The Stress Wave Of Reinforced Concrete Structures And Its Application

Reinforced concrete structure by steel bar is the engineering unit structure of grouting,and widely used in civil engineering applications because its good durability and fireresistance, and low cost and so on. Reinforced concrete structure quality directly affects thesecurity and durability of the construction. What is more, the grouting inspection of reinforcedconcrete is critical to eliminate hidden peril in quality and ensure life-span of the engineeringstructure. Stress wave detection is the main method for grouting quality nondestructive testing,and the stress wave propagation rules in the reinforced concrete is helpful to design the testingscheme and analysis detect date. The main contents and conclusions are as follow:(1) The effect of the grouting type and grouting diameter on stress wave propagation wasstudied. Two models about grout type and grouting diameter were established by the finiteelement software of LS-DYNA. The results showed that, the consolidating wave speed andaverage amplitude ratio all increases with the grout type increasing, and decreases with theincrease of the diameter of the grout; The consolidating wave speed varies from4200m/sto4750m/s and average amplitude ratio increases from0.15to0.65when the grout typechanges from C20to C70. On the other hand, the consolidating wave speed decreases from4650m/s to3950m/s and the average amplitude ratio decreases from about0.9to0.13withthe grouting diameter increasing from100mm to220mm.(2) The effect of propagation characteristic of half missing grout and complete missinggrout on stress wave in reinforced concrete structure. The finite element software ofLS-DYNA was used to simulate and analyze the effect of missing grout on the excitation ofthe stress wave. The results showed that, the consolidating wave speed and average amplituderatio at which stress wave propagates in the two models. The results demonstrate that theconsolidating wave speed in the range of4220m/s to4750m/s in case of half missing grout,and increases with the increase missing grout size, in addition, average amplitude ratio at0.52to0.75and increases with the increases of size of missing grout; the consolidating wave speedin the range of4250m/s to4850m/s in case of complete missing grout, and increases with theincrease missing grout size, in addition, average amplitude ratio at0.32to0.7and increaseswith the increases of size of missing grout.(3) Reinforced concrete structures grouting quality is always demarcated through thevelocity of consolidation wave. The reinforced concrete structures grouting quality is dividedinto four grades (A, B, C and D). Test model of different grouting quality grades weredesigned by experiment to get the consolidating wave speed, and then it was found that the experimental results agree well with numerical simulation results through finite elementanalysis. Finally, by means of comparing the numerical result and experimental result, weproposed a approach that aim to utilize the velocity of consolidation wave to calibrate thegrouting quality of reinforced concrete structures: the velocity of consolidation wave for Ashould be less than4400m/s; for B, in the range of4400m/s to4500m/s; for C, in the range of4500m/s to4600m/s; for D, greater than4600m/s.Through the study of this paper, it can be contributed to the application and analysis ofthe detection of reinforced concrete structure grouted quality.