混凝土层裂强度测量的新方法

提出了利用Hopkionson压杆测量混凝土层裂强度的新实验方法:用高聚物材料取代传统的金属材料透射杆，混凝土试件为细长杆，由于高聚物波阻抗比混凝土小，试件中压缩波在试件/吸收杆界面反射后形成拉伸波使试件产生层裂破坏，通过吸收杆上透射波形可以确定混凝土层裂强度。由于波在粘弹性材料中的弥散效应，吸收杆中透射波形会发生变化，但三维有限元分析表明，在利用吸收杆上透射波确定混凝土层裂强度时弥散产生的影响可以忽略。按照一维特征线理论，可以由吸收杆上的应变波形确定出混凝土材料的层裂强度。

A novel experimental technique to determine the spalling strength of concretes

A polymeric buffer bar is employed to replace the conventional metallic transmission bar in a split Hopkinson pressure bar to determine the spalling strength of a long concrete rod that is placed between the metallic incident bar and the polymer buffer bar.Since the polymer bar material has a lower mechanical impedance than the concrete specimen,spalling can be produced in the concrete rod after the compressive wave in the concrete specimen is reflected back as a tension wave at the concrete/buffer bar interface.The spalling in the concrete is detected by examining the profile of the transmitted pulse in the buffer bar.Even though the profile of the transmitted pulse recorded by the strain gages on the buffer bar may vary due to wave dispersion in such a viscoelastic buffer bar,a 3-D finite element analysis indicates that the wave dispersion correction is not necessary when the transmitted pulse is used to determine the spalling strength of the concrete specimen.The spalling strength is determined by using the records from the strain gages on the buffer bar on the basis of classic 1-D theory of characteristics.