C V R Murty

In a companion paper, new tapered configurations are proposed of slender RC structural walls with and without enlarged boundary elements at the wall-footing junction region. On the basis of identified parametric limits and the wall response in linear-elastic finite-element analyses, a stepwise seismic design procedure is proposed of tapered integrated wall-footing systems with soil or rock anchors at the bottom. This incorporates a capacity design of the plastic hinge region above the tapered portion and an elastic design of the tapered portion. The location of the region of seismic damage and energy dissipation in the wall is controlled by proportioning of the tapered wall-footing as per the new design procedure. © 2014 American Society of Civil Engineers.

The paper reviews seismic behaviour and performance of reinforced concrete (RC) deep vertical members, particularly bridge piers and structural walls. The provisions of the relevant Indian codes of practice, concerning shear strength and shear demand in these members, are reviewed in light of the provisions of international codes of practice. The deficiencies are identified in the seismic shear design philosophy, prescribed by Indian codes.

In multistoried RC wall-frame buildings, properly designed and detailed RC slender structural walls significantly improve earthquake resistance. In walls on isolated spread footings with marginal taper, severe stress concentration is observed at the wall-footing junction during earthquake shaking. In this paper, new tapered configurations are proposed in the bottom portion of walls with and without enlarged boundary elements. Analytical correlations are derived among salient structural and soil parameters of the tapered wall-footing. An extensive parametric study is carried out through linear-elastic finite-element analysis of an isolated wall-footing system under estimated actual vertical and lateral forces. Under the estimated forces, significant loss of contact is observed at the bottom of the wall-footing; thus, soil or rock anchors need to be provided to ensure stability of the wall-footings during strong shaking. Force flow from wall to footing improves significantly in the proposed integrated wall-footing system. In the wall, the region of the inelastic response and possible seismic damage is expected to occur above the tapered region and away from the footing level. Permissible parametric limits are also proposed through the observed stress-deformationresponse. © 2014 American Society of Civil Engineers.

Based on the review of seismic shear design provisions of Indian codes for reinforced concrete (RC) deep vertical members (i.e., bridge piers and structural walls) in a companion paper, basic provisions are identified for shear resistance of RC sections. Draft provisions are presented for the consideration of the relevant Indian design code committees on bridge and building. The best seismic design practices seem to suggest that these provisions will be beneficial for the seismic performance of deep RC vertical members.