Design of precast reinforced concrete structures of frame buildings: a new set of rules

Promyshlennoe i Grazhdanskoe Stroitel stvo ◽

10.33622/0869-7019.2019.04.04-09 ◽

2019 ◽

pp. 4-9 ◽

Cited By ~ 1

Keyword(s):

Reinforced Concrete ◽

Concrete Structures ◽

Reinforced Concrete Structures ◽

Building Frames ◽

Fine Grained ◽

Rigid Frame ◽

Floor Slabs ◽

Frame Buildings ◽

Spatial System ◽

Precast Elements

Currently, prefabricated reinforced concrete structures are widely used for the construction of buildings of various functional purposes. In this regard, has been developed SP 356.1325800.2017 "Frame Reinforced Concrete Prefabricated Structures of Multi-Storey Buildings. Design Rules", which establishes requirements for the calculation and design of precast reinforced concrete structures of frame buildings of heavy, fine-grained and lightweight structural concrete for buildings with a height of not more than 75 m. The structure of the set of rules consists of eight sections and one annex. The document reviewed covers the design of multi-story framed beam structural systems, the elements of which are connected in a spatial system with rigid (partially compliant) or hinged joints and concreting of the joints between the surfaces of the abutting precast elements. The classification of structural schemes of building frames, which according to the method of accommodation of horizontal loads are divided into bracing, rigid frame bracing and framework, is presented. The list of structural elements, such as foundations, columns, crossbars, ribbed and hollow floor slabs and coatings, stiffness elements and external enclosing structures is given; detailed instructions for their design are provided. The scope of the developed set of rules includes all natural and climatic zones of the Russian Federation, except seismic areas with 7 or more points, as well as permafrost zones.

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Effective reinforced concrete structures of monolithic frame buildings and structures

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/913/3/032049 ◽

2020 ◽

Vol 913 ◽

pp. 032049

Author(s):

D R Mailyan ◽

Valerio Arreola Lucia Del Socorro

Keyword(s):

Reinforced Concrete ◽

Concrete Structures ◽

Reinforced Concrete Structures ◽

Frame Buildings

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Design of reinforced concrete slabs subject to the construction joints

Vestnik MGSU ◽

10.22227/1997-0935.2019.9.1106-1120 ◽

2019 ◽

pp. 1106-1120

Author(s):

Andrei V. Deineko ◽

Valentina A. Kurochkina ◽

Irina Yu. Yakovleva ◽

Aleksandr N. Starostin

Keyword(s):

Reinforced Concrete ◽

Concrete Structure ◽

Concrete Structures ◽

Reinforced Concrete Structures ◽

Reinforced Concrete Structure ◽

Construction Joint ◽

Floor Slabs ◽

Deformation State ◽

Stress Deformation ◽

Construction Joints

Introduction. When erecting monolithic reinforced concrete floor slabs, a necessity of construction joints arises. The construction joints are the areas of structural weakening. The construction practice shows that the compliance with the correct technology of the construction joint arrangement is not a sufficient condition to ensure the strength balance of reinforced concrete floor slabs. As a result, the stress-deformation state calculated on the assumption of the concrete slab solidity deviates from the actual state. The relevance of the task is determined by the fact that the conformity of design and actual characteristics of the in-situ reinforced concrete structures as a whole depends on the correct calculations of construction joints. Materials and methods. The problem of implementing the construction joints in the monolithic floor slabs was considered by way of example of a residential building under construction. In the course of construction, pre-construction land surveys were carried out at the areas of the construction joint arrangement. Calculations of reinforced concrete structures using finite element method (FEM) were also performed. Results. As a result of the study, the actual deflections of the floor slabs were measured at the areas of the construction joints and FEM calculations were made on the same floor slabs, both those erected at once and those erected in stages subject to the construction joints. The difference between the calculated and actual deflections is conditioned upon the inaccurate conformity between the mathematical model and the real reinforced concrete structure, its erection and maintenance conditions. It should be noted that the deflection of horizontal reinforced concrete structures is only one of the stress-deformation state parameters that can be measured better than the others. It is shown that if the deflection of a real reinforced concrete structure does not correspond with the design estimation, the other stress-deformation state parameters will differ from the design estimation as well. Conclusions. The influence of joints can be taken into account in the scope of FEM computer-aided calculations with the explicit reproduction of the structure erection by pouring concrete, using engineering approach to the consideration of nonlinearity on the basis of the introducing reduction coefficients to the reinforced concrete effective modulus of elasticity. Solid composition modeling of reinforced concrete provides the best possibilities on taking all sorts of nonlinearity manifestations into consideration.

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Improvement Of Curvilinear Diagrams Of Concrete Deformation

Promyshlennoe i Grazhdanskoe Stroitel stvo ◽

10.33622/0869-7019.2019.08.99-104 ◽

2019 ◽

pp. 99-104

Keyword(s):

Reinforced Concrete ◽

Peak Load ◽

Experimental Studies ◽

Concrete Structures ◽

Deformation Model ◽

Reinforced Concrete Structures ◽

Significant Difference ◽

Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

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