Fixed-roof live load problem

Theoretically, it should be 1 KN per square meter, which is approximately 100 Kg per square meter. In practical operations, it is generally required that no more than 3 people be present at the same location at any time, or no more than 5 people on the top of the tank (for vaulted tanks).

The last edit to this post was made by fzujunru on 2019-3-1 at 10:07. It’s hard to say for sure, but one can refer to the provisions in GB 50009-2012, the Code for Loads on Building Structures, regarding the uniform live loads on floors of civil buildings. PS: After checking GB 50009 more carefully, it can be seen that the determination of such live loads is outlined in Appendix C of the standard, which details the methods for determining the equivalent uniform loads on floors

I just want to know how a concentrated load is converted into a uniformly distributed load. For example, what is the equivalent live load on the top of the tank if there’s a 50 Kg person on it?

Well, thank you. A few days ago I went to see a tank with a volume of 3,000 cubic meters; 5 or 6 people went up to the top of that tank. So I’m wondering how many people can actually go up on such an arch-shaped tank

This load refers to the load per 0.01 square meter at the thickest part of the tank roof, which is 12.7 mm thick; if this thickness exceeds 12.7 mm, the load also increases. For example, if we use an 8 mm thick plate for the tank roof but the thickest part reaches 16 mm, then the load should be 1.3 KPA

Is it calculated this way too? Generally, the tank roof isn’t 6 inches thick; larger tanks have reinforcement plates

Is this calculation based on something other than mere speculation? These are the rules of this system, or rather the engineering experience, which is the result of decades of accumulation by those who design and use APIs. The 12.7 mentioned here corresponds to approximately 13 mm in the API standards; it refers to the maximum thickness of the tank top before corrosion occurs. Using this value – with the note that it represents the self-weight without any local instability, failure, or deformation at areas such as joints or where the central plate of the roof meets the sectoral plates – as the minimum value for dynamic loads is generally sufficient to ensure the stability of the tank roof. Taking material and processing tolerances into account, this 13 mm is roughly equivalent to the minimum thickness of 5 mm required for the tank top plate. If the top thickness of your tank is 6 mm and Q235B material is used with a Class N deviation of +0.75, the maximum thickness resulting will be around 13.5–14 mm; the value for 1000 PA is similar as well. However, when the wall thickness is 8 mm, it becomes necessary to increase the dynamic load to 1400. These are all minimum requirements; in reality, designers should refine this value through the equipment’s engineering design. However, no problems have occurred thus far, so everyone has continued to use the existing values. February 2nd is approaching, and many people are getting their hair cut for good luck. In fact, this festival originated during the transition between the Ming and Qing dynasties; by today, there are various theories regarding its origins, just as there are 1000 reasons for it. So what I say isn’t necessarily the true teachings of XX. :P

Well, it’s explained in great detail. I’ve seen that before as well; there are people who specialize in explaining the design of large tanks. Our calculation documents follow GB 50341 standards, and indeed the data provided in those standards isn’t very clear. I haven’t come across API standards. Anyway, national standards are all copied from foreign ones. I would like to ask how to deal with concentrated loads on the tank top? Break it down into uniformly distributed loads? How to distribute it evenly? Just divide by the circular area of the cylinder? Previously, there was a large tank equipped with a valve weighing over 1 ton, and at that time the reinforcement plates were strengthened. When conducting the calculations, it wasn’t clear what value to use for the dynamic load. I have always understood that the dynamic load refers to people; so, what does this 1 KPa correspond to in terms of the number of people? Can’t it be converted? What you mean is that the greater the self-weight of the tank top (its thickness), the higher the live load that needs to be considered. I still think the self-weight of the tank top constitutes a fixed load; in 50341, the tank top is accounted for as having both fixed and live loads.

It means that the greater the self-weight of the tank roof (thickness), the larger the live load that needs to be taken into account. As you mentioned regarding the valve assembly on the tank top, simply increasing the number of reinforcement plates on the tank top panel means that the bearing capacity is consumed by the weight of those plates, which is not good. Refinement can be drawn from Appendix B of 50341. Many valve assemblies are proposed only in the later stages of the large tank design phase, making it difficult to incorporate them. It is recommended to raise the valve bank area by installing a small platform on the top of the tank, which provides better load distribution. There’s no need to rush; just thicken the roof slab. By distributing several tons across several points, the local stress is not high. A little over one ton is equivalent to a small car; it fits on top of the tank, no problem.