Hello. We are designing seismic restraints for a sprinkling system and are using NFPA 13, 1996 as the specified code. The seismic force is generated by the weight of the water filled pipe.
Using ASCE 7-05 (another project specified code) from section 13.3 we calculated Fph = 1.66 Wp. This is due to our rather large earthquake response factors.
We equate Fph from ASCE 7-05 to NFPA's Fp in section 4-14.4.3.5.3. Based on that we are directed through "exceptions" to multiply the longitudinal and lateral loads by an additional factor of 2.4, because our Fp=1.66Wp > 1.2Wp.
This seems that we are artificially adding additional loads to our design. Our result is a lateral and longitudinal load that is 4 times greater (!) than the tributary pipe gravity weight.
Can someone help confirm our approach? Thank you very much in advance.
Using ASCE 7-05 (another project specified code) from section 13.3 we calculated Fph = 1.66 Wp. This is due to our rather large earthquake response factors.
We equate Fph from ASCE 7-05 to NFPA's Fp in section 4-14.4.3.5.3. Based on that we are directed through "exceptions" to multiply the longitudinal and lateral loads by an additional factor of 2.4, because our Fp=1.66Wp > 1.2Wp.
This seems that we are artificially adding additional loads to our design. Our result is a lateral and longitudinal load that is 4 times greater (!) than the tributary pipe gravity weight.
Can someone help confirm our approach? Thank you very much in advance.