The use of new technologies in civil construction market grows every year. In order to supply
the needs of this department, several products are presented in fairs and congresses as
alternatives to generate costs reduction in production and execution of building works. In
parallel, small industries of civil construction market provide a polymer-based (plastic) stirrup,
selling it through the internet, to use in the reinforced concrete beams and pillars as a
replacement for those made of steel, with the promise of costs reduction and the guarantee of
efficiency, according to data from national laboratories. But it needed to be confirmed, since
the applications in these structures are still unknown by the majority of professionals of this
area. Moreover, the brazilian standard on reinforced concrete, NBR 6118 (ABNT, 2014),
released by the Brazilian Association for Technical Standards, brings no reference to the
utilization of polymer-based stirrups. To check the mechanical properties and the safety of this
product, polymer-based stirrups with rectangular shape (100 mm x 250 mm) were used in
beams and tested at the Civil Engineering Laboratory located in the Federal University of Para.
A total of 7 reinforced concrete beams were made, having a cross section of 140 mm x 290 mm
and 2200 mm in length, 1 with steel bracket for reference, 3 with plastic stirrups and 3 with
steel and plastic straps alternating every 150 mm, 100 mm and 75 mm. The beams with plastic
stirrups had the same longitudinal reinforcement as the reference beam. The plastic stirrups
were used to study its behavior as shear reinforcement. The STUTTGART test setup was used
during the procedure. The experimental results obtained from the tests with plastic stirrups
indicate inefficient and unsatisfactory performance compared to conventional steel stirrups
since its contribution to withstand shear forces was practically negligible in relation to the
reference beam.
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