| The key to the sustainable development of the construction industry is the modernization of the construction industry,and prefabricated buildings are one of its main forms.However,the development of prefabricated buildings in my country is late,and there are potential safety hazards in the process of component fabrication and assembly.Improper handling of joint surfaces will lead to problems such as cold seams and reduce component reliability.The relevant codes in my country have not deeply explored the influence of joint surface treatment quality on the bearing capacity of laminated components,while European and American codes have clear classification treatment and friction coefficient requirements for joint surface roughness.Therefore,studying practical calculation methods,effective processing techniques,accurate detection methods and scientific evaluation systems is an important guarantee to ensure the safety and quality of prefabricated buildings.The main research content and results of this paper are as follows:1.Through literature research,sort out the joint surface roughness treatment process commonly used in engineering,and compare each process in combination with industry standards and engineering applications;sort out a large number of researches on concrete roughness detection methods by domestic and foreign scholars,and point out that traditional detection methods The limitations of concrete joint surface roughness parameters;summarize the latest theories and methods for the evaluation of joint surface roughness parameters,screen out roughness characterization parameters that can be used for reference,and establish a theoretical basis for the research on the evaluation indicators and methods of concrete joint surface roughness.2.At the material level,design 330 jointed specimens and 30 integral cast specimens,consider factors such as concrete strength grade,rough treatment process,and shear force direction,and use self-designed shear test fixtures to conduct shear strength tests.The change law of parameters such as cohesive force and internal friction angle of concrete joint surface under different treatment processes was obtained.The results show that: increasing the strength of the post-casting concrete does not significantly increase the shear strength of the jointed specimens;the cohesion of the three jointed specimens differs significantly,the roughened specimens reach 85.5% of the whole poured specimens,and the steel bar indentation specimens(45.6%)is slightly higher than that of the roughened specimen(39.1%);the roughened specimen with the best rough treatment effect still has a large gap with the cast specimen.3.Obtain the shape information of the concrete joint surface based on laser scanning technology,intercept the two-dimensional contour curve of the roughened joint surface,conduct quantitative analysis through the MATLAB calculation program,and obtain the roughness characterization parameters based on statistics and fractal theory;perform characterization parameters Correlation analysis with shear strength,formulate standard contour curves to verify parameter reliability,and study multiparameter hierarchical quantitative evaluation methods.The results show that: the roughness parameters obtained by the MATLAB calculation program are accurate and effective;the fractal parameters D of the punching specimens are very close,indicating that the morphology characteristics of the joint surfaces are highly similar,and there are only differences in degree;the roughness can be divided into very smooth There are four grades of,smooth,rough and very rough,and determine the combined roughness coefficient BRC of each contour line.4.At the component level,through the static tests of 10 composite beam and 2monolithic beam,the impact of the roughness of the joint surface,the height,and the presence or absence of stirrups in the bending-shear zone on the bearing capacity of concrete composite beam members,The impact of deflection and crack distribution on performance;verify the feasibility of the quantitative evaluation method for the roughness of the concrete joint surface,and quantitatively evaluate the influence of the joint surface roughness on the mechanical performance of composite beams.The results show that increasing the height of the joint surface has little effect on the shear capacity and deflection development of the composite beam,but it can effectively delay the cracking of the joint surface of the composite beam.When the joint surface is not well treated,the failure mode of the beam will change,and the horizontal slip cracks on the joint surface cannot be prevented;the recommended formula for the shear capacity of composite beams in GB 50010-2010 is corrected based on the roughness of the joint surface,and the calculation error Within 15%;the quantitative evaluation method of concrete joint surface roughness classification can quantify the weakening effect of the joint surface roughness on the mechanical performance of composite beams. |
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