Research On The Bending Performance Of Prefabricated Narrow Width Steel Box Composite Beams

The steel-concrete composite girder bridge can give full play to the material properties of steel tension and concrete compression.It has the advantages of high bearing capacity,high stiffness,light weight and high degree of assembly,and has been widely used in engineering construction.The steel girders of steel-concrete composite girder bridges commonly used in China are mostly steel plate girders or channel steel box girder structures with good technical and economic performance.With the increase of social labor cost in recent years,the superior economic performance of the channel steel box composite bridge is no longer significant due to the complex arrangement of stiffeners.On the basis of the steel box section of the channel steel box composite beam,the narrow steel box composite beam converts the open section of the channel steel box into a closed section by reducing the web spacing and increasing the upper flange steel plate,thereby reducing the number of stiffeners and diaphragms,enhancing the section stiffness during the construction phase,and shortening the construction period.At the same time,the steel box section of the narrow steel box composite beam with a smaller transverse section is more suitable for assembly and industrial construction.The narrow steel box composite beam of the assembled bridge deck has a better application prospect than the narrow steel box composite beam of the cast-in-place bridge deck.Combined with practical engineering applications,this paper proposes a fabricated narrow steel box composite beam bridge structure.Based on practical engineering applications,this paper conducts a systematic study on the bending performance of prefabricated narrow width steel box composite beam bridges using model experiments,numerical simulation,and theoretical analysis methods.The main work and conclusions completed are as follows:(1)Based on model tests of prefabricated narrow steel box composite beams and cast-in-place narrow steel box composite beams using UHPC wet joints and UHPC shear slots,the main mechanical properties of the two test beams,including failure process,failure mode,and ultimate bending bearing capacity,were studied.The difference in bending performance between prefabricated narrow steel box composite beams and cast-in-place narrow steel box composite beams was obtained.The experimental results show that the collapse failure positions of the new prefabricated narrow steel box composite beam are all located within the concrete precast slab.The bending stiffness,bending bearing capacity,and mechanical performance indicators displayed during the test process of the new prefabricated narrow steel box composite beam are similar to those of the cast-in-place narrow steel box composite beam,indicating that the new prefabricated narrow steel box composite beam has the same bending performance as the cast-in-place narrow steel box composite beam.(2)Based on the bending response law of the model test beam,a numerical analysis model for plastic damage of narrow steel box composite beams was established.The numerical calculation results are in good agreement with the experimental results,and the numerical model can better reflect the entire bending behavior of the test beam.By using numerical analysis methods and changing material and structural parameters,the influence of UHPC compressive strength,web height,web thickness,and flange width on the bending performance of prefabricated narrow width steel box composite beams was obtained.(3)Formulas for calculating the bending bearing capacity of narrow steel box composite beams under normal service limit state and bearing capacity limit state have been established,and comparative analysis has been conducted with experimental results.The results show that the theoretical formula for calculating the bending bearing capacity of narrow steel box composite beams established is in good agreement with the experimental results,and the established formula can be used for calculating the bending bearing capacity of narrow steel box composite beams.(4 Based on physical engineering,the bending performance of prefabricated narrow width steel box composite beam bridge during the construction stage was calculated and analyzed,and the mechanical and economic performance differences were compared and analyzed with slot steel box composite bridge.The results show that during the construction process,the bottom plate stress,top plate stress,and deflection of the narrow steel box composite beam bridge are all smaller than those of the channel steel box composite beam bridge.At the same time,the narrow steel box composite beam bridge has significant advantages in economic indicators such as concrete,steel consumption,and coating area.Taking into account the cost of measures and construction during transportation and lifting,the narrow steel box composite beam bridge has a high technical and economic performance advantage.