Does the 2016 US loading standard have any changes compared to 2010?
Major Changes in ASCE 7-16
The ASCE7-16 code has significant changes in earthquake, wind, snow, etc. loading.
– At first glance, about 35% has been added to the previous volume of content.
– A separate chapter for tsunami and its effects has been added to the regulation (Chapter 6).
– The combination of loads is not introduced at once. For example, the combination of design loads using the ultimate strength method is presented as follows:
ASCE7-16:
1. 1.4D
2. 1.2D + 1.6L + 0.5 (Lr or S or R)
3. 1.2D + 1.6(Lr or S or R)+(L or 0.5W)
4. 1.2D + 1.0W + L + 0.5 (Lr or S or R)
5. 0.9D + 1.0W
ASCE7-10:
1. 1.4D
2. 1.2D + 1.6L + 0.5 (Lr or S or R)
3. 1.2D + 1.6(Lr or S or R) + (L or 0.5W)
4. 1.2D + 1.0W + L + 0.5 (Lr or S or R)
5. 1.2D + 1.0E + L + 0.2S
6. 0.9D + 1.0W
7. 0.9D + 1.0E
As can be seen, the 2016 version did not include the earthquake loads in the main loads and listed them separately in Section 2.3.6:
ASCE7-16:
6. 1.2D + Ev + Eh + L + 0.2S
7. 0.9D − Ev + Eh
– The expression form of horizontal and vertical earthquake loads has also been changed and is given separately in the combination of loads. But in general, no change can be seen in terms of coefficients.
– In the allowable stress section, the number of combinations has increased many times. In this section, the combination of loads including earthquake load is given separately.
ASCE7-10:
1. D
2. D + L
3. D + (Lr or S or R)
4. D + 0.75L + 0.75 (Lr or S or R)
5. D + (0.6W or 0.7E)
6a. D + 0.75L + 0.75(0.6W) + 0.75(Lr or S or R)
6b. D + 0.75L + 0.75(0.7E) + 0.75S
7. 0.6D + 0.6W
8. 0.6D + 0.7E
ASCE7-16:
1. D
2. D + L
3. D+ (Lr or S or R)
4. D + 0.75L + 0.75 (Lr or S or R)
5. D+ (0.6W)
6. D + 0.75L + 0.75(0.6W)+ + 0.75(Lr or S or R)
7. 0.6D + 0.6W
8. 1.0D + 0.7Ev + 0.7Eh
9. 1.0D + 0.525Ev + 0.525Eh + 0.75L + 0.75S
10. 0.6D − 0.7Ev + 0.7Eh
– Live load reduction does not change.
– The shape of the spectrum does not differ.
– There are no major changes in the behavior coefficient table.
– Irregular examples do not change in plan and height.
– The relationship for determining the amount of vertical earthquake force does not change and is defined as follows:
Ev = 0.2*Sds*D
– For structures in seismic classification C and above, a new relationship has been given to determine the vertical force of an earthquake:
Ev = 0.3*Sav*D
– Many controls and seismic criteria are the same between the two regulations.
This and other changes will be mentioned in future posts.
(Dr. Alirezaei)
This post is written by AminNajafgholizadeh