Pushover Analysis on the Seismic Performance of RC Column-Staggered Truss Structure

Stagger truss structure system was derived from the middle of 1960s, with the advantages of open space, free layout, light weight, and convenient construction. The internal force of the frame column in stagger truss system is generally small because of the good overall mechanical performance and light weight, so the design of the steel column in the structure is usually controlled by the slenderness ratio. Construction Technology Co., Ltd. designed an RC column-staggered truss structure by replacing the conventional steel columns with precast RC columns. The application of the precast RC columns reduces the cost of the structure without reducing the quality and the convenient construction. A finite element model of a 9-story RC column-staggered truss structure in an area of 7-degree (0.1g) seismic fortification intensity was established by MSC. MARC software based on a practical project and the pushover analysis was conducted. According to the performance point of the structure, the seismic performance of the structure was analyzed in terms of the story drift, inter-story drift ratio, and member yielding sequence. Three models of removing partial diagonal web members were established based on the original model, and the failure effect of partial diagonal web members on seismic performance was analyzed.
The results are as follows:1) The maximum inter-story drift ratio of the RC column-staggered truss structure under the action of frequent earthquakes and rare earthquakes is far less than the limit value of the Specification for Design of Staggered Steel Truss Framing Systems (JGJ/T 329-2015). The maximum inter-story drift ratio appeared at the third and second floors. 2) The first yield diagonal web appeared in the of the middle and lower part of the stagger truss near the outside. With the increase of the seismic action, the diagonal web of the staggered truss on the inside also gradually yielded. 3) The structural capacity curves of the structures with diagonal web failures are basically the same as those of the original structures. With the increase of seismic fortitution level, the difference of peak displacement decreases from 8% to 3%. 4) The structural capacity curve does not decrease significantly with the failure of the partial diagonal web. The maximum inter-story drift ratio of the structure with partial diagonal web removed respectively increased by 11.9% and 32.7% under frequent earthquakes and rare earthquakes. The structure with partial diagonal web removed can still meet the design requirements of Specification for Design of Staggered Steel Truss Framing Systems (JGJ/T 329-2015). 5) There are 2-4 more members yielding in the structure with partial diagonal web removed, but the overall structure is still in an elastic state. the RC column-staggered truss structure has the characteristics of high rigidity and good seismic performance, meeting the seismic performance requirements of "no damage under frequent earthquake, no unrepairable damage under design-based earthquake, and no collapse under rare earthquake". The structures without partial diagonal web members show inferior seismic performance than the original one, but they can still meet the design requirements.