The application of reinforced concrete modular integrated construction (MiC) has gained popularity in Hong Kong, but challenges still exist in the temporary tying of side walls during composite wall construction. This paper presents an innovative inner tie system for composite walls, applied in a MiC project in Hong Kong. The system’s components are installed on the side walls of precast modules in the factory without the need to penetrate through the walls. After transport to the site, by rotating the loop on-site to engage the hook, the tying effect is achieved during on-site concrete pouring between the interstitial space of two modules. This system eliminates the use of tie bolts that penetrate precast side walls, allowing for comprehensive interior fitting-out in the factory and minimizing disruptions to internal decoration during on-site construction. The paper presents the system’s mechanism, nonlinear Finite Element Analysis (FEA) simulation, section size optimization, and validation through tensile and punching shear tests. Furthermore, an instrumented mockup module assembly was carried out, and the system was eventually applied in a real MiC project. The system can effectively control the horizontal deformation of MiC module side walls within a limit. Compared to current existing tying methods, this system offers easy installation, load-bearing reliability, adaptability to certain construction errors, savings on manpower and construction time, and also a decrease in construction waste and carbon emission. It will provide a valuable reference for future MiC projects.

Due to outstanding mechanical properties and economic advantages, high-strength steel, especially S690, is used more frequently in construction projects. Unlike traditional steel, working with S690 steel requires meticulous control over welding parameters to ensure quality and safety during construction. For construction projects in Hong Kong, bolted connections are commonly used for assembling S690 members on-site, as field welding has not been verified. To evaluate the viability and refine the methodology of field welding, a series of tests was conducted. This investigation began with tensile tests of butt welds on steel plates, followed by evaluations of splice welds for H-section steel components. This research assessed several critical parameters influencing weld integrity, including heat input, joint details, thermal treatment processes, and the implementation of wind shielding. The work was conducted to enhance both the quality and productivity of field welding for S690 steel, thereby supporting progress for construction methodologies.

Steel platforms carrying construction traffic are subjected to repeated moving loads, while their structural response is commonly assessed through periodic inspection rather than continuous measurement. This study presents an Internet of Things (IoT)-enabled framework for monitoring the operational strain response of a sloped steel platform subjected to repeated haul-truck movements. Fifteen vibrating wire strain gauges (VWSGs) were installed on selected rafters, longitudinal members, columns, and diagonal braces. Time-stamped strain measurements were transmitted through a TH-RTU-C IoT gateway and a 4G network to a cloud-based monitoring platform and linked to a sensor-driven digital shadow. An event-preserving processing framework was applied to separate slowly varying strain components from truck-induced transient strain increments and to identify candidate loading events from temporally coordinated multi-sensor responses. A time-stamped field photograph independently documented a reference truck event. Complete-duration event-level distributions showed a strongly nonuniform but recurring spatial response pattern, with these three channels consistently exhibiting the largest local strain increments. The documented event provided a physical reference for interpreting the broader candidate-event distributions observed during routine operation. The sensor-driven digital shadow integrates platform geometry, VWSG locations, near-real-time strain histories, historical event review, and local strain-demand indicators. The interface allows monitored responses to be compared with adopted engineering strain limits and visualized using Normal, Attention, and Critical operational states. The results show that event-level statistical characterization and IoT data transmission can establish operational strain-response envelopes, identify governing monitored locations, and convert continuous strain measurements into operationally interpretable information for steel structures.

High-strength S690 steel is becoming increasingly popular in Hong Kong because of its numerous advantages in terms of mechanical properties and cost-effectiveness. Compared to normal-strength steel, the welding parameters such as preheat temperature, inter-pass temperature, and heat input energy of high-strength S690 steel should be controlled more strictly; additional post-weld heat treatment should be carried out for hydrogen diffusion in some situations. These strict requirements pose challenges to welding operations at construction sites. In Hong Kong, all field connections of high-strength S690 steel components are made using bolted connections, and there are currently no precedents for welded connections on site. To verify the reliability of on-site welding and optimize the welding process to facilitate operation, on-site welding tests of high-strength S690 steel with various welding procedures were conducted. These welding tests were first performed on the steel plates, followed by tests on the H-section steel components, to examine the mechanical reliability of the welding connections under tension and compression. The effects of heat input energy, welding joints, post-weld heat treatment, and wind blocking measures on welding quality and welding efficiency were studied.