EP1331320A1

EP1331320A1 - Precast prestressed concrete beam with steel members

Info

Publication number: EP1331320A1
Application number: EP02386018A
Authority: EP
Inventors: Mantzaris Ioannis
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-01-17
Filing date: 2002-12-30
Publication date: 2003-07-30
Also published as: GR20020100023A; GR1004450B

Abstract

The product.

Composite recast prestressed consrete beam with steel truss. Application in bridge and building construction. The bottom prestressed concrete flange (No 1) and the steel truss (No 2 and 3) are the static elements for the A' phase (dead load of initial precast beam and in situ concrete).
The B' phase is the formation of the final section, after strengthening of the additional concrete (No 4).
This beam, is produced in factory and then transported and erected into his final position.
In situ is completed with steel reinforcement and poured.

The method.

Use of steel truss instead of classic scaffolding. This truss in incorporated inside the concrete in the factory.
The bottom flange of the beam ARCULYS, remains as a part of the final beam.
The top flange, can remain or taken out, after the strengthening of the final beam.

Description

It is a new product with combination of precast prestressed concrete and steel construction. The application field is bridges and building construction.
Thiw product that is called abbreviated "ARC OF ULYSSE" or ARCULYS proposes a new method for construction of concrete works.
This method consists on the use of a steel truss in combination with the prestressed concrete section.
a) The steel truss has a provisory function assuring the stregth of the total beam till the rest of the concrete is poured and then the total concrete section assures the strength for all the remaining loads.
b) The steel truss is part of the final section.
The existing level of knowlogy today is:
For the product.
Precast prestressed concrete beams, produced in factory or in situ and then transported and erected in their final position.
Afterwards, in situ concrete is poured and after the strengthening of this supplementary concrete, the beam is ready for use.
Disadvantages.
a) Because of the weight of the beam, it is a limit in spans. Also, because of the road network.
b) The precast beam takes for his self weight an important part of the strength, letting only the rest for the live loads (traffic loads).
For the method.
We have already described the method of precast elements.
The classic method the very well known, is the position of scaffoldings on the ground then the position of the mould and concreting. After strengthening of the concrete (about 28 days) scaffolding is taken out.
Disadvantages.
a) When scaffolding is used, the space under the construction is occupied, which is disturbing especially for traffic under the construction. Also, is very difficult when natural obstacles exist (rivers, cliffs etc).
b) Construction time is very long.
c) The work in situ is more difficult and the quality is less than with method precast because the maximun part is fabricated in factory under full control and under the best conditions.
Explanation of figures.
Figure 1 (simple beam) and 2 (double beam) presend section of the beam at the initial phase.
Figure 3 presents views of the beams with different types of trusses.
Figure 4 presents types of beams at final phase, after concreting of the supplementary section.

1. Precast concrete produced at the factory.
2. Web of the steel truss.
3. Upper flange of steel truss.
4. In situ concrete.

This invention diminishes the disadvantages by using the following technic.
The top compression member, is a steel section supporting all the loads till the formation of the final concrete section.
That means, it supports the load of the initial factory made beam (self weight) and the loads of the concrete in situ for the formation of the final section.
When the final concrete section is formed and strengthened, the steel section (No 2 and No 3) doesn't work any more. And can be taken out, or remain as part of the concrete section. A variation is to use the steel truss as the final resisting section, without concrete.
The beam has the following parts:
a. The bottom flange is prestressed concrete section (No 1). After the initial prestressing, it is possible to apply additional prestressing. This can be pre-or post-tensionning or exterior cables. The additional prestressing (in situ) is also very useful for the jointing of "segments" for the formation of beams of important length.
b. Steel truss with strong top flange (No 2). The top flange, initially is under tension because of the prestressing of the bottom concrete flange. After that is compressed till his permissible limits, because of the load of the in situ concrete.
The top flange, after the strengthening of the final section, either remains inside the concrete section, or is taken out.
In case that the top flange will be taken out and be used again, is preferable to be positioned higher than the top concrete level.
The truss can be horizontal or arch shaped (No 3).
Concerning the construction method, the new element is the following:
a) In the classic method the scaffolding is under the concrete beam, supported by the ground. In the proposed method the truss is positioned on the top of the concrete beam, letting free the space under.
b) The bottom prestressed concrete flange, is the working level for the additional in situ pouring.
c) The bottom flange hase a double static use.
It is the bottom flange of the provisory steel truss, and also it is the bottom flange of the final concrete beam.
Is to be noted that the beam ARCULYS can be used independently us definitive and final beam.
The invention hase the advantages:
a) Very important production potential
b) Small weight of the initial element
c) Possibility for segmental construction
d) Possibility for continuous beam.
e) Possibility for caisson bridges.

Claims

The product.
The precast concrete beam ARCULYS is a composite concrete and steel construction, and his characteristic is the top flange (No 3) and web (No 2) by steel truss and the bottom flange (No 1) by precast prestressed concrete. Is produced in factory either in full length or in segment jointed in situ. The steel truss can remain permanently inside the concrete or taken out after the strengthening of the final concrete section (No 4).
The method.
This precast prestressed concrete beam with the steel truss, it is the tool for a new concreting method for civil engineering works.
It is characterized by the fact that the steel truss, is the provisory support (not supported by the ground as the classic scaffolding) and can be taken out after the strengthening of the final section.
The bottom prestressed concrete flange is the provisory bottom flange of the truss also the provisory working level (or mould) but also, the definitive bottom flange of the final beam.
The system.
The combination of the beam with the method of construction consists a new construction system very useful for the construction of bridges and industrial buildings of important spans.