Analysis and Monitoring of the Construction Process： Synchronous Cumulative Sliding Lifting of a High⁃Altitude Double⁃Layer Steel Truss Corridor

A certain hotel project has set up a high-altitude double-layer steel truss corridor between two towers， with a span of 69.5 m and a total mass of 3485 t， using Q420GJC box-section components. Due to site limitations （only a 20 m × 70 m working surface） and cost control for machinery， a steel column support platform assembly sliding technology was selected. The overall lifting was achieved after accumulating three sliding cycles. By analyzing the phased assembly sliding and overall lifting processes， and combined with construction process monitoring， the structural safety was ensured. The truss structure was divided into four sliding units， namely Unit 1， Unit 2， Unit 3， and Unit 4， and they were installed using the "cumulative sliding installation" method. A slip analysis model was established based on the slip process. Firstly， only the self-weight load was applied to extract the reaction force at each fulcrum， which was converted into frictional force and applied to the slip analysis model. The calculation results showed that the maximum vertical displacement of the truss during the sliding process was -4.8 mm， and the maximum stress ratio was 0.112. The strength and stiffness of the structure during the sliding process met the requirements. Based on the analysis results of the sliding process， the fulcrum reaction force and friction force were extracted and applied to the sliding beam analysis model. The results showed that the maximum vertical displacement occurred at the edge sliding beam， with a maximum vertical displacement of -7.3 mm. The maximum stress ratio of the supporting component was 0.789， and both the displacement and stress ratio of the sliding beam were below the limit. According to the analysis results， monitoring points were set up at locations with high stress and displacement during the sliding process of the truss and sliding beam. The monitoring results showed that the stress and displacement at each measuring point during the sliding process were lower than the calculated results.After sliding to the design position below， the synchronous lifting construction phase was carried out. This involved utilizing the surrounding tower structural columns to set up lifting brackets and install lifting equipment to serve as lifting points. Lower lifting points were established on the upper chord of the truss structure， which were then reinforced with stiffening members. After the suspension points were fine-tuned to level the structure， the formal lifting process commenced. The process was paused every 5 meters to adjust the structural alignment until it reached the design position.The lifting process analysis model and the lifting bracket analysis model were established based on the lifting process and structural layout. The results indicated that as long as the asynchronous lifting value was guaranteed not to exceed 25 mm during the lifting process， the impact of asynchronous effects on structural safety could be neglected. The maximum displacement of the structure occurred at the mid-span location， with a maximum vertical displacement of 20.8 mm. The lifting truss exhibited a maximum stress ratio of 0.269， while the stiffening members showed a maximum stress ratio of 0.723. The maximum vertical displacement and maximum stress ratio of the lifting brackets were -7.2 mm and 0.783， respectively. Both the strength and stiffness of the lifted structure and brackets met the specified requirements. According to the analysis results， monitoring points were set up at locations experiencing high stress and displacement on the truss and lifting brackets. The monitoring results showed that the stress and displacement at each measuring point during the lifting process were lower than the calculated values.