|At this page I place reports, articles, preprints on structural analysis. Your questions and remarks coming through e-mail will take place here as well.|
In computational analysis of buildings of large number of storeys one
has to take into account multiple erection stages and sequential
appliance of loading. In this paper I suggest the “quick” method
of accounting of multiple erection stages (without composing the
mounting tables e. c.):
In strength analysis of reinforced monolithic structures the shear
stress collateral to reinforcing steel is not accounted. In
presented paper the stress state of armored
concrete diaphragms is investigated and the safety criteria is suggested for the
marginal state of first grope:
In the next paper I suggest the technique of stochastic prognosis
for deflections of monolithic floor up to an operation period, by
means of deflections’ measurements at the erection period. The
technique is based on development of regression model for
evaluating the concrete strength characteristics and slab’s
The accuracy of stress state analysis of monolithic slab by means
of elastic model is dependent on the step of finite element mesh;
in this connection, excessive thickening of FE-mesh would make the result inadequate.
The problem of specifying the FE size is under investigation in the
In the next paper I suggest the method of numerical modeling of a pile foundation as a system of elastic links on the square nodal mesh, covering the basement surface. In new method each node is linked to the earth by elastic support — the one modeling the compression strain of a soil — and to an every adjacent node by vertical elastic link — the one modeling the shear strain of a soil. Stiffness characteristics of elastic links have been derived for securing model adequacy. Obtained by different methods comparative analysis of computational results has been presented:
In the next paper I suggest the method of pile’s bearing capability evaluation
for a pile field in hydrocompactive soil. The method takes into account soil-pile
interaction due to watering. The equilibrium equation of watered hydrocompactive
strata loaded with pile foundation has been obtained and, by its solving, the safe
bearing load of a pile is evaluated. It is established that this bearing load
is higher then one being calculated by actual standards, the latter is caused by
relief of hydrocompactive strata "hung" on the piles. The paper consists of two
parts published as follows:
The results of computational analysis for a building with monolithic
skeleton are got up in two reports: on the base analysis and
skeleton analysis respectively. The initial stage of works is the
elaboration of skeleton’s FEM, to specify input data for base
analysis. The technique of base analysis by means of FE-modeling
under LIRA is described here:
Next report is realized in the same concept as the previous one, but more breafly
(the shortening by means of automation the portion of calculations with program
For a monolithic skeleton with panel-type walling there is peculiarity
of loading to the slab caused by the panels. For instance, these
loadings are applied at no whole line of contact. Read the details
Numeric analysis of strength of retaining wall piled of stones or
concrete blocks is made by hand yet calculations are laborious.
In the next report it is considered the wall with uncemented
STRENGH ANALYSIS OF RETAINING WALL FOR A PIT UNDER THE OFFICE BUILDING (Technical Report), 2008. (in Russian.) File XPS, 1.56 MB. (install XPS-viewer, for instance, MS Office)
Next technique includes the strength analysis of supporting belts
for walling brickwork:
Next report includes the solution of the problem of analysis of sheet piling
as the geotechnical barrier between the buildings. It is under consideration
neither stability or strength of piling but its functioning for abatement of
deformation of existing building, situated next to the ground of new construction:
THE ANALYSIS OF SHEET PILING, FUNCTIONING AS GEOTECHNICAL BARRIER BETWEEN OFFICE BUILDINGS (Technical Report), 2011. (in Russian.) File PDF, 204K.
On my opinion, the worthiness of this paper is either of setting forth the manual calculation technique and of the references to guideline instructions on the question. This report is to be studied together with the addition at the end of document, which presents the response to the note of expertise summary.
Next documents give concept of constructions by my own devise of retaining
walls, consisting of basic perforated blocks (fundamental hollow blocks),
The typography for results of monolithic skeleton analysis must correspond to GOST 2.105-95, and report content is to SP 52-103-2007. It is presented here the part of report of strength analysis for two-sectional 17-storey house like a pattern of typography (all in Russian). In particular, it is presented the technique of punching analysis, elaborated in accordance with “Instruction on Projecting of Concrete Structures of Solid Concrete” (Supplement to SP 52-101-2003, TsNIIpromzdanij, Moscow, 2005)
Title, Contents, Input Data for Analysis File PDF, 593K.
Special Analysis File PDF, 312K.
The Punching Analysis File PDF, 131K.
Mat Foundation Reinforcement File PDF, 98K.
. . . . . . . . .
Columns Reinforcement File PDF, 127K.
. . . . . . . . .
Stiffening Diaphragms Reinforcement File PDF, 215K.
Conclusion File PDF, 44K.
- This sample had been placed here on february of 2010. Lately there stated additional
demands to the report contents. Now one has to include the analysis of dynamic comfort
for the building, and the item of stiffnesses should be supplied with pictures of the
ones (the stiffnesses must be coloured).
Received on 12.03.2010:
How do you do, Al. Iv.? On your wish and convenience, would you be so kind to consider my problem? In the one I’ve applied ARB to joint the columns, diaphragms, slabs… I’m interested of your opinion about this approach. Would be very thankful for your response.
With best respect, Nicolas.
Sent on 14.06.2010:
Received on 3.04.2011:
How do you do, Al. Iv.? In my work I come across the analysis of steel spatial frames. There is urgent problem about specification of element CS for bars modeling. On the plots it is depicted some instances of CS specifications for the braces. This problem arises in attachment of sections of supports of power transmission line. How to choose better the design model?
