SU1633068A1 - Method of prestressing flange beams - Google Patents

Abstract

The invention relates to the construction and can be used in the beam structures of industrial and civil buildings. The purpose of the invention is to increase the bearing capacity of the beam. In the manufacture of a pre-stressed beam, the wall 1, the upper and the lower section are placed on the feed roller table and are placed in the design position. They are then delivered to the welding cage 5, where the welding of seams is performed, and the beam gradually enters the receiving roller table 6. In front of the welding cage B, heating elements 7 and 8 are installed, which heat the wall and the bottom section so that the bottom panel elongation em 5-70% of the wall elongation value. 1 hp f-ly, 5 ill. With Ј

Description

& with

Ј0

s & x

1

The invention relates to the construction and can be used in the beam structures of industrial and civil buildings.

The purpose of the invention is to increase the bearing capacity of the beam.

Figure 1 shows the assembly of the beam; Fig. 2 shows a plot of reactive welding stresses due to the conditional shrinkage forces arising in welds; Fig. 3 shows the stress diagram from the preliminary elongation of the wall; Fig. 4 shows the diagram from the preliminary elongation of the pressure; Fig. 3 shows the initial stress diagram from the joint action of welding, pre-wall extension and pre-wall extension.

The method is carried out as follows.

Wall 1, upper c 2 and lower c 3 are placed on the feed roller 4 and are positioned relative to each other in the design position. They are then delivered to the welding cage 5, where the welding of seams is performed, and the beam gradually enters the receiving roller table 6. In front of the welding cage B, heating elements 7 and 8 are installed, which heat wall 1 and bottom, respectively, from 3. Wall and as a result of heating, the lower porous is elongated in the free direction (opposite to the welding adhesive) and in this state they are combined into one solid with the upper seal. After the structure has cooled down, the initial stress diagram is formed directly in it.

The wall and the bottom along the beam are pre-elongated by heating, and the amount of preliminary elongation of the bottom cus is chosen within 5 -70% of the value of the wall pre-elongation so that after the beam is assembled, the sum of the preliminary and welding stresses at the bottom edge of the wall to zero. The amount of preliminary elongation of the lower sa, in particular, is determined by the formula

FH n l2 + 1l b§ilai1li} I

° p.N I nUa + T) baJ + 6a- (a + 1)

, -4 - “n ()}

Q, -

0

where a

I

st

3a (a: 1) ba-Za + TJ3 ™

Ј - the value of the preliminary

wall extension; h

asymmetry coefficient;

| 2

t

ha

sn

BUT

the ratio of the area of the wall to the area of the whole section; heat of welding energy for seams, J / cm; cross-sectional area. The proposed method allows to obtain an optimal state of the wall by using the effect of welding on the stress state of the structure, bending the beam.

Claims (2)

1. A prestressing method for an I-beam by extending the beam wall along an axis and then attaching a joint to it, characterized in that in order to increase the carrying capacity of the beam, the elongation is carried out by heating the wall and the lower flange of the beam so that the magnitude of the lower elongation of the bottom strip is 5-70% of the magnitude of the elongation of the wall. 2. Method pop.1, characterized in that the amount of elongation of the lower part of the ca is determined by the formula p ".p (5 + l2i5j Cnu 2-m (a + 1) JЈ6a5V6a- (a-Hy5m X R n ten BUT g 7 ; pc + 1)}, 45 where a is the asymmetry coefficient of the cross section: РсгЗа (а-1) 6- (а-н72ш 0  mon the value of the preliminary elongation of the wall; m is the ratio of the area of the wall to the area of the whole section A; 8P - heat absorbed by heat from seams, J / cm.  9% p u / voad zog ue-u Z gpf 3 / L 8cheoech1 / -Ј T LV Jlv ® I eat t rwakt fiH.H °, FIG 4 Mr. pn.n NT L JOB . п ™ п.н &