"musamusa":rghpgarq" said:
In RADIUM FOUNDATION ANALYSIS 1-do the soil safety stress control of the foundations according to the average stress option 2-make a negative ground stress control in the foundations 3-soil in the foundations 1- What is the logic of calculating according to the average stress, why do we calculate according to the average stress when the normal stress is stopped, and if we do not use this option, it is difficult to save the foundations. Whatever we do. Is this because the previous versions solve the basics very safely (versions before 6) 2-What is the purpose of doing this check? We are a 3-earthquake country, as it is known, a large area of our country is a 1st and 2nd degree earthquake zone.. In this case, why is this an option? that is, what is the rationale for not using earthquake loadings in soil safety stress control? thanks
Hello,
Your 1st question: Soil data are obtained by experimental results, especially in foundation calculations, the value of the 1st degree important soil bearing coefficient can vary greatly depending on the soil type. For example, while the bearing coefficient of a soil considered to be in the "
clay, semi-hard" class is in the range of
Ko=1000 ~ 1500 , it is in the "
clay, hard" class. The bearing coefficient of the accepted soil is in the range of
K0=1500 ~ 3000 . We, on the other hand, have to accept the ground bearing coefficient
(1) as a single value in projects. For example, most of us would accept the average
Ko= 2000 for
"clay, hard soil class". The larger the base area in the foundation system, the greater the variability of this value.
Horizontal coefficients according to soil class: Clay, plastic Ko=500 ~ 1000 Clay, semi-hard Ko=1000 ~ 1500 Clay, hard Ko=1500 ~ 3000 Filled soil Ko=1000 ~ 2000 Sand, loose Ko= 1000 ~ 2000 Sand, medium compact Ko=2000 ~ 5000 Sand, firm Ko=5000 ~ 10000 Sand-gravel, firm Ko=10000 ~ 15000 Solid schist Ko> 50000 Rock Ko>200000 The second point is that the soil will give under structural loads and the shape of the reaction it is not very obvious. The ground may show different behaviors according to the loads coming from the structure and again according to the ground type. Sadık Köseoğlu, in his Fundamentals book(
2), divided the deformations that may occur up to the breaking point of the ground into three. Elastic deformation, plastic deformation and compressive deformation. In elastic deformation, the ground is restored when the load is removed. In plastic deformation, it shows negligible deformation when the load is removed. Compressive deformation, on the other hand, is the deformation that occurs when water and air come out of the ground, reducing the void volume and the grains coming closer to each other. More detailed information can be viewed in the relevant book. Now we have to confirm whether the soil stress released as a result of the calculation is less than the maximum soil stress. The deformations that appear at every point of the ground at the base of the building will differ according to the effects of the building. Especially at the bottom of the wall and long columns, due to the sudden increase in moment, much larger deformations may occur in some regions compared to other regions, and due to these deformations, the soil stresses at those points will be higher than the other parts of the foundation. How accurate would it be to retrofit the entire foundation system according to the large ground stress that will arise at these points? At this point, the engineer should be able to find a suitable way out by observing the predicted behavior of the ground. Average stress should be considered as one of the options given to us in this sense.
Your 2nd question: The answer to this is again in the 1st answer. Under the structural loads, we have to observe whether the vertical effects lift the foundation, especially in combinations where the earthquake loads are reversed. Although the program places negative springs in the foundation system, the engineer must decide whether to allow such a behavior of the foundation. While the structure collapses at one point, it can rise at another point. While designing the foundation, we enable the program to warn us with this option. We decide whether to make changes to the build system.
Your third question: Take this as an opportunity. There is an earthquake in our country. We have to design all our structures according to earthquake conditions. Apart from this, we have to give earthquake-free diathesis as an opportunity. For example, you can do a retrofitting project and earthquake effects may not have been basically taken into account at the time. You may also want to solve it and look at the state of the system. Similarly, the program is also in use abroad. For example, in Libya, the value of A0 is taken as 0.02 and the engineer does not use this option. Good work... (1)- The method to spread the ground bearing coefficient on the ground has been added to the program in version 6.0051. (Winkler) (2)- Sadık Köseoğlu Temelller sy:21
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