Gforce1
Structural
- Aug 22, 2023
- 14
Hi,
I am looking for a little help with traffic loading. It's very a UK specific question.
Although not a bridge engineer (I work in Energy) I have to assess a reinforced concrete structure against traffic loading to the CS454 code. I have looked at the following cases:
- Load model 1, CS454, all individual vehicles to appendix B, live load factor = 1.5, wheel impact factor = 1.62
- Load model 2, CS454, HA udl + knife edge loading, live load factor = 1.5
- SV80 load model, CS458, wheel impact factor = 1.0 (speed less than 10mph), live load factor = 1.1
The issue is that because the structure is not capable of resisting SV80 loading I need to look at individual STGO vehicles (specifically mobile cranes). In the case of load model 1 there was a client suggestion to lower the impact factor from 1.62 to 1.2 to reflect low traffic speed (<10mph). When applying crane wheel loads should I. Therefore any assessment of mobile cranes needs to do something similar. The options I have considered for crane wheel loading are:
- Use a live load factor of 1.5 and a impact factor of 1.2?
- Use a live load factor of 1.1 and a impact factor of 1.0? This seems to be what CS458 suggests?
If I apply the second methodology, the factored wheel load (15 tonnes * 1.1 = 16.5 tonnes) is less than that for normal traffic (11.5 * 1.5 = 17.2 tonnes), even without considering the impact factor! This does not seem to be correct.
I have many years of experience dealing with seismic/blast/impact loading, but I am not a bridge engineer. Unfortunately as this is not normally something that we deal with in our office I am struggling to find help.
I am looking for a little help with traffic loading. It's very a UK specific question.
Although not a bridge engineer (I work in Energy) I have to assess a reinforced concrete structure against traffic loading to the CS454 code. I have looked at the following cases:
- Load model 1, CS454, all individual vehicles to appendix B, live load factor = 1.5, wheel impact factor = 1.62
- Load model 2, CS454, HA udl + knife edge loading, live load factor = 1.5
- SV80 load model, CS458, wheel impact factor = 1.0 (speed less than 10mph), live load factor = 1.1
The issue is that because the structure is not capable of resisting SV80 loading I need to look at individual STGO vehicles (specifically mobile cranes). In the case of load model 1 there was a client suggestion to lower the impact factor from 1.62 to 1.2 to reflect low traffic speed (<10mph). When applying crane wheel loads should I. Therefore any assessment of mobile cranes needs to do something similar. The options I have considered for crane wheel loading are:
- Use a live load factor of 1.5 and a impact factor of 1.2?
- Use a live load factor of 1.1 and a impact factor of 1.0? This seems to be what CS458 suggests?
If I apply the second methodology, the factored wheel load (15 tonnes * 1.1 = 16.5 tonnes) is less than that for normal traffic (11.5 * 1.5 = 17.2 tonnes), even without considering the impact factor! This does not seem to be correct.
I have many years of experience dealing with seismic/blast/impact loading, but I am not a bridge engineer. Unfortunately as this is not normally something that we deal with in our office I am struggling to find help.
