The author studies pilot research works into combined action of concrete and metal profiles in reinforced concrete constructions with rigid armoring carried out by scholars from both near and far foreign countries. The main methods of providing co-action of the two materials in the compression elements are outlined through the example of columns and flexural elements through the example of a T-beam. The advantages and disadvantages of the proposed methods are analysed

Koltunov, A.

Trubach, Y.

Digital Library of Polotsk State University (Репозиторий Полоцкого государственного университета)

MATERIALS OF VIII JUNIOR RESEARCHERS’ CONFERENCE                                                    2016 Architecture and Civil Engineering  651. The conducted experimental and theoretical studies have shown positive influence of cross-section pressing on bonding strength of prestressed high-strength wire. 2. The studied theoretical bases do not reflect the valid distribution law of tangent stress for high-strength wire.  REFERENCES  1. Лазовский, А.Д. Платформенный стык с местным обжатием зоны анкеровки арматуры плит безопалубочного формования / А.Д. Лазовский // Проблемы соврем. железобетона : сб. науч. тр. – Вып. 6. – Минск, 2014. – С. 176–183. 2. Холмянский, М.М. Контакт арматуры с бетоном / М.М. Холмянский. – М. : Стройиздат, 1981. – 184 с. 3. Shima, H. Micro and Macro Models for Bond in Reinforced concrete / H. Shima, L.-L. Chou, H. Okamura // Journal of the Faculty of Engineering : University of Tokyo. – 1987. – Vol. XXXIX. – No. 2. – Pp. 133–194. 4. Математическое моделирование процесса разрушения сцепления арматуры с бетоном. Часть 1. Модели с уче-том несплошности соединения. / А.В. Бенин [и др.] // Инженерно-стр. журн. – 2013. – № 5. – С. 86–99. 5. CEB-FIP. Model Code for Concrete Structures 2010. International Federation for Structural Concrete (FIB), Lausanne, Switzerland, 2012. 6. Лазовский, Д.Н. Влияние поперечного обжатия на прочность анкеровки арматуры / Д.Н. Лазовский, К.К. Голу-бев, Г.Н. Серяков // Бетон и железобетон. – 1998. – № 1. – С. 15–17.   UDC 624.016  METHODS OF PROVIDING COMBINED ACTION OF CONCRETE AND METAL ROLLED STOCK IN REINFORCED CONCRETE CONSTRUCTIONS WITH RIGID ARMORING  YURY TRUBACH, ALEXANDR KOLTUNOV  Polotsk State University, Belarus  The author studies pilot research works into combined action of concrete and metal profiles in reinforced concrete constructions with rigid armoring carried out by scholars from both near and far foreign countries. The main methods of providing co-action of the two materials in the compression elements are outlined through the example of columns and flexural elements through the example of a T-beam. The advantages and disadvan-tages of the proposed methods are analysed.  We understand reinforced concrete with rigid armoring as structures designed under the assumption of combined action of a metal profile and concrete. The combined action of a rolled metal profile and concrete must be ensured in all types of structures, re-gardless of its operating conditions (bending, compression, shear). The main compression elements are columns. Rigid angle-shaped reinforcement is placed at the corners of normal cross-section, U-sections are arranged in inversed manner in the section of the column with their webs to the face of the column and I-beams are installed in the cross-section of the column so that the flange of the beam is located in the tensile zone of the cross section (eccentric compression) and parallel to the column face. Depending on the operating conditions it’s necessary to provide a protective layer of concrete when you place metal profile in the cross-section of a column. When there is no combined work of a metal rolled stock and con-crete, the main problem is early peeling of a protectiv  layer observed in columns with longitudinal rigid bars without profile bordering in the column body (Fig.1 а). With that in mind to provide combined action Professor Emperger and Professor Zaliger from Higher Technical College of Vienna advise to use spiral hoopings and ties of metal flexible reinforcement 5-8 mm in diameter. Using spiral hooping increases the ability of the concrete to deform under compression without breaking and, hence, makes it possible to fully use refined steel up to the yield point at its combined action with concrete[1]. The feature of using spiral winding is that in the columns of square section only the concrete within wind-ing is taken into consideration (Fig. 1 b). With that in mind, it is more efficient to use ties with additional longi-tudinal bars in the corners of the column that willallow considering all the section of the column, providing an additional protective layer of metal rolled profile and thereby increasing the rigidity of the element (Fig.1 c). By the time of the destruction of column concrete of compression because of its significant plastic defor-mations, its rigid reinforcement reaches its yield point too. Thus, the basis for the calculation of axially loaded elements can be the sum of metal and concrete forces, which was first proposed by Prof. Emperger. Therefore MATERIALS OF VIII JUNIOR RESEARCHERS’ CONFERENCE                                                    2016 Architecture and Civil Engineering  66the theoretical breaking load, calculated by formula (1) was close to experimental values, straying outside them in average by 2% [1].                                                  