Building Structural Damage Vibration Diagnostic Studies

The civil engineering field has been distressed by building quality problem for a long time. Both old buildings and new constructures made of inferior material urge us to erect a set of perfect quality detecting and on-line monitoring system, ensuring people against danger and economy growth against failure.The traditional static testing which has a precise result only can be carried out in lab for a long period and can't meets the demands of on-line detecting and monitoring.With the developing of testing technology and apparatuses, nondestructive testing which is handy, direct and nondestructive is widely applied in civil engineering. Many modern science and technology have been used in concrete nondestructive testing, which promote the nondestructive testing towards systematization and standardization. Research workers in all countries are devoting themselves to improving strength testing precision, developing non-strength testing and turn their attention from static quality assessing to quality assessing in building process.Nondestructive testing technology includes medium detecting technology and dynamic testing technology which make use of vibration respond of constructure and system dynamic behavior to detect damage in structure. Dynamic testing technology is significant not only for the assessing of structures, but also for its economy and convenience, which contains modal parameter identification, extracting and analizing damage indices, determining location of damage, quality assessment and life estimation. Extracting damage indices is the key to the study whose sensitivity determines the results of testing.Because of the dispersion of concrete's nature and complex of structure, we must overcome many difficulties when we applied dynamic testing technology to civil engineering field. In view of existing situation, author of the paper investigates the problems lie in building quality and choose concrete cantilever with a damage as typical example which is detected by damage indices through digital simulation. On the base of above testing results, several new damage indices are derived which are more sensitive and could be used in practice.