Influence of Loading Angle on the Performance of Registration Pin Connection in VectorBloc Modular Construction System

Z-Modular has recently introduced an innovative construction method known as the VectorBloc modular construction system. The VectorBloc connector plays an integral role in this system, and it is necessary to assess its performance across a range of structural scenarios. The registration pin is a critical component of this connector, designed for module lifting during the installation process. This paper highlights the outcomes of the experimental tests conducted on different iterations of the registration pin connections, totaling 36 connection specimens. Three parameters were considered: thickness of the lifting plate, the thread size (threads per inch—TPI) of the registration pin and the loading angle. Various failure modes were observed during these tests, including weld or shackle ruptures. However, thread stripping emerged as the most common one. The test results indicate that a thicker lifting plate and a smaller TPI value (coarser threads) on the registration pin threads enhance connection capacity (lifting). An increase in the loading angle, on the other hand, reduces the connection capacity. While several standards, such as ASME B1.1 [1], ISO/TR 16224 [2], and BS 3580 [3], offer equations for evaluating thread capacity at a zero-loading angle, there are no existing design equations for accurately determining the lifting capacity when the load is applied at an angle to the pin connection. This paper investigated the impact of the loading angle on thread resistance and, consequently, load-carrying capacity when various design parameters are changed.