Research On Seismic Performance Of Ultra-High Performance Concrete Columns And Fream Structure | Posted on:2021-05-13 | Degree:Master | Type:Thesis | Country:China | Candidate:T Qi | Full Text:PDF | GTID:2492306470988179 | Subject:Structural engineering | Abstract/Summary: | PDF Full Text Request | Ultra high performance concrete(UHPC)is a new kind of cement-based composite materials.It has higher compression strength,better ductility performance and more excellent durable performance.More and more researchers were interested in it.This paper is aimed to study the semismic performa nce of UHPC columns and UHPC fream structure by the theoretical derivation,regression analysis and numerical simulation,mainly including the following contents:According to the statistical test results,the consititive model of UHPC confined by stirrup was proposed by regression analysis and theoretical derivation.The finite element model of UHPC columns was established to perform variable parameter analysis.Results show that stirrup spacing and stirrup type have a significant impact on the bearing capacity and deformation capacity of UHPC column.The smaller the stirrup spacing is,the higher the bearing capacity of UHPC column is and the better the deformation capacity is.And moderate steel fiber can improve the deformation capacity of UHPC column.The finite element model of UHPC columns subjected to cyclic loading was established and the nonlinear finite element analysis is carried out.The finite element model of UHPC columns can accurately simulate its hysteretic behavior by comparing with the experimental results.In order to research the effect of axial compression ratio,shear span ratio,stirrup spacing and the volume of steel fiber on seismic performance of UHPC column,variable parameter analysis was carried out.Results shown that axial compression ratio and shear span ratio has a significant influence on hysteresis performance of UHPC column;in a certain range,the peak load increases with the increase of axial pressure ratio,while the ductility performance significantly decreases.The smaller the shear span ratio is,the greater the peak load is,and the worse the deformation capacity is.Stirrup spacing and the volume of steel fiber also has a certain influence on hysteretic performance of ultra-high performance concrete columns.According to the plane section assumption and oblique section stress analytic theory,the calculation model of the flexural and shear capacity and the calculation formula of the top horizontal displacement of UHPC column caused by bending deformation are proposed respectively by combining with the characteristics of UHPC material and the curvature distribution of UHPC column.The column top horizontal displacement caused by bond slip deformation and shear deformation were determined by Sezen model and classical truss model;and the restoring force model of UHPC column was proposed by regression analyzing of the download section stiffness based on the four-fold line restoring force model.Results show that the proposed flexural and shear capacity calculation model and the top horizontal displacement calculation formula and restoring force model agree well with the experimental results.The six-story and nine-story reinforced concrete frame structure models were built and the elastic-plastic static analysis and dynamic time-history analysis were carried out to determine the location of weak layer,providing a basis for the design of UHPC frame structure.And the seismic vulnerability of the UHPC frame structure is analyzed based on the limit state determined by the code definition and the seismic capability of the structure.In addition,the collapse resistance of UHPC frame structure was quantitatively evaluated based on the incremental dynamic analysis method.Results show that: the limit state determined by the seismic capacity of the structure can better reflect the seismic performance of the UHPC frame structure.UHPC frame structure can significantly reduce the failure probability o f the structure and improve the collapse resistance of the structure. | Keywords/Search Tags: | Ultra-high performance concrete (UHPC), constitutive model, flexural capacity, shear capacity, defoemation capacity, restoring force model, UHPC frame structure, seismic vulnerability analysis | PDF Full Text Request | Related items |
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