A damage detection method for complicated beam-like structures is proposed based on the subsection strain energy method(SSEM),and its applicability condition is introduced.For a beam with the continuously varying flex...A damage detection method for complicated beam-like structures is proposed based on the subsection strain energy method(SSEM),and its applicability condition is introduced.For a beam with the continuously varying flexural stiffness and an edge crack,the SSEM is used to detect the crack location effectively by numerical modal shapes.As a complicated beam,the glass fiber-reinforced composite model of a wind turbine blade is studied based on an experimental modal analysis.The SSEM is used to calculate the damage index from the measured modal parameters and locate the damage position in the blade model successfully.The results indicate that the SSEM based on the modal shapes can be used to detect the damages in complicated beams or beam-like structures for engineering applications.展开更多
Corrugated steel–concrete(CSC)composite structures are increasingly used in tunnel and culvert projects due to their good mechanical properties.The design of CSC composite structures is often governed by deflection l...Corrugated steel–concrete(CSC)composite structures are increasingly used in tunnel and culvert projects due to their good mechanical properties.The design of CSC composite structures is often governed by deflection limits in service,hence it becomes crucial to evaluate accurately their flexural stiffness.In this work,the deflection deformation mechanism of CSC composite structure is studied by experimental and numerical methods,and a simplified formula for calculating the flexural stiffness is established.In addition,the deflection results obtained by different methods are compared and analyzed.It is found that:(1)the flexural stiffness of the CSC composite structure is constant only when the load is small,and after the bending moment exceeds a certain value,the flexural stiffness will gradually become smaller as the bending moment increases.(2)The value of the bending moment corresponding to the end of the elastic stage of the bending moment-deflection curve increases with the increase of the axial force in the composite structure.(3)As the axial force of the composite structure increases,the flexural bearing capacity of the structure increases first and then decreases.展开更多
The variations in the viscoelastic characteristics of asphalt concrete due to testing mode are assessed and modeled in the present investigation.Asphalt concrete mixture was prepared at its optimum asphalt binder requ...The variations in the viscoelastic characteristics of asphalt concrete due to testing mode are assessed and modeled in the present investigation.Asphalt concrete mixture was prepared at its optimum asphalt binder requirement and compacted in slab mold with the aid of roller compaction.Beam specimens of 6.2 cm width,5.6 cm depth,and 40 cm length,were obtained from the slab samples with the aid of a diamond saw,and tested using controlled stress and strain techniques under dynamic flexural stresses.The viscoelastic properties such as the phase angle,cumulative dissipated energy,permanent deformation,flexural stiffness,and micro strain were monitored and modeled among the two testing techniques.It was noticed that higher micro strain and permanent deformation are detected when testing the asphalt concrete specimens under constant strain mode.However,higher phase angle,flexural stiffness,and energy dissipation could be observed under the constant stress mode of the test.展开更多
基金supported by the National Basic Research Program of China (973 Program)(No. 2007CB714603)
文摘A damage detection method for complicated beam-like structures is proposed based on the subsection strain energy method(SSEM),and its applicability condition is introduced.For a beam with the continuously varying flexural stiffness and an edge crack,the SSEM is used to detect the crack location effectively by numerical modal shapes.As a complicated beam,the glass fiber-reinforced composite model of a wind turbine blade is studied based on an experimental modal analysis.The SSEM is used to calculate the damage index from the measured modal parameters and locate the damage position in the blade model successfully.The results indicate that the SSEM based on the modal shapes can be used to detect the damages in complicated beams or beam-like structures for engineering applications.
基金funded by Shanghai 2020“Science and Technology Innovation Action Plan”Project,China(Grant No.20dz1202600)National Natural Science Foundation of China(Grant No.52090083)+1 种基金Science and Technology Innovation and Demonstration Project of Department of Transport of Yunnan Province,China(Grant No.[2020]106)The authors gratefully acknowledge their financial supports.
文摘Corrugated steel–concrete(CSC)composite structures are increasingly used in tunnel and culvert projects due to their good mechanical properties.The design of CSC composite structures is often governed by deflection limits in service,hence it becomes crucial to evaluate accurately their flexural stiffness.In this work,the deflection deformation mechanism of CSC composite structure is studied by experimental and numerical methods,and a simplified formula for calculating the flexural stiffness is established.In addition,the deflection results obtained by different methods are compared and analyzed.It is found that:(1)the flexural stiffness of the CSC composite structure is constant only when the load is small,and after the bending moment exceeds a certain value,the flexural stiffness will gradually become smaller as the bending moment increases.(2)The value of the bending moment corresponding to the end of the elastic stage of the bending moment-deflection curve increases with the increase of the axial force in the composite structure.(3)As the axial force of the composite structure increases,the flexural bearing capacity of the structure increases first and then decreases.
文摘The variations in the viscoelastic characteristics of asphalt concrete due to testing mode are assessed and modeled in the present investigation.Asphalt concrete mixture was prepared at its optimum asphalt binder requirement and compacted in slab mold with the aid of roller compaction.Beam specimens of 6.2 cm width,5.6 cm depth,and 40 cm length,were obtained from the slab samples with the aid of a diamond saw,and tested using controlled stress and strain techniques under dynamic flexural stresses.The viscoelastic properties such as the phase angle,cumulative dissipated energy,permanent deformation,flexural stiffness,and micro strain were monitored and modeled among the two testing techniques.It was noticed that higher micro strain and permanent deformation are detected when testing the asphalt concrete specimens under constant strain mode.However,higher phase angle,flexural stiffness,and energy dissipation could be observed under the constant stress mode of the test.
