Specific features of the static calculation of underground pipelines of gravity wastewater disposal systems

Необходимым условием экологически безопасной и надежной эксплуатации подземных трубопроводов самотечных систем водоотведения является определение требований к прочностным характеристикам элементов строительной конструкции (труб, фасонных частей), которые формируются на основании статического расчета трубопровода. При статическом расчете определяются и анализируются прямые и косвенные нагрузки, действующие на трубопровод, и производится оценка их влияния на конструкцию. Рассматриваются существующие подходы к выполнению статического расчета. На основании результатов исследований российских и зарубежных авторов утверждается, что выбор параметров труб, используемых при строительстве подземных трубопроводов, зависит не только от свойств конструкционных материалов, но прежде всего от свойств грунта, условий укладки и монтажа, а также от действующих нагрузок и степени деформации трубопровода. An essential pre-requisite for environmentally safe and reliable operation of underground pipelines of gravity wastewater disposal systems is specifying the requirements for the structural behavior of building construction elements (pipes, fittings) that are determined on the basis of a static calculation of the pipeline. In the process of the static analysis, direct and indirect loadings acting on the pipeline are determined and analyzed, and their impact on the structure is estimated. Existing approaches to performing a static analysis are considered. Based on the results of the studies carried out by Russian and foreign authors, it has been argued that the choice of the pipe parameters used in the construction of underground pipelines depends not only on the properties of structural materials, but primarily on the soil properties, conditions of laying and installation, as well as on the existing loadings and degree of pipeline deformation.

Evaluation of seismic forces under modified structural schemes in the process of vibrations

The aim of the work - development of one of the possible methods for seismic analysis that considers the inelastic behavior of structures under seismic loads. This requires the development of seismic analysis methods that take into account the change (decrease) in the bearing capacity or the destruction of individual elements until the final loss of the bearing capacity of the structure. Methods. The dependences and algorithms include determining seismic forces using the method of normal forms, which until now is the main one in solving problems of the seismic resistance theory in seismic regions, calculation formulas to calculate seismic forces at each time step are presented in the form of expansions into natural vibration modes, which regard the changes in the design scheme. The calculation is repeated at each time step as a static calculation for the action of seismic forces determined at the previous stage, before the building collapses. Results. The developed dependencies and algorithms allow to consider changes in the design scheme during vibrations at each time step, changes in the dynamic properties of the building and, as a result, the values of seismic forces. The value of the coefficient of inelastic work of structures K 1, which are given in regulatory documents, do not give fully correspond to the actual behavior of the structure under seismic influences. The proposed calculation method allows to determine the estimated values of seismic forces and their distribution taking into account the influence of damage of elements and the appearance of inelastic zones in the design process of fluctuations at each time step and to assess the dynamic behavior of the building.

PIPE-CONCRETE CENTRALLY-LOADED SUB-COLUMN OF A STEEL COLUMN FOUNDATION

A new progressive solution is considered, which consists in improving the design and static calculation of the strength of the elements of the sub-column part of a pipe-concrete foundation, in simplifying the design of a sub-column made of structural concrete of increased and high strength and a thin-walled metal pipe, using it in the form of a permanent formwork as a working element of a composite structure, in reduction of labor intensity and terms of performance of works of the zero cycle. An algorithm is proposed for designing elements of a precast-monolithic reinforced concrete foundation for a column, including a pipe-concrete sub-column, its fl ange connection with a steel column from above and with a foundation slab from below. Thin-walled pipe metal is an economical casing for in-situ concrete.

Assessment of masonry structure “Radnički dom” in Mostar

The paper presents the assessment of the building “Radnički dom” (Workers’ Home) in Mostar, which was built in the Austro-Hungarian period, and represents one of the buildings of cultural and historical significance, located in the area of the historic urban core of the city. The paper explains the steps in assessing the condition of the existing structure, which include the collection of existing documentation, structural inspections, tests and calculations, and the assessment and decision on further action. The paper presents the drafts and gives descriptions of the performed visual inspection and the performed static calculation of the existing structure. At the end of the paper, recommendations are given for the rehabilitation and consolidation of the walls of the building: classical methods (injection and grouting) as well as modern methods (carbon strips). The paper points out the complexity of the procedure for the restoration of cultural and historical heritage buildings, the need for valid expertise of the condition and causes of building degradation, the importance of designing details of new structural elements and their corresponding and adequate connections with the original structure of the object.

