Field Monitoring Analysis and Welding Sequence Optimization of an Inclined-Column Dense-Beam Exterior Frame in a Super High-Rise Steel Structure

The exterior frame of super-high-rise steel structures with inclined columns and dense beams contains numerous welded joints and complex constraints, making field welding prone to residual stress and cumulative displacement. Taking the 19th erection segment of the Tianjin China Overseas City Plaza main tower as an example, this study monitored welding-induced stress and column-top displacement using vibrating-wire strain gauges and BeiDou GNSS, and established a finite element model based on the equivalent indirect action method to evaluate different welding sequences. The results show that stresses near welds evolve in stages during lower-flange, web, and upper-flange welding. Adjacent welding causes limited disturbance after the completed joint has stabilized, whereas lower-layer welding can induce secondary shrinkage in upper-layer welded regions. The simulated residual stresses and column-top offsets show reasonable agreement with the monitoring results in terms of overall magnitude and distribution trend, with mean values 2.50% and 6.22% lower than the measurements, respectively. Welding sequence significantly influences deformation. Horizontal grouped skip welding improves construction efficiency by about 30%, and vertical reverse welding further reduces the mean column-top offset by 53.31% and controls the maximum column-top offset within the project-specific limit. Therefore, under the studied structural configuration and construction conditions, the combined sequence of horizontal grouped skip welding and vertical reverse welding is recommended as a practical welding-sequence scheme.