A numerical study on response factors for steel wall–frame systems

Abstract

A numerical investigation was undertaken to evaluate the response of dual structural systems that consisting of steel plate shear walls and moment-resisting frames. The primary objective of the study was to investigate the influence of elastic base shear distribution between the wall and the frame on the global system response. A total of 10 walls and 30 wall-frame systems, ranging from 3 to 15 stories, were selected for numerical assessment. These systems represent cases in which the elastic base shear resisted by the frame has a share of 10, 25, or 50% of the total base shear resisted by the dual system. The numerical study consisted of 1600 time history analyses employing three-dimensional finite elements. All 40 structures were separately analyzed for elastic and inelastic response by subjecting them to the selected suite of earthquake records. Interstory drifts, top story drift, base shears resisted by the wall, and the frame were collected during each analysis. Based on the analysis results, important response quantities, such as the strength reduction, the overstrength, and the displacement amplification factors, are evaluated herein. Results are presented in terms of displacement measures, such as the interstory drift ratio and the top story drift ratio. Analysis results revealed that the increase in the strength reduction factor with the amount of load share is insignificant. Furthermore, there is an inverse relationship between the ductility reduction and the overtsrength. Figure 5. Push-over like curves.As shown in Figure 5, the base shears at the structural yield level for the wall, the frame, and the wall-frame can be found from pushover-like curves. As mentioned above, a simple hand method was developed to predict these base shear values. The estimates from simple plastic analysis were correlated with the results of nonlinear time history analysis for this purpose. The simple plastic analysis for SPSWs proposed by Berman and Bruneau [18] can be extended to dual systems. For a wall with constant infill plate thickness, the base shear at the structural yield level (V w ) can be Figure 7. Relationship between elastic and inelastic displacements.The scatter in results is attributable to the variation in ground motion characteristics. When a structure is subjected to different ground motions, the maximum force versus maximum displacement relationship is not perfectly linear. Depending on the dominant frequency of the ground motion and the structural periods, results can deviate from linearity as shown in Figure 5. Observations from Figure 8 reveal that the TSDR values are more scattered than the ISDR values. Therefore, from this perspective, using interstory drift is better than using the top story drift as an index.After investigating the results for elastic behavior, the inelastic behavior was considered next. The R and C d relationship for inelastic displacements is also given in Figure 8. The trendlines fitted to the data points have a slope of 1.35 (R = 1.35C d ) and 1.39 (R = 1.39C d ) for normali...

Shaking‐table tests of a full‐scale single‐story masonry veneer wood‐frame structure

“…However, a prior study by Okail et al [10] on the out-of-plane performance of individual wall segments tested on a shaking table showed nail extraction capacity much higher than what was observed here. This difference can be attributed to the higher moisture content of the wood studs in the present study.…”

“…Tie connections can also be weakened by the cracking of masonry veneer due to differential foundation settlements. Okail et al [10] have shown that the cracking of bed joints of a veneer wall can have a significant influence on the distribution of the tie forces induced by earthquake motions. Choi and LaFave [9] have investigated the performance of corrugated sheet metal ties by subjecting them to cyclic axial and lateral shear forces.…”

“…This veneer failure was caused by complete nail extraction from the wood studs (See Figure 10). Based on the observations from the tests conducted earlier on individual wall segments [10] and the analytical studies conducted prior to the building tests [19], this mode of failure was not expected until much higher levels of ground shaking. The rest of the structure, in contrast, showed no signs of distress under this level of shaking.…”

“…However, little is known about the seismic performance of masonry veneer systems designed and constructed according to current code provisions. Recently, a number of studies [2,9,10] have been conducted to investigate the seismic behavior of masonry veneer on wood-framed backing systems. While these studies have provided useful information about the cyclic behavior of veneer anchors and the performance of isolated wall segments under dynamic loading, there is little knowledge of how a building system of this type will perform in an earthquake, particularly with respect to the influence of roof diaphragm-to-stud wall connection details, the boundary conditions of a veneer wall, and the system-level interaction between the wood structure and the masonry veneer.…”

“…In this project, wall assemblies that were representative of wall configurations found in typical one-story buildings were tested quasi-statically and on a shaking table under separate in-plane and out-of-plane loads [10]. In addition, two single-story building specimens with plan dimensions of about 6 m × 6 m (20 ft × 20 ft) were tested to failure on a shaking table.…”