摘要(英) |
Since
Taiwan is located on seismic belt with typical subtropical maritime
climate, the assessment of the safety of structures is a very important
issue for structures erected in this country. The safety of the
infrastructure is so vitally interrelated with the society that the
quality of construction and the expected service life should be
reasonably evaluated to ensure the life and property of the society. A
nondestructive testing evaluation can be a highly-effective,
nondestructive, and repeatable technique. Methods based on the
propagation of transient elastic waves are highly mature measuring
techniques as have been applied to the testing of non-homogeneous
concrete material. With the physical quantities gained from impacting
the surface of the structure, the nature of the material, the geometry,
and the characteristics and locations of the inner flaws could be
evaluated. Without destructing the structure, the testing result can
offer valuable information to secure the construction quality and
structural or material durability. This study first
reviews related elasticity theories concerning the wave propagation and
dynamic responses due to impacts on the concrete structural members,
then demonstrates numerical models for various structural members with
different geometric boundaries using the finite element method, finally
carries out experiments on specimens and makes further analyses and
comparisons with the numerical results. It is intended for this study
serving as a reference to the wave propagation of structural members for
novices in this nondestructive testing field. Moreover, the experienced
researchers may also find it useful in providing some clues of related
theories. The study shows that the characteristics of the boundary
signals can be effectively revealed by the finite element simulation.
Nevertheless, by parametric studies on properly selected physical
quantities and generalization of characteristics of specific parameters,
it can potentially provide engineers with useful rule of thumb. |