# A Review on Design Considerations and Connection Techniques in Modular Composite Construction
## 3 Area of Research
### Connections in Modular Construction Scenario  
The evaluation of precast concrete connections within modular construction necessitates a qualitative analysis of diverse performance metrics tailored to the specific requirements of the modular systems. While the comparative data are derived from studies on various precast structural configurations, these evaluations have been adapted to align with their application in modular construction, where prefabricated units typically weigh between 10 and 15 tons and require efficient and reliable assembly techniques. To facilitate this analysis, the radar chart (Figure 13) provides a comparative framework, summarising key factors such as load transfer capacity, seismic performance, durability, cost, construction speed, ease of installation, and maintenance requirements. These scores are synthesised from experimental results, analytical findings, and literature studies detailed in Tables 4 and 5, offering valuable insights into the suitability of different connection methodologies for modular construction scenarios. \begin{table}
\begin{tabular}{p{85.4 pt} p{85.4 pt} p{85.4 pt} p{85.4 pt}} \hline \hline
**NDE Method** & **Evaluated Parameter** & **Connection Type** & **Inferences** \\ \hline Ultrasonic Guided Wave [26] & Bond Quality, Debonding Detection & Steel Concrete Composite & Effective for detecting steel bonding at early stages \\ \hline Acoustic Emission [83] & Grout Compaction, Crack Initiation & Sleeve Ground Connection & Real-time monitoring of crack propagation \\ \hline Ultrasonic Pulse & Grout Strength, Void Detection & Sleeve Ground Connection & Reliable for detecting voids and unbonded regions \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Summary of non-destructive evaluation methods for composite connections. Each performance metric was analysed and scored from 0 to 100, where 0 reflects the lowest performance, and 100 reflects the highest performance. The scoring methodology was predicated upon a comprehensive examination of experimental investigations, as well as comparative evaluations elucidated in the referenced Tables 4 and 5. For instance, Load Transfer Capacity signifies the capability of the connection to efficiently convey loads between modules, with elevated scores denoting superior performance. Seismic performance assesses the robustness of the connection in the face of seismic forces, with increased scores indicating enhanced resistance to seismic events. Durability evaluates the protracted performance and resilience against deterioration, with elevated scores reflecting more robust connections. Cost scrutinises the economic ramifications, with diminished costs yielding higher scores. Construction Speed measures the temporal efficiency of the connection's installation, with expedited installations receiving higher scores. Ease of Installation assesses the intricacy and exertion required for assembly, with less complex installations achieving higher scores. Maintenance Requirements evaluate the continuous upkeep necessities, with reduced maintenance demands resulting in higher scores. By standardising these performance metrics on a 0 to 100 scale, the radar chart visually delineates each connection technique's comparative strengths and weaknesses, thereby offering a lucid and succinct comparison for stakeholders engaged in the construction sector. The load transfer capacity is a critical determinant of connection performance, directly impacting structural stability and force transmission efficiency. Connections utilising cast  
Figure 13: Comparative evaluation of connection techniques across key performance factors in modular construction, with scores reflecting their relative performance. in situ and grouted couplers achieved the highest ratings owing to their provision of monolithic or near-monolithic behaviour, which facilitates effective stress distribution under both static and dynamic conditions.