Transfer of 2nd story shear to 1st floor

[civilgene]

Hello All,
I have a small residential addition to a wood framed structure. I need to transfer 2100# of shear from a 2nd story wall to a strongwall on the first floor. The catch is the strongwall is located 7' over (laterally)from the 2nd story wall. The strongwall will handle the additional shear, I just need to get it there. Any ideas? Have you heard of the building dept (Southern Calif) allowing straps? Any ideas are appreciated.
Thanks.

 

[SperlingPE]

Check your floor for diaphragm capacity.
Attach upper wall to floor to floor to handle load. don't forget overturning.
If floor is not adequate add framing members, straps, ties, braces, etc. to get load to strong-wall.
Basically provide load path for lateral load.

 

[LGARG]

HI, I think that you should take the shear form above with a Drag or blocking. you have to calculate the lenght of blocking needed to transfer the shear from the shearwall to the diaphragm ( Shearwall force / Diaphragm capacity = Length of blocking or Drag w/ boundary nailing needed). if you have uplift form above (shear from second level* Second level height) you have to calculate the holdowns w/ omega factor plus 1.4(strengh level design so you could increase your capacity in 1.7).The holdowns at the first floor should be calculated with((Shear from above+shear from this level)*First floor Height).The diapraghm should take the load from above and the load from this level. I dont remember but i think that the drag or collector must be calculated with the omega factor too.

 

[RareBugTX]

There is a good example regarding this issue in the Tiber Solutions Manual.Look it up on the Shearwall Chapter.

http://www.iccsafe.org/e/prodshow.html?prodid=9149s00&stateInfo=NZanfknbcPdjAicd8717|2

Regards

 

[RARWOOD]

What you have is either a shear wall with a horizontal offset or a shear wall with an in plane offset. If the strong wall is offset 7' perpendicular to your shear wall then it is a horizontal offset.

With a horizontal offset the base shear from the 2nd story wall is applied as a concentrated load to the first floor diaphragm. You may need a drag strut in line with the 2nd story wall in order to transfer the shear force into your first floor diaphragm. You also must have columns under the 2nd story wall chords to transfer the chord forces into the foundation. This could also be down by using a beam under the shear wall.

 

[Disx]

What is under the 2nd story shear wall? - I assume nothing, ofcourse. But as RARSWC eluded to, can you fit in two columns underneath the 2nd story shear wall to pick up the chord forces?

If there is no space for columns then could you place a beam in place of the rim, connect the 2nd story shear wall into that beam, and design that beam with a couple located at the center of that shearwall? Then have pin connections from the timber beam to the foundation?

I ask myself because I have a similar project where pretty much none of the 2nd story walls are inline with the 1st (in plane, horizontal offset).

 

[NYSCEO]

Hello to all the SE and PE. Please let me introduce myself. I am a NYS Certified Municipal Code Enforcement Official. I have a Degree in Architectural Technology. I have worked in architectural firms doing design build and structural design upto 1991. Since then I am working in the local building department reviewing plans. Since NYS adopted the IBC in 2003, structural compliance has turned into a nightmare. I have read this site many times and the information all of you are discussing is invaluable. Today however, I would like to ask for advise. I deal strictly with commercial buildings and the BCNYS which is close to the IBC. Today, I came across a set of plans for a new 3 story wood framed structure. Story 2 and 3 are set back from story 1 wood bearing walls and are inturn supported on a steel beam and column frame. Story 3 is within the roof. Story 2 exterior wood stud walls and floors are carried by the steel beams and story 1 roof rafters are sheds which rest on all wall sides of story 2. The plans and calculations address shear walls ONLY on story 1. The designer has stated that shear on second story is "neglidgible" and is "contained" by the shed roof of story one. How this works is not detailed. Story 2 has no hold downs, collector design or sole plate shear attachment, so CLP is questionable. Shear wall deflections have not been shown. Roof and foor diaphragm design is not provided. The designer states on plans that story 1 front elevation was worst case and all shear walls designed as perforated. Checking calculations and shear wall elevation, shear wall segments are shown with hold downs on the sides of EACH one. I believe that these are segmented walls. Also, segment height to width ratios are 9.33 feet high with smallest width of 2.67 feet. Calculations submitted were by computer method from "ENERCALC". Chapter 22 compliance was not provided, so steel detailing for seismic is not shown. Compliance with 1605, 1603, 1609, 1615-1620 and 2301 were not provided. As an unofficial opinion from the group, does this presented theory seem in compliance with the Building Codes? True, you do not have the papers in front of you, but frankly as a Code Official and discussing compliance with the design professional and supplying many shear wall design guide lines I just cant accept this. Off the record comments please. Thanx all and kudos on a great forum.

 

[csd72]

NYSCEO,

You should start a new thread on this one. It is considered impolite to ask a question that is not directly related to the original post.

Go to the start page and pick 'start a new thread".

Welcome to the forum

csd

 

[NYSCEO]

OOpps, my apologies.

since i am new to this site i will learn protocol.

now, if i can just find where "stat thread is"!