2017-1714 Day Residence Revisions Beck.pdfBeck & Associates, PLLC
Structural Engineering & Code Consulting
16425 SE 66th Street, Bellevue, WA 98006 ● beckpllc@msn.com ● PH: 206-313-3739
September 23, 2018
Leif Bjorback
Building Official
City of Edmonds
121 5th Avenue North
Edmonds, WA 98020-3145
Subject: Day Residence Revisions
Permit: BLD17-1714
Per your request, Beck & Associates has completed structural review of the revisions to the
drawings for conformance with the 2015 International Building Code (IBC), as adopted and
amended by the State of Washington (WSA) and the City of Edmonds (ECC).
Our review of the plans and calculations indicates that corrections are necessary prior to permit
issuance. The applicant should address the following comments in itemized letter format in
addition to making corrections & revisions to the drawings. Corrections and revisions to the
drawing should be clouded so that they are clearly identifiable.
The SCOPE of our review is limited to the following items. No aspects of the previously approved
design have been reviewed or verified.
A. Garage Frame (2/S7.0) – removal of steel frame and replacement with wood shear walls
B. Guest Bath Frame (1/S7.0) – removal of steel frame and replacement with wood shear
walls
C. Kitchen Frame South (4/S7.0) – removal of steel frame and replacement with wood
shear walls
D. West Frame (3/S7.0) – Revisions to design
E. Reclassification of Site Class from Site Class D to Site Class C
F. Gym & Kitchen Revisions – installation of new beam (FB14) to open the space in the
basement
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A. Garage Frame (2/S7.0)
1) Reference 2D/S7.0. The detail shows only a single top plate above the garage door. Please
confirm that the single top plate is continuous for the full length of the wall or that a double
top plate is provided. This is required for shear transfer to the garage shear walls below.
Update the plans to provide clarification.
B. Guest Bath Frame (1/S7.0)
2) We take no exception to the proposed revisions.
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September 23, 2018
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16425 SE 66th Street, Bellevue, WA 98006 ● beckpllc@msn.com ● PH: 206-313-3739
C. Kitchen Frame South (4/S7.0)
3) Reference 4C/S7.0.
a) Shear transfer from the shearwall/frame occurs through the plywood on the bottom of
the rafters. Where the rafters are supported by the shear wall, no direct mechanism is
provided for shear transfer other than weak-axis bending of the rafters. Provide a direct
mechanism for shear transfer to the shear wall that does not rely on weak-axis bending
of the rafters. Providing blocking and nailing could be a simple solution.
b) The detail shows only a single top plate along the shear wall. Please confirm that the
single top plate is continuous for the full length of the wall or that a double top plate is
provided. This is required for shear transfer. Update the plans to provide clarification.
4) Reference 4D/S7.0. A hinge-point is created at the column splice. Provide detailing to
demonstrate that the column will be braced within the floor framing system. Identify all
elements. Will the floor sheathing run through the column splice? Is blocking required in
order laterally brace the column at this hinge point? Please address and update the detailing.
5) Reference 4E/S7.0. Specify the required thickness of the column base plate.
6) The glulam ridge beam is shown to bear on the edges of the HSS members. It appears that a
bearing plate is required. Alternatively, provide calculations that demonstrate that adequate
bearing is provided for the glulam ridge beam as it bears along the edges of the HSS vertical
members.
D. West Frame (3/S7.0)
7) Reference page 18 of 198 of the structural calculations provided. The engineer uses a wind
load based on 100 mph ULT (78 mph ASD). However, IBC Figure 1609.3(1) clearly requires
that the design be based on an ultimate wind speed of 110 mph ULT which translates to 85
mph ASD (Eqn 16-3-3 or Table 16019.3.1). Revise the design accordingly. IBC 1609
8) Reference page 19 of 198 of the structural calculations provided.
a) The engineer uses a response modification factor, R, of 3.0 in order to avoid required
detailing per AISC 341-10, Seismic Provisions for Structural Steel Buildings. While a
smaller response modification factor is permitted to be used (resulting in higher seismic
forces), detailing is still required to meet the requirements of AISC 341-10. [Taking the
engineer’s logic to an extreme, one could design a high-rise structure using ordinary steel
moment frames that are not detailed for seismic loads (in lieu of steel special moment
frames) in seismic design category D by simply amplifying forces by 8/3, even though
ASCE 7-10, Table 12.2-1 states that this is not permitted.] Revise the analysis and design
accordingly. ASCE 7-10 Table 12.2-1
b) The calculations state: “Seismic Design Category C per Geotech Eng”. However, the
geotechnical engineer’s conclusion is that the Site Class is C, NOT the Seismic Design
Category. The Seismic Design Category is determined by the short period design
acceleration SDS (= 0.849 for this building) and SD1 (= 0.432 using Site Class C for this
building). Therefore, the Seismic Design Category remains D for this building. Reference
IBC 1613.3.5 for determination of seismic design category.
c) The calculations show the original forces being reduced by a factor of 1.3. This appears to
be based on an assumed difference between the original design in which rho=1.3 and the
subsequent (current) design in which rho=1.0. However, the original design uses rho=1.0.
BLD17-1714 (Structural Review)
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16425 SE 66th Street, Bellevue, WA 98006 ● beckpllc@msn.com ● PH: 206-313-3739
The reduction is therefore not be applicable. Please clarify where this reduction in forces
comes from. Provide an analysis and/or justification for this reduction.
9) Nowhere in the frame analysis program (ENERCALC) are member forces and stresses
provided. These need to be included in the frame analysis for our review.
10) Reference the footing design analysis provided for the West Frame. The analysis shows the
footing failing in numerous locations. The analysis/design will need to be revised accordingly.
E. Gym & Kitchen Revisions (FB14)
11) We take no exception to the proposed beam and supports.
Please contact me should you have any questions.
Respectfully,
Douglas Beck, PE, SE
Beck & Associates, PLLC