Supporting Capacity Analysis and Construction Scheme Optimization of Support System for Cast-in-Situ Box Girders in High-Pier Wading Bridges
Although a concrete bridge support system is a temporary structure,it still has a supporting capacity.With the development of bridge engineering,concrete bridges with high piers and long spans are gradually applied in deep reservoir areas,and the forces on scaffolding are more and more complex.Traditional manual calculations in structural mechanics can no longer completely reflect the stress-strain states of scaffolding with irregular configurations,special parts,and uncommon conditions.Thus,it is necessary to use a numerical method to calculate the supporting capacity of scaffolding and design construction schemes.This paper took a concrete wading bridge with high piers as an example.An evaluation method based on the finite element method with the Midas civil software is proposed for analyzing the safety of a support system from the aspects of strength,rigidity,stability,and cost-effectiveness.The results show that although disc-type full scaffold structures are simple in construction,with low steel consumption,various stand bars,uniform stress distribution,and small deformation(a maximum deflection of only 2.82 mm),their strength and stability are not as good as beam support systems.In addition,they have higher requirements for sites.Therefore,when disc-type full scaffold structures are applied to high-piers and large-span bridges,buckling analysis should be carried out on the whole model to prevent instability and collapse.Conversely,beam support systems usually do not suffer from strength and stability failures and have few requirements for sites.However,they are difficult to construct and require high steel consumption.Furthermore,deformation is increased due to the lack of vertical support in the midspan.Therefore,form-finding analysis must be carried out strictly when they are applied to complex bridges involving the"pre-camber"problem.In addition,on the premise that mechanical indexes are met,measures can be taken to achieve higher cost-effectiveness,such as adjusting the net distance of Bailey beams and strengthening lower chords.In this case,the net distance was adjusted from 80 to 100 cm,which can save about 10%in steel consumption.
bridge engineeringdisc-type full scaffold structurebeam support systembailey beamfinite element method
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