# A Review on Design Considerations and Connection Techniques in Modular Composite Construction
## 3 Area of Research
### Experimental Studies on Connections  
Researchers have undertaken experimental investigations of various connection types, including grouted sleeve couplers, metal ducts, and steel plate bolted connections, to evaluate their mechanical capabilities when subjected to tensile and compressive forces. These assessments frequently incorporated large-scale experiments to analyse the strength and deformability of precast assemblies with grouted coupler connections and bolted connections and compared them with cast in situ joints. Tables 4 and 5 summarise the recent studies reported in the literature on dry and wet connections in precast structures and the main parameters studied in each research. Most of these investigations have concentrated on parameters including load-carrying capacity, ductility, stiffness, and seismic performance, which are essential for assessing the appropriateness of connections in modular construction. This underscores the significance of lateral and seismic performance as pivotal focal points in these studies, thereby indicating a necessity to delve deeper into these dimensions. A comprehensive chart that compares the qualitative findings of these investigations is provided in the following section, 'Connections in Modular Construction Scenario', to facilitate a more precise comparison of various connection methodologies in modular construction. \begin{table}
\begin{tabular}{l l l l} \hline \hline
**Year** & **Author** & **Prefabricated Structure** & **Parameters Studied** \\ \hline
2024 & [PERSON] [20] & Precast Wall Panel & Cyclic test on the horizontal connection of wall \\  & & & panels using friction bolts \\ \hline
2024 & [PERSON] et al. [62] & Precast Column & Lateral cyclic tests on precast column with \\  & & embedded plate and bolted connection \\ \hline
2024 & [PERSON] et al. [63] & Composite Precast Floor & Bending tests on high-strength bolts connecting \\  & & and Modular Steel Beam & precast floors and steel channel \\ \hline
2023 & [PERSON] et al. [64] & Precast Wall Panel & Lateral Cyclic Test on precast wall panel with \\  & & bolted connection \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Summary of investigations on dry connections in precast structures. Figure 11: Hybrid connection systems [61]. Figure 12 illustrates a comprehensive comparison of ultimate load and ductility across various structures, based on results reported in experimental studies. Peak load refers to the maximum load a structure can withstand before failure. In contrast, ductility is quantified as the ratio of ultimate deformation to yield deformation, reflecting a structure's ability to sustain displacement without brittle failure while maintaining structural integrity. This comparison encompasses various structural configurations, including bridge pier [77; 78], shear wall [57], column-to-the-foundation [79], beam-column joint [80], and column-to-column [81], which are assessed through various connection types: cast-in-place joint, grouted coupler joint, and steel plate and bolt joint. For example, the bridge pier utilising a grouted coupler joint demonstrates a maximum load of 163 kN and ductility of 5.85. In comparison, the cast-in-place joint reveals a lower maximum load of 143 kN yet a consid