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.

CALCULATION OF A MONOLITHIC COLUMN FOUNDATION FOR A REINFORCED CONCRETE COLUMN OF A MULTI-STOREY BUILDING IN LVIV

Problem statement. In modern construction of residential and commercial buildings, bridges and other structures, columns are often the main load-bearing elements. Different in the way they are manufactured and in their characteristics, these building elements serve as the basis of the framework on which all other building structures are placed. However, in order to have a strong, durable and, most importantly, correct construction of the whole structure, the columns should be installed with minimum deviations from the design values. This is why a great deal of attention is paid to the foundations in the design and implementation of the project. The purpose of the article is to develop a calculation of a monolithic column foundation for a reinforced concrete column of a multi-storey building in Lviv based on theoretical research. The design is based on theoretical studies and is based on the design of a monolithic column foundation for a multi-storey building in Lvov, taking into account the dimensions of the foundation, the soil characteristics, the self-weight of the foundation and the longitudinal reinforcement coefficient. Analysis of publications. Studying not only foreign, but also domestic current theoretical developments and practical experience will allow the objective to be achieved. There are examples among European countries that largely meet the current requirements. Results of the study. The most common soils in Lviv are chernozem, eluvial and peat-bog soils. The climate in Lviv is moderately continental with mild winters and warm summers. With these data, the dimensions of the monolithic columnar foundation for a multi-storey building are calculated and its reinforcement is determined. The strength of the monolithic columnar foundation for the reinforced concrete column of the multi-storey building is tested for the punching strength. Based on the results of the calculations, it is determined that the foundation is sufficiently strong under the column.Conclusions. In this article, the characteristics of soils and climatic conditions of the construction area in the city of Lviv were investigated. The dimensions of the foundation's underside, all dimensions of the foundation and the pressure on the ground under the underside from the design load were calculated. The reinforcement area of the foundation footing was selected and the strength of the foundation was tested for push-through.

Research of changes in the parameters that affect the rigidness of the column-foundation joints

Introduction. The existing types of connection assignment in the design scheme — hinged and absolutely rigid joints — do not reflect the actual operation of the connection. The lack of calculation of the actual rigidness of joint and its failure to take into account in the design of the frame can lead to a different distribution of efforts from the calculated one and an increase in the movement of the frame elements. The purpose of this work is to researching the influence of the change size of the elements forming the column base on its rotational rigidity. Materials and methods. The calculation of the transverse frame was performed in the Dlubal RFEM software package. The calculated efforts acting in the lower section of the column were transferred to the calculated models of the column base, made in the IDEA StatiCa software package, in which the further calculation of the joint rigidness was performed. Results. The rotational rigidness of the joints with different structural solutions of the column base is determined. The change in the rigidness of the connection between the column and the foundation with an increase in the thickness and height of the support ribs is analyzed. Based on the calculations, graphs of the identified dependencies are constructed. As an example of strengthening the base of the column, the introduction of a traverse was proposed. The article considers six variants of the traverse device, and variants with three support ribs and with traverses, but without support ribs. The calculated rigidness of the column bases is summarized in graphs, where it can be seen that the metal adding is effective only up to a certain point. Variants of the arrangement of column bases with additional transverse ribs are considered. Conclusions. The greatest contribution to the increase in the rotational rigidness of the joint is made by the addition of a traverse. By increasing the thickness or height of the introduced traverse, it is impossible to achieve absolutely rigid fixing, it is necessary to change several parameters in a complex way. The introduction of additional ribs located outside the plane of action of the moment practically does not affect the rigidity of the joint.

Behaviour of Precast Column Foundation Connection under Reverse Cyclic Loading

Precast column foundation connection is one of the critical connections under reverse cyclic loading, and the present study focuses on this connection. Three types of connections were considered, such as (i) base plate connection, (ii) pocket connection, and (iii) grouted sleeve connection. All the above connections were designed, and experimental investigation was carried out on 1 : 2 scaled models by subjecting the column to lateral reverse cyclic loading. Displacement-controlled loading pattern has been adopted for the testing of the specimens. The structural response of the connection was studied for their (i) load-displacement hysteresis behaviour, (ii) stiffness degradation, (iii) energy dissipation, and (iv) ductility. The results were then compared with that of the monolithic connection. The precast connection was more ductile, and the energy dissipated by the pocket connection was high compared to the base plate and grouted sleeve connection. The ductility and the load-carrying of grouted sleeve connection were small compared to other connections. The results of the study showed the precast column foundation can be used in seismic prone areas.

EXPERIMENTAL AND NUMERICAL STUDY ON COLUMN-FOUNDATION CONNECTION THROUGH EXTERNAL SOCKET

In practice, bridge foundations and pier columns are usually constructed with cast-in-place concrete. Precast columns are currently widely used in highway bridges in China, which can save construction time and improve concrete quality. The connection between precast bridge columns and the foundation can affect how forces transfer from one to the other. This paper investigates using external sockets to form a connection between the bridge column and foundation. This method can accelerate the bridge construction time with the additional advantages of improving the orientation and creating a large erection tolerance. Two types of connections are presented and tested to investigate the behavior of the column-foundation connections and find a more suitable way to use external socket connections. The experimental results show that the column-foundation connection design satisfies the design requirements. The results also show that roughening the column surface within the external socket is more effective at connecting the column to the foundation when using an external socket compared to attaching a steel plate on the column. The experimental results are validated with a finite element analysis, resulting in a proposal regarding the column-foundation connection behavior as well as design recommendations for the external socket connection.