The Simpson StrongTie Catalog

The Simpson StrongTie Catalog

 

This video will teach you how to read the Simpsons Strong-Tie Catalog
and other necessary tables used in seismic retrofitting.

Retrofit components are all rated to resist a certain amount of earthquake force.  Figuring out how much force that will be is the purpose of seismic retrofit engineering.  After figuring out the amount of force to resist, it is a matter of installing enough retrofit components to resist that amount of force.  Doing less than that and there is potential for failure, more than that and you are wasting your money.

Let’s look at this table from a manufacturer’s catalog and see what it tells us.  Reading from left to right the hardware model is a GA1, it requires (4) 10d (a nail with a certain diameter) nails that are 1 1/2 inches long.  F1 means a lateral, as in earthquake force, direction.  Next is the interesting part. DF/SP means this only applies to Douglas Fir (DF) and Southern Pine (SP).  In the column where it says Floor (100), you see the number 235.  This means this hardware can support 235 pounds of floor weight.  In other words, if you have a floor that weighs 235 pounds, you will need one of these to hold it up.

For Wind/Seismic we are told it can resist 330# which is considerably more because it will only need to resist a lateral force for a short period of time versus for a continuous period of time when holding up a floor.

 

 

House Weight and Base Shear

Here are the basics:

• • Determine the weight of the house.
  • Multiply that by 0.186 (g-force)
  • The result is the pounds of force that will be striking the  house on each side.
  • Figure out which and how many retrofit components you will need.

 

Case A:

ROOF: SHNGLES

SIDING: WOOD

WALLS: DRYWALL

 

ONE STORY– 34 psf

 TWO STORY – 29.5 psf 

Case B:

ROOF: SHNGLES

SIDING: STUCCO

WALLS: DRYWALL

 

ONE STORY- 41 psf

 TWO STORY-36.5 psf 

 

 

Case C:  

ROOF: SHINGLES

SIDING: WOOD

WALLS:  PLASTER

 

ONE STORY-45psf

  TWO STORY-41 psf  

Case D

ROOF: SHNGLES

SIDING: STUCCO

WALLS: PLASTER

 

ONE STORY-50psf

TWO STORY-45psf

Case E:

ROOF:  TILE

SIDING: STUCCO

WALLS: PLASTER

 

                                      ONE STORY-60 psf

TWO STORY-100 psf 

 

SHEAR VALUES OF COMMON HARDWARE

 

 

Double Fir Specific Gravity .50,       Old growth (close grain) is .44          New Growth Specific Gravity is .37           .44/.50 = .88               .37/.50 = .74

 

 

    FASTENER                          DOUGLAS FIR                  Close Grain REDWOOD

10d with 1 1/2” penetration	188#	.88 X 188# = 165#
8d toenail 1”    penetration	120#	106#
15 gage staples 1” penetration	45#	40#

 

Bolts in 1½” sill

 

    BOLT                           1 ½”DOUGLAS  FIR             1 ½” Open Grain REDWOOD

½ bolt	1,037#	912#
5/8 bolt	1,485#	1306#

 

Bolts in 2” sill

 

    BOLT                                             DOUGAS FIR                  Close Grain REDWOOD

½ bolt	1213#	1,119#
5/8 bolt	1671#	1,555#

 

 

URFP                                DOUGLAS FIR            Old Growth REDWOOD

1,530#

.88 X 1530# =1346#

 

URFP                                DOUGLAS FIR            New Growth REDWOOD

1,530#

.74 X 1530# =1132#

 

                                                            PLYWOOD

10d Shorts	2” o.c. on edges	870 plf
10d Shorts	3” o.c. on edges	665 plf
8d Commons	2” o.c. one edges	730 plf
8d Commons	3” o.c. on edges	550 plf

 

 

SIMPSON SDS SCREWS

 

                                              DOUGLAS FIR                  REDWOOD

1 1/2”  penetration	300#	.88 X 300# = 264#
2”  penetration	450#	396#
Over 2 ¼” penetration	550#	484#

 

For a discussion on using lag bolts as shear transfer ties please go to our website and watch the video Shear Transfer Ties Using Lag Screws.