With best respect, Irina.
Sent on 25.04.2011:
Specification of ECS is recommended that one, which you consider most handy, but if one doesn’t make the mistakes on frame structure analysis. The mistakes happen if ECS are specified with no relation to main inertia axes. For the PTL tower, which erected of equal-flange angle bars, both decisions on plot 1 and 2 are erroneous: all the axes Z belong to flanges, whereas must belong to the symmetry plain of angle bar. Result is: when verifying the slenderness of the bar, you get real slenderness by 1.5 times greater then modeling one (check this).
In this relation there is interesting question about modeling a beam of asymmetrical cross-section: by default, bearing reactions and line of action for any load applied to virtual (modeled) beam do cross stiffness line but not certainly center line of a beam. For example, stiffness line of the beam on the picture is at the joint of flanges, and just at this line the beam is considered fixed and loaded. If the vertical force plain crossed the center line, the beam would get torsion and being deformed not only downward but also sideward.
Received on 4.04.2013:
Dear Al. Iv., an urgent asking for help! The element coordinate axes of the walls and columns of 10-storey monolithic building is being turned by 45 degrees to global axes. Has it influence upon the analysis results? Are there any mistakes in the program LIRA_2012? - There are large moments (50 ton*m) in the numerical results.
With best respect, Tamara.
Sent on 8.04.2013:
If you mean the floors, then the moment at the cross section of a column > 20 ton*m is yet suspicious. The calculation of internal forces in the bars is correct in all versions of LIRA. The rotation of element axes is not valuable for the order of magnitude of the moments.
My best wishes, A. R.
Sent on 29.04.2013:
I suppose that model's bug you have found out yourself. But there are any considerations which might be interesting to you:
1. It is not easy to discover doubled loads in Lira 9.x. If by any mistake you have applied the load to an element a few times, then only way to discover this is to display the load replicas at the window "Information about node or element".
2. If erroneously you have introduced the surplus link to the ground but on the one node, then internal forces in vicinity to the node is essentially distorted and may increase significantly.
With best regards, A. R.
Received on 6.05.2014:
How do you do, Al. Iv.?
When applying software “Lira-SAPR” for analysis of multi-storey monolithic skeleton, we have got the question about the joint flexibility at girderless non-capital monolithic floors due to i.5.14 SP 52-103-2007 from expertise.
. . . . . . . .
5.14. In column constructive systems the joints of multi-storey spatial frames are considered as rigid in presence of capitals in slabs or haunches in girders. The joints of columns with smooth slab or girders are conventionally rigid. … The joint flexibility is taken into account by factors, reducing bending stiffness of elements.
. . . . . . . .
In your reports uploaded in site we didn’t see any mention on the issue. Is the flexibility has been taken into account in software “Lira”, and by what factors it is varied? Where could we see that?
With best respect, Natalia and Constantin
Sent on 6.05.2014:
The flexibility of joint can be considered as the presence of elastic hinges, or flexible joints at the ends of columns. Such joints are taken into account in accordance with i.6.2.18 of SP 52-101-2003. The factors decreasing the critical force of buckling make design length of columns greater and are specified in “Lira” at the stage of reinforcement. I recommend to take the design length of columns inside the slab’s outline l_0 = 0.8*l (shiftless flexible supports at the top and bottom), for columns at the edge of floor to take hinged support: l_0 = l.
With best regards, A. R.
Received on 7.05.2014:
Thanks, Al. Iv.
We took the design length of columns l_0 = l beforehand.
To do nonlinear analysis of a floor — is it consideration of the joint flexibility? …
Good wishes, N.Sch.
Sent on 8.05.2014:
Don’t do nonlinear analysis, physical nonlinearity in “Lira” is not supposed for that.
I would repeat my last advice: the decrease of stiffness of the support cross-sections of column and elastic work of slab in site of support generate elastic hinges (or flexible joints). In case of ideal rigid joint we have: l_0 = 0.5*l (see any textbook on strength of materials); for real monolithic column: l_0 = 0.8*l (see i. 6.2.18 of SP 52-101-2003); in case of hinged supports, when joints do not oppose to bending, l_0 = l. Do you notice the design length increase? In your calculations you have taken into account the flexibility of joint by wide margin!
Good luck! A.R.
Received on 4.04.2015:
Dear Al. Iv., how do you do?
I’m studying materials of your site and got interested in question of sheetpiling settlement calculation. Now I solve analogous problem, the questions have arisen:
1. In my problem the bed plate of new building is situated above the foundation of existing building,
2. You estimate only the settlement of soil strata below the piles down to the depth of compressed thickness due to a new building. But do the piles not settle with a new building (in analogy with the forces of negative friction in case of soil slumping)?
3. Please, suggest the method of sheetpiling calculation with determination of the step, cross-section, and reinforcement of piles. Is there in my case analogy with pile calculation under horizontal force exertion; have I to consider vertical forces?
Sent on 8.04.2015:
There are two functions of sheet piling: retained wall and geotechnical barrier. The independent analysis is necessary for each of these functions. In my case the barrier function of sheet piling is under consideration. Let us limit ourselves in that.
Received on 9.04.2015:
Good afternoon, dear Al. Iv.! Thank you very much for detailed answer!