sysccp ARAARN ⋅+−⋅= )(                                                          (1) where Rc  - design compressive resistance of concrete; Ry  - design compressive resistance of steel; Ac  -  cross-section area of a column; Ay  - cross-section area of a metal rolled stock.  a) b) c)  Fig. 1. Cross-section of columns tested by Professor Emperger  Rigid reinforcement is also used in columns with eccentric compression. The studies of such columns have also been carried out in the post-Soviet area. Based on the results obtained by the Central Research Institute of Building Materials Industry, eccentrically compressed columns with rigid reinforcement tend to show similar results as axially loaded columns. In the group of columns without ties the destruction was a sudden peeling of an unreinforced layer of concrete in the compressed zone along the plane of the flanges and webs leading to loss of stability and suitability for further use of the structure. At the same time in the columns with tie reinforcement there was a more peaceful and gradual destruction of the compressed zone under higher loads. In this case on-crete didn’t peel off from the rigid reinforcement, and being tied was gradually crumbling, allowing the full use of the strength characteristics of metal and concrete. Let’s consider the behavior of rigid reinforcement in bending using the findings of the tests of Central Scientific Research Institute of Construction. All the tested beams were single span, had a T-section and the same shuttering sizes (Fig. 2) [1].  50201030202,5№1250201030202,5№1850201030202,5№243003253025 25   Fig. 2. Beams with rigid reinforcement tested by Central Scientific Research Institute of Construction  In I-shaped reinforced beams No.12 and No.14 in the absence of ties and anchoring ends of the rigid pro-files the destruction was characterized by the shear fracture of concrete. At loads close to the destruction, there were diagonal cracks in supporting parts. These cracks were quickly spreading and developing into a longitudi-nal crack separating the web from the slab. The development of these cracks was accompanied with debonding of I-beams with concrete and pulling them out of the separated support sections. It should be noted that by the time of shear failures there had already been well developed vertical cracks (Fig. 3). MATERIALS OF VIII JUNIOR RESEARCHERS’ CONFERENCE                                                    2016 Architecture and Civil Engineering  67  Fig. 3. The nature of the beam destruction with I-shaped reinforcement No. 12 without anchoring  Beams with I-shaped reinforcement and ends anchoring also had shear failure but at higher loads. The failure was characterized by the development of a horizontal crack that separated the bottom part of the web from the beam slab. By the time of the failure the concrete under the anchoring U-profile had crumbled, and the anchor hit into a support beam part. Anchoring of metal rolled profiles (rigid reinforcement) in the body of the sample was carried out by welding U-profiles to theends, which is represented in Figure 4. At the same ti e anchoring in the samples without welding at the ends of U-profiles was performed by widening the concrete cross-section of the support parts of the beam - haunches[1].  32524№18 №18 №12Сварной шов 3 мм  Fig. 4. Anchoring the ends of rigid armoring of test beams  Beams with ties were destroying at higher loads, wherein there were no longitudinal cracks separating the web from the slab, and diagonal cracks in supports weren’t developing. The failure was characterized by vertical cracks opening in flight and the destruction of compressed slabs. Pulling the I-beams from the supporting part was not observed, indicating that ends anchoring doesn’t affect the reinforcement of test samples with ties around the metal rolled profile, i.e. combined action of reinforcement and concrete was fully ensured that con-tributed to the full use of the strengths of both materials of the reinforced concrete structure[1].  By the moment of destruction the beams, that had neither anchoring of the ends of I-beams nor the mesh in the slabs, had lost bend stress and the beam had been split along its axis, and the beams with I-beams anchor-ing and a slab, and fabric-reinforced, the failure was also characterized by web shear on the verge of connecting with a slab, but we didn’t observe the segregation of beams along the axis. The value of fracture loads in the presence of anchoring was much higher and by the tim  of destruction a significant disclosure of vertical cracks in the middle of the span had been present. Our earlier experimental researches of strength and stiffness of splice connection of reinforced concrete foundation and concrete footing with rigid reinforcement showed the results, which also confirmed the need for ties or spiral winding around the metal profile. Since spirals (ties) in the experiment were not used, an  at failure there was the loss of bond stress and a test element was split along the axis of the rigid reinforcement, which