EVALUATION OF THE CARRYING CAPACITY OF REINFORCED CONCRETE WELDED ARMATURE JOINTS

Author:

Bolotov Gennadyi , Chernihiv National University of Technology (95 Shevchenka Str., 14027 Chernihiv, Ukraine)

Bolotov Maksym, Chernihiv National University of Technology (95 Shevchenka Str., 14027 Chernihiv, Ukraine)

Hanieiev Tіmur, Chernihiv National University of Technology (95 Shevchenka Str., 14027 Chernihiv, Ukraine)

Korzachenko Mykola, Chernihiv National University of Technology (95 Shevchenka Str., 14027 Chernihiv, Ukraine)

Language: ukrainian

Annotation:

Urgency of the research. The main of the technological process of buildings construction of precast or precast-monolithic reinforced concrete is the production of mesh reinforcement. The main scope of reinforced concrete works is in the welding operations. This is primarily due to the high welded joints quality compared with mechanical rebar splicing using the Lenton couplers.

Problem statement. At buildings construction by monolithic-frame technology for the rebar joint the arc welding processes is widely used. Besides, in addition to the above methods at the stationary conditions for reinforced frame escalating the contact flash-butt welding with continuous flashing or resistance welding is also used. The experience of flash-butt welding applying for a long period of time in the industrial construction conditions allowed to determine the basic advantages caused by the stable welds quality, the ability to automate the welding process, requires no additional consumables.

Actual scientific researches and issues analysis. The studies of the welded rebar joints operability are made by different researchers allowed to determine the basic requirements for the welding conditions, mainly related to the uniformity of heating and cooling, small isothermal holding time at high temperatures and, most importantly, weldability of rebar.

Uninvestigatigated parts of general matters defining. The building structures quality and reliability depends on not only the raw materials quality, but also, the culture of construction works including the welding.

The research objective. In this regard, the aim of this work is to assess the bearing capacity of welded armature joints of reinforced concrete by means of mechanical tests on break.

The statement of basic materials. The results of the studies of the strength characteristics of reinforced concrete welded armature joints made by flash-butt welding and arc welding in shielding gases are shown in the paper. The flash-butt welding performed in the following modes: сurrent density varied in the range of j = 60…160 А/mm2; isothermal holding time t = 0,8…2 sec; heating effort Fh = 10 ... 20 MPa; rainfall effort Fr = 100 ... 150 MPa. Mechanized arc welding performed in the environment of CO2 on DC reverse polarity value of I = 130A.

Conclusions. It is established that the use of “soft” modes of preheated flash-butt welding provides the receipt of equally-strength with the limit of joints endurance at 639 ... 685 MPa, unlike the arc welded joints, the tensile strength of which didn`t exceed 516 ... 578 MPa, due to the considerable heterogeneity of metal structure and HAZ of the joints.

Key words:

armature, reinforced concrete, flash-butt welding, arc welding, the characteristics of strength

References:

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