Shear and Flexural Stiffnesses of Reinforced Concrete Shear Walls Subjected to Cyclic Loading

Abstract

Seismic analyses of concrete structures under maximum-considered earthquakes require the use of reduced stiffness accounting for cracks and degraded materials. Structural walls, different to other flexural dominated components, are sensitive to both shear and flexural stiffness degradations. Adoption of the gross shear stiffness for walls in seismic analysis prevails particularly for the design codes in the US. Yet available experimental results indicate that this could overstate the shear stiffness by more than double, which would hamper the actual predictions of building periods and shear load distributions among columns and walls. In addition, the deformation capacity could be drastically understated if the stipulated constant ductility capacity is adopted. This paper reviews the available simplified shear and flexural models, which stem from classical mechanics, empirical formulations and/or parametric studies, suitable for structural walls at the state-of-the-art. Reviews on the recommended flexural and shear stiffnesses by prominent design codes such as ACI318-11, Eurocode 8 and CSA are included. A database comprised of walls subjected to reverse-cyclic loads is formed to evaluate the performance of each model. It is found that there exist classical models that could outweigh overconservative codified values with comparable simplicity for practical uses.

Simplified seismic assessment of buildings using non-uniform Timoshenko beam model in low-to-moderate seismicity regions

“…ACI318-11 (cl.8.8.2), a stiffness reduction factor of 0.5 applying to all elastic sectional properties is presumed herein, whereby: (5) in which β i denotes the period lengthening effect when the RC elements crack under the MCE event. The above value is consistent with findings by different researchers determined from RC wall panel cyclic tests [58], full frame numerical modeling (β i = 1.4 from Su et al [59,60]) or shake table tests for various building types when concrete cracks notably: e.g. high-rise shear wall buildings above a transfer frame (β i = 1.24 from Huang et al [61]; β i ≥ 1.3 from Ye et al [62]; first mode averaged β i along X and Y direction = 1.2 to 1.7 after major to super-major earthquake by Li et al [63]) and in-filled RC frame buildings (e.g.…”

A review on precast structural concrete walls and connections

“…Related with the previous topic, the different failure modes of walls under lateral loads are: sliding shear failure; flexure failure; diagonal tension failure; diagonal compression failure and hinge sliding failure (Figure 10).

Figure 10.Failure mode of structural walls: (a) sliding failure; (b) flexure failure; (c) diagonal tension failure; (d) diagonal compression failure; (e) hinge sliding failure (Tang and Su, 2014).

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Numerical analysis of lightweight concrete wall panels having a variation of dimensions and openings that were subjected to static lateral loads

“…Stiffness is dependent on structural configuration, dimension, member behavior, and material properties [24]. Stiffness (K) performs the load (F) to deformation (δ) ratio [25], as described in Equation ( 3):…”