is shown in Figure 5 [2]. The destruction of all beams reinforced with I-beams No. 24, was basically the same, characterized by a sharp opening of vertical cracks, their development up o the height of the rib and at the bottom of the slab, and finally the destruction of the compressed zone of concrete in the middle part between the points of application of loads. The nature of beams failure and the results of train measurements showed that at high profiles of I-beams, setting the top flange in the compressed zone of the concrete, as well as at short profiles connected with the compressed area of concrete by ties, rigid armoring acts with the concrete. [1] In the experiments carried out by Central Scientific Research Institute of Construction the fracture practi-cally always occurred at sharply defined yielding of the metal not only in the bottom I-beams flanges, but also in the wall of the rolled metal. In the beams reinforced with I-beams №12 and ties it is obvious that the entire pro-file cross section reached the yield point. Although in the beams with short profiles without ties thefailure was characterized by a shear of a concrete web along the upper flanges of I-beams, by that time the reinforcement stress had also been quite high and for the beams with reinforcement anchoring had apparently reached t  yield point. In all of the above samples the height of the compressed area was less than 0.5 and the beginning of the failure in all the cases was  really determined by the yielding of the metal (but for the samples with an early fail-ure due to the shear fracture). Weld bead 3 mm MATERIALS OF VIII JUNIOR RESEARCHERS’ CONFERENCE                                                    2016 Architecture and Civil Engineering  68  Fig. 5. General view of the foundation block experimental sample reinforced with the help of a rigid rod - I-beam (welded of U-profiles № 6,5)  REFERENCES  1. Васильев, А.П. Железобетон с жесткой арматурой // А.П. Васильев, А.А. Гвоздев ; под общ. ред. Г.И. Берди-чевского. – М., Л. : Гос. изд-во стр. лит., 1941. – 124 с. 2. Трубач, Ю.В. Экспериментальное исследование прочности и жесткости стыкового соединения железобетонно-го фундамента и набетонки с жестким армированием / Ю.В. Трубач, А.П. Кремнев, В.Д. Гринев // Проблемы современного бетона и железобетона. – Минск : Ин-т БелНИИС, 2014. – С. 151–163. 3. Васильев, А.П. Проектирование железобетонных конструкций с жесткой арматурой // А. П. Васильев ; под общ. ред. А.А. Гвоздева. – М. : Стройиздат, 1943. – 51 с. 4. Trubach, Y. Rigid reinforcement efficiency in strengthening of strip foundations / Y. Trubach, A. Kremnev // European and national dimension in research : Materials of VII junior researchers’ conference. In 3 pats. Part 3. Technology. – Novopolotsk, PSU, 2015. – P. 53–57.   UDC 624.15  THE PRINCIPLES OF BASES AND FOUNDATIONS CALCULATION CONSIDERING DEFORMATIONS ACCORDING TO THE NATIONAL AND EUROPEAN STANDARDS  TATSIANA VIALIUHA, ALEXANDR KREMNIOV, NATALIA LOBAC HEVA  Polotsk State University, Belarus  The principles of bases and foundations calculation c sidering deformations in accordance with the national and European standards are provided. The limit state designs USL and SLS are considered according to the European standards. The similarities and differences of bases and shallow foundations calculation considering deformations in accordance with the national and European standards  are identi-fied and generalized.  In May 2015 the Republic of Belarus has officially become a participant of the Bologna Process. The par-ticipation in the Bologna process allows the higher education in the Republic of Belarus to be reformed accord-ing to the global and European tendencies. Thus, nowadays the harmonization of national and European design standards is of current interest. The Eurocodes introduction in the Republic of Belarus may increase the inflow of foreign investment in construction, therefore one of the main issues nowadays is Eurocodes developing and the ability to use them in practice. Eurocodes are the normative documents in the construction sector, developed by the European Committee for Standardization and recommended for use in accordance with the national characteristics by the European Union member countries. The National Annexes to the Eurocodes provide the additional requirements for the construction individual parameters, which can be higher, but not lower than the common European ones. Each country defines these requirements independently. In Europe a common approach in geotechnical design has 't been developed yet. The National normative documents [1, 2] as well as Eurocode 7 [3] decree the design of various objects according to the two groups of limit states (depending on the bearing capacity and deformation) and have  uni-

Methods of providing combined action of concrete and metal rolled stock in reinforced concrete constructions with rigid armoring

https://elib.psu.by/bitstream/123456789/37190/1/65-68.pdf

Methods of providing combined action of concrete and metal rolled stock in reinforced concrete constructions with rigid armoring

Abstract

Similar works

Full text

Available Versions

Digital Library of Polotsk State University (Репозиторий Полоцкого государственного университета)