2024 12 17 Packet website

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requirements. A study was conducted to determine the feasibility of adding this 2rd story 
addition. 
The new proposed second story addition is expected to be constructed of structural steel 
main lateral frames and girders, with open-web steel joists, supporting a wide-ribbed steel roof 
deck. This system is chosen as the most lightweight structural option that can span between 
the existing columns below and support the proposed new floor and roof. The new proposed 
second floor would be constructed immediately above the existing roof structure , thus not 
loading the existing roof framing system of the Municipal Building. This f1oor system consists of 
composite structural steel with 3 ¼" lightweight concrete on 2" composite floor decking for a 
total slab depth of 5 ¼". The structural steel beams and girders will span between the new 
columns . This would create a small interstitial space between the proposed new noor and the 
existing roof of approximately 4-ft. This interstitial space allows for the structural member 
depth and the HVAC system, below the floor. 
The proposed new second story construction addition must be designed in accordance with 
the new building code (International Building Code, IBC). With that in mind, the wind and 
seismic lateral force resisting system must meet the new code provisions, that have serious 
requirements for seismic, as this is a Risk Category IV facility . The increased ductility detailing 
requirements are well above the legacy code designs of the existing building. The existing 
building has been assessed utilizing the International Existing Building Code (IEBC), since it is 
referenced in IBC for assessing the gravity and lateral systems to see if a full-building seismic 
retrofit of the existing building is warranted . 
The IEBC has a 5% overstress trigger for reinforcing existing members due to gravity loads. The 
IEBC also has a very specific requirements for the trigger on the seismic reinforcing of an 
existing building . The IEBC has a 10% overstress trigger for reinforcing the lateral force 
resisting members and the system. When the 1 0% overstress trigge r is exceeded, the existing 
facility has to meet both strength and ductility detailing requirements of IEBC and ASCE 41 _ 
Since the original lateral force resistingsvstem was designed under legaQ(codes that have 
signlficanrlvless resistance than IEBC and none of the required ductllitvdetatling the entire 
building would fat! the "as-is" sratus and would require a complete building retrofit Thus, if the 
seismic reinforcing requirement is triggered (overstress in any element >10%), then the original 
building could not practically implement the detailing requirements into an existing building. It 
would require an extensive and cost prohibitive solution to accomplish . 
After modeling the lateral system and adding the proposed new addition to the Municipal 
Building, the existing roof diaphragm and the existing shear walls were above the 10% 
overstress allowable and thus the trigger for a retrofit for the entire facility is required, in our 
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