基于高强高延性PE-ECC的钢筋混凝土板-柱节点抗冲切性能试验研究

EXPERIMENTAL STUDY ON PUNCHING SHEAR PERFORMANCE OF REINFORCED CONCRETE SLAB-COLUMN CONNECTIONS USING HIGH STRENGTH AND HIGH DUCTILITY PE-ECC

  • 摘要: 针对普通钢筋混凝土板-柱节点抗冲切性能相对较差的特点,基于国产PE纤维,研发了高强高延性水泥基复合材料(PE-ECC),提出在节点核心及柱周1~2倍板厚(h)区域采用PE-ECC替换混凝土的新型板-柱节点。以PE-ECC替换范围及板纵筋配筋率为试验变量,设计制作了6个新型板-柱节点和1个普通钢筋混凝土板-柱节点,并进行了冲切试验。试验表明:与普通钢筋混凝土板-柱节点相比,新型板-柱节点的抗冲切承载力和延性均得到有效的提高,配筋率相同的3个新型板-柱节点,随着ECC替换区域由1 h扩大至2 h,其抗冲切承载力分别提高了31.8%、49.2%、81.5%,延性系数分别提高了39.5%、65.4%、83.9%,表明其具有工程实用性;因PE-ECC替换范围及配筋率的不同,会发生沿柱边及沿PE-ECC与混凝土界面的冲切破坏;随着受拉纵筋配筋率的提高,板-柱节点开裂后的刚度和抗冲切承载力都有明显的提高,但延性有所降低,节点的破坏模式逐渐转向冲切破坏;采用包括中国规范在内的四种常用混凝土规范公式计算新型板-柱节点的抗冲切承载力时,计算值与试验值之间均存在不同程度的偏差。课题组将在后续研究中针对PE-ECC的合理替换范围及适宜的抗冲切承载力计算公式进行深入研究。

     

    Abstract: Aiming at the poor punching resistance of normal reinforced concrete slab-column connections, based on domestic PE fibers, a high-strength, high-ductility Engineered Cementitious Composite (PE-ECC) was developed. Moreover, a new type of slab-column connections with the concrete replaced by the domestic PE-ECC in the core and in the area of 1-2 times the slab thickness around the columns is proposed. Six new type slab-column connections and normal ones are designed and fabricated for the punching shear test. The experimental results show that the punching shear capacity and ductility of new slab-column connections are effectively improved, compared with those of normal slab-column connections. With the expansion of the ECC replacement range from 1 h to 2 h, the ultimate shear capacity of the new three slab-column connections with the same reinforcement ratio has increased by 31.8%, 49.2%, and 81.5%, respectively. At the same time, the ductility coefficients have also increased by 39.5%, 65.4%, and 83.9%, which verify the practicality. Due to the replacement range of ECC and reinforcement ratios, punching failure occurs along the edge of the column and along the ECC-concrete interface. With the increase in reinforcement ratio, the post-cracking stiffness and ultimate bearing capacity of slab-column connections are significantly improved, but the ductility is reduced, and the failure mode is gradually shifted to punching failure. In addition, four current concrete codes, including the Chinese Code, are used to calculate the punching shear capacity of the new slab-column connections and to compare them with the test results. The research results show that there exist different degrees of deviation between the calculated values and test values. The research group will conduct in-depth research on the reasonable replacement range of PE-ECC and the appropriate calculation formula for shear resistance in subsequent studies.

     

/

返回文章
返回