GENERAL APPROACH TO THE DESIGN OF COMPLEX BAR AND PLATE SYSTEMS ON AN ARBITRARY ELASTIC FOUNDATION

This paper generalizes the method of static calculation of complex rod and plate systems on an arbitrary elastic foundation under the action of an external load, when modeling the foundation with various models, ranging from the classical Winkler model to a combined model consisting of the Winkler model and the Kogan two-layer model. The relevance and timeliness of the proposed work lies in the fact that the issues of calculating complex structures on an elastic foundation have not yet been fully investigated and there is no general approach to their calculation. The author knows the works of M.I. Gorbunova-Posadova, I.A. Simvulidi, G. Ya. Popova, S.N. Klepikova, S.D. Semenyuk, in which various approaches were used to study the design of simple rod structures, isolated foundation slabs, including mesh slabs, as well as spatial monolithic foundations, as a system of cross belts on an elastic foundation. The proposed technique is based on the Ritz variational method and the mixed method of structural mechanics using Zhemochkin’s influence functions. To determine the coefficients of the canonical equations and free terms of the mixed method of structural mechanics through the Zhemochkin method, the calculation uses the ratios for the deflections of plates or beams with pinching in their center. To simplify the relations of the Zhemochkin method in hinged-connected beams, it is convenient to introduce pinching with unknown displacements at the beginning or end of each beam. The numerical implementation of the general approach was carried out using the Mathematica computer program.

Bending of flexible round plates

In this paper, schemes for constructing solutions to boundary value problems for static calculation of flexible circular plates with the nonlinear theory of Lyava and Volmyr are presented. From the equations of the equilibrium system of the plates, given in curvilinear coordinates, the system of equilibrium equations for flexible round plates is obtained. Substituting the expressions for the efforts and shearing forces and introducing dimensionless quantities, we obtain a system of quasilinear quantities in displacements. To develop an automated system for static calculation of flexible round plates, we use central finite-difference schemes that approximate derivatives with second-order accuracy, we obtain a system of quasilinear algebraic equations. To test the constructed automatic system for static calculation, the difference equations are reduced to vector form. An implicit iterative process combined with the Gaussian elimination method is applied to the solution of the system of equations. When calculating iterative processes, it continues until the above conditions are met. After determining the required functions by the finite difference method, we calculate the calculated values. Using the obtained numerical results, we will construct their graphs.

Some issues of calculation of complex rod and plate systems on an elastic base

This paper summarizes some issues of a new universal method for static calculation of complex rod and plate systems on an arbitrary elastic base under the influence of an external load, when modeling the base with various models, ranging from the classical Winkler model to the combined Winkler-Kogan model. The relevance and timeliness of the proposed work lies in the fact that the issues of calculating complex structures on an elastic base have not yet been fully investigated and there is no general approach to their calculation. The author knows the works of M. I. Gorbunov-Posadov, I. A. Simvulidi, B. N. Zhemochkin, G. Ya. Popov, S. N. Klepikov, S. D. Semenyuk, S. V. Bosakov, in which various approaches have been used to conduct research on the calculation of simple core structures, isolated foundation structures, including mesh slabs, as well as spatial monolithic foundations, as a system of cross belts on an elastic base. The proposed method is based on a mixed method of structural mechanics using the functions of the influence of an elastic medium in the relations of B. N. Zhemochkin. To simplify these relations, when determining the coefficients of canonical equations and free terms of the mixed method in the calculation of isolated and connected plates, the relations for deflections of plates with a normal pinched in the centre of the plate are used. For pivotally connected beams, it is convenient to introduce pinching with unknown displacements at the beginning or end of each beam, for frame rods-in their nodal connections. The numerical implementation of the general approach is performed using the Mathematica computer program.

Application of mobile devices for the rapid assessment of masonry arch bridges – worked example and benchmarking

<p>Reassessment of masonry arches necessitates feasible methods for analysing the static behaviour of the persisting structure and an applicable way how to calculate the remaining load bearing capacity. Especially when a quick assessment of a structure is necessary, easily measurable characteristics, such as geometric properties have to be used. In this paper, the existing Application BRASSCO-NG is extended for masonry arch bridges by implementing the methodology described in paper [16] of this conference proceedings. Embedded into a worked example, the application of the tool is explained in detail from the first reconnaissance to the interpretation of the results. A subsequent benchmark evaluation to the static calculation and the empirical MEXE methodology compares the outcome to the techniques currently used in military and civil engineering. Even though the tool is mainly aimed for military application, the basic structure can easily be adopted for civil use, e.g. the rapid assessment of a structure after a natural disaster.</p>

Optimization design of elastomeric locks

This paper discusses the development of small boats made of polymeric composites in combination with metal skeleton based on detachable elastic connections. Lock material was polyethylene with hyperelastic properties of an elastomer. Static calculation is performed as per the finite-element method in plane formulation taking into account contact, geometric and physical non-linearity, as well as implementing a step-wise procedure. Design calculation is performed as per the research method approximating the sub-task (quadratic programming). The paper presents calculations for the process of inserting/extracting a rigid bar with round free flange to/from the lock, with determination of maximum responses, strains and stresses of the insert. Variation of geometric parameters yielded a design variant with minimum load on the insert and the same strength properties as the initial design. The study also yielded the analytical design methodology for elastic detachable connections that combines the solutions to non-linear contact problem and the optimization problem.