
-

8249K52 from the McMaster
-
Carr catalog, or 2 smaller circulating

. Both options will cover the need flow rate and head. The trade offs are that the smaller pumps are quieter, more economical
. B
ut they are not as
robust and will most likely require more maintenance.


Hot Water Storage & Heat Exchanger
: (NAS20123)
Caleffi

Solar Water Heater Tank (119 gallons)


It has a built in heat exchanger and small back up heater if supply of hot water


is exhausted. 119 gallons was chosen after comparing various average water usages in homes. Very heavy hot water usage in fam
il
ies of 2
adults and 2 children were in the 119 gallon area. Average hot water usage varied from 60 to 80 gallons a day.






http://www.flasolar.com/pipes.php

<
-----
pipe selection

http://www.flasolar.com/active_dhw__heat_exchange.php <
-----
ditto

http://geoheat.oit.edu/toa/toa5task2.pdf <
----

study on geothermal
feasability

of SLC

http://www.builderswebsource.com/techbriefs/cpvccopper.htm#Introduction <
----
plumbing selection

http://www.aceee.org/consumerguide/waterheating.htm

http://www.siliconsolar.com/solar
-
water
-
storage
-
tanks.html

http://www.eagle
-
mt.com/radiantmax/indirect_tanks.php


http://www.bamsolarpower.com/solarwaterheater.html

http://www.mcmaster.com/#cpvc
-
drinking
-
water
-
pipe
-
fittings/=43qw8i <
-
pipe fittings

http://www.engineeringtoolbox.com/ethylene
-
glycol
-
d_146.html <
-
sizing water glycol

http://www.engineeringtoolbox.com/pvc
-
pipes
-
friction
-
loss
-
d_803.html <
-

friction loss of water
in
pvc


http://harvelsprinklerpipe.com/harvel/pdf/friction
-
loss
-
tables.pdf

<
-

friction loss of water
in
cpvc


http://www.mcmaster.com/#8249k52/=455ks4 <
-
pump sized

http://www.sssolar.com/Caleffi_Solar_SolarCon_solar_water_heater_tank_tech_specs.pdf

http://www.pipeflowcalculations.com

<
-

various useful calculators


Wall construction


Drywall (5/8’’)


Interior film (still air)


Foil faced insulation and air gaps 85% of wall
area


Studs (2’’x6’’) 16’’ OC, 15% of wall area


Plywood (3/4’’)


Foil faced sheath


Exterior film (
avg

wind speed: 8.8mph)


Siding


Other construction materials


Windows ≤15% of wall area


Doors <5% of wall area


Concrete, poured or blocks


Thermal gradient: Tin=70
°
F Tout=10
°
F


I.
Options

A.
Wall versus windows

1.
Buy better windows (low U
-
value) and insulate the walls
less.

2.
Buy decent widows and heavily insulate the walls.

* U
-
value for windows must be ≤.3 in order to get energy tax
credit of $1500

B.
Floor versus basement

1.
Insulate the first floor thus excluding the basement from
the thermal envelope

2.
Do not insulate the first floor, and assume the concrete
form of the basement will suffice for insulation.

C.
Gambrel roof versus standard roof

1.
This is not the option of the Building Thermal Engineer but
it does affect the heat transfer analysis.

R
-
values in [hr*ft^2*
°
F/BTU]


WALL

floor

ceiling

Between Studs

At studs

Between Studs

At studs

Between Studs

At studs

drywall

0.56

0.56





0.56

0.56

interior film

0.68

0.68









insulation and air gap

7

0

8.24

0

21.1

0

studs

0

6.88

0

11

0

6.88

plywood

0.94

0.94

0.94

0.94





sheath

10.8

10.8









exterior film

0.17

0.17









siding

1.8

1.8









TOTAL R

21.95

21.83

9.18

11.94

21.66

7.44

TOTAL U

0.045558087

0.04580852

0.108932462

0.083752094

0.046168052

0.134409

R
wall
=

21.932

R
floor
=

9.594

R
ceiling
=

19.527

U
wall
=

0.045595652

U
floor
=

0.105155407

U
ceiling
=

0.059404



U
-
Value

standard roof Areas ft^2

gambrel areas ft^2

walls

0.045595652

2175

2315

Windows

0.3

400

400

doors

0.066666667

126

126

roof

0.059404134

1296

940

floor

0.105155407

1296

1296

basement

0.5

2496

2496

T
in

[
°
F]

70

T
out

[
°
F]

10

Envelope includes:

area

U
-
value

U*A

q

Q

floor

5293

0.083

440.84

5.00

26450.38

floor & gambrel

5077

0.083

419.69

4.96

25181.51

basement

6493

0.239

1552.56

14.35

93153.50

basement & gambrel

6277

0.244

1531.41

14.64

91884.63

units:

ft^2

BTU/(hr*ft^2*
°
F)

BTU/(hr
°
F)

BTU/(hr*ft^2)

BTU/hr


subject to change


*source http://www.coloradoenergy.org/procorner/stuff/r
-
values.htm


Best Case Scenario
-

House U value of 412.6 BTU/hr
-
F


42.6% of the homes energy needs will be met by the FPC array with 5 solar collectors and a life cycle
savings of $8761, and life cycle cost of $3081 for equipment and $15957 for additional heating bills.



Worst Case Scenario

-

House U value of 496.59 BTU/hr
-
F


38.2% of the homes energy needs will be met by the FPC array with 5 solar collectors and a life cycle
savings of $8976, and life cycle cost of $3081 for equipment and $19489 for additional heating bills.



The water temperature for these values was set to 125 deg F with 120 gallons used per day, and an
environmental temperature of 70 deg F. Conventional heating was provided by electricity because it was
the cheapest of the alternative heat sources.



The FPC units that were used for this simulation were 21.5 square feet in aperture area and an estimated
cost per unit area of 37 $/ft^2, and oriented at an angle of 40deg from horizontal.



These values and costs can be changed by an increase in the homes overall insulation, as well as the
addition of more collectors, however the number of collectors is limited by the area of the roof, and the
roof trusses ability to support their weight. A lower estimate of hot water usage would also result in a
more efficient system, as would lowering the temperature of the water. Another option would be to
remove either the DHW or heating option.