HomeMy WebLinkAboutM_Structural Letter_Aeroplastics_230307_v1.pdf833 HOUSER WAREHOUSi_
Seismic/Structural Basis of Design
February 2023; Project No. S212806-01
INTRODUCTION
The purpose of this document is to describe the structural analysis that has been performed on the
833 Houser North Warehouse to date, the findings and recommendations based on this analysis, and
the proposed design basis for the building strengthening. We understand a tenant improvement will be
performed on the building, with a change from warehouse occupancy to manufacturing in less than
50% of the building. Our findings of the structural code requirements are presented below.
BUILDING DESCRIPTION
The building is located at 833 Houser North in Renton, Washington. The building is a one-story,
precast concrete, tilt -up building constructed in the 1960s. The building is on a relatively flat site.
There is an adjacent, smaller, one-story steel framed building to the north with a seismic joint between
the two buildings.
Original construction drawings are not available. A brief walkthrough has been performed to observe
the structure and existing conditions.
VERTICAL -LOAD -RESISTING SYSTEM
The roof consists of plywood over 2x wood subpudins at 24-inches on -center spanning to
4x16 pudins at approximately 8-feet on -center spanning to glulam girders. Wood columns
support the roof framing at the interior and the perimeter is supported by precast concrete
pilasters built into the tilt -up panels.
LATERAL -LOAD -RESISTING SYSTEM
The lateral -force -resisting system of the building consists of perimeter concrete shear walls.
The wood roof framing acts as a diaphragm to transfer lateral loads to the shear walls. The
shear walls in turn transfer the lateral loads to the footings.
PROPOSED RENOVATION
We understand Gary Medino is proposing a tenant improvement to install manufacturing within less
than 50 percent of the building. We understand the original use for the building was manufacturing,
that it was later used as storage, and will now be converted back to manufacturing. Structural work for
the tenant improvement is not anticipated.
STRUCTURAL CODE ANALYSIS AND CRITERIA
The City of Renton has adopted the 2018 International Existing Building Code (IEBC). The code
provisions that need to be considered for this building with the proposed renovations are the
Alterations and Change of Occupancy sections. Additions to the building are not currently proposed.
Summary
The proposed renovations do NOT trigger a mandatory full seismic or gravity upgrade.
Alterations
The proposed renovation, based on the architectural changes, is likely classified as an
Alteration and shall comply with Section 503 of the IEBC. However, per Section 503.4 and
Section 202, it is only a Substantial Structural Alteration if more than 30% of the structure is
altered. Based on the proposed renovation, the Substantial Structural Alteration provisions
will NOT be triggered.
COUGHLINPORTERLUNDEEN
STRUCTURAL CIVIL SEISMIC ENGINEERING
FILE NAME
RS_Structural Seismic Anylasis_230212 v1
833 HOUSER WAREHOUSE
IEBC Section 503.7 requires anchorage of the walls to the roof if the work area exceeds 50
percent of the building area. We understand that the work area is less than 50 percent, thus
wall anchors are NOT required.
Change of Occupancy
The change in occupancy does NOT have additional seismic or gravity upgrade triggers
The proposed change from storage to manufacturing may also involve a change of
occupancy. Per Section 506.4.3 of the IEBC, the building only needs to comply with IBC -
level seismic forces IF the building changes to a higher risk category as defined by Table
1604.5 of the IBC. Per Table 1604.5, both uses are a Risk Category II. Changing from
storage to manufacturing will NOT move the building to a higher risk category, thus avoiding
the additional seismic upgrade triggers. In addition, the building was originally designed
assuming a manufacturing use.
The gravity load requirements for the roof framing are the same for both manufacturing and
storage, thus gravity structural upgrade requirements are NOT triggered.
CONCLUSIONS
Based on the analyses described above, structural renovations are NOT required by the 2018 IBC or
IEBC with Washington State amendments.
COUGHLINPORTERLUNDEEN
STRUCTURAL CIVIL SEISMIC ENGINEERING