The paper brings up to date and amplifies earlier work on earthquake-induced ground displacements using near-field strong-motion records, improved processing procedures and a homogenizing treatment of the seismological parameters. A review of upper bound limits to seismic displacements is given and a predictive procedure is examined that allows the probabilistic assessment of the likelihood of exceedance of predicted displacements to be made in the near field of earthquakes in the magnitude range 6.6 to 7.3. Using a considerable number of unscaled ground motions obtained at source distances of less than half of the source dimensions, graphs and formulae are derived that allow the assessment of permanent displacements of foundations and slopes as a function of the critical acceleration ratio.

Earthquake‐induced ground displacements

Field and laboratory observations of seismic settlements of shallow foundations on granular soils that are not attributable to changes in density or liquefaction are explained in terms of seismic degradation of bearing capacity. Limit analysis using a Coulomb‐type mechanism including inertial forces in the soil and on the footing gives expressions for seismic bearing capacity factors that are directly related to their static counterparts. Comparison of the two depicts clearly the rapid deterioration of the overall foundation capacity with increasing acceleration. Such periodic inertial fluidization causes finite settlements that are possible even in moderate earthquakes. Reduction in foundation capacity is due to both the seismic degradation of soil strength and the lateral inertial forces transmitted by shear to the foundation through the structure and any surcharge. A straightforward sliding‐block procedure with examples is also presented for computing these settlements due to loss of bearing capacity f...

Seismic bearing capacity and settlements of foundations

Seismic passive resistance by pseudo-dynamic method

Abstract We describe Paratoceras tedfordi, a new species of Protoceratidae from early Miocene amber-bearing sands near Simojovel, Chiapas, southern Mexico. The holotypic cranium weakly expresses maxillary plates, supraorbital rugosities, and a median occipital projection as in the type of Paratoceras wardi, and is interpreted as a female. Its short facial region, elongate premolars, and brachydont molars place it among the Protoceratinae, not Synthetoceratinae. We also describe new cranial and the first postcranial material of Prosynthetoceras texanus from Alum Bluff and Thomas Farm sites in Florida. Incorporating data from these new specimens, we consider highlights of protoceratid adaptive morphology including their elaborate male ossicones, tapirlike proboscis, brachydont to mesodont dentition, and limb features and proportions. We suggest that progressive protoceratids may be seen as ecological analogues of the Bushbuck of South Africa, a forest-adapted browser. Each of the three groups of horned Protoceratidae speciated allopatrically along latitudinal lines, with the northern branch becoming extinct earlier than its southern sister. Their greater proclivity toward survival in tropical latitudes explains the importance of Protoceratidae in the Gulf Coastal Plain during the Miocene, and evident higher abundance of Paratoceras in Central America.

Chapter 14: New Evidence of Miocene Protoceratidae Including a New Species from Chiapas, Mexico

An alternative to the Mononobe–Okabe equations for seismic earth pressures

First, the paper shows that in order to use the quasi-static Mononobe-Okabe analysis for the prediction of earthquake dynamic forces on a gravity retaining wall, wall inertia effects must be included. Second, a design procedure is developed in which the designer chooses an acceptable level of wall displacement: he then computes the design wall weight which will restrict displacement in an earthquake to the predetermined level. Wall inertia effects are shown to be of the same order as the dynamic soil thrust, and to be sensitive to vertical acceleration and to base and wall friction. Design recommendations are given which relate to proposed American provisions for seismic zoning.

Seismic Behavior of Gravity Retaining Walls

The results of a parametric study (based on a Mononobe-Okabe analysis) of passive earth pressure resistance of cohesionless soils under dynamic loading are presented. Since passive resistance decreases with increasing ground acceleration while the failure zone increases in size, retaining structures designed for static loading conditions may prove to be inadequate under seismic loading. The mathematical equivalence of the active and passive earth pressure problems is demonstrated and a number of ambiguities (surrounding the passive earth pressure problem) in the literature are resolved.

Passive Pressure During Seismic Loading

Seismic Design of Retaining Walls

An analytical model which will predict the full-range behavior of reinforced concrete beams and frames has been developed. The numerical solution is accomplished using existing stiffness methods of analysis modified to suit reinforced concrete behavior. The only necessary material properties are the concrete compressive strength and steel yield strength. The model serves as an adjustable analytic prototype to which actual large- and small-scale structures tested at Princeton and elsewhere have been compared. In general, agreement is good with successive concrete cracking, moment distribution, and hinge formation illustrated. The validity of very small-scale microconcrete models as an alternative to full-scale model tests and analytic analysis is also demonstrated.

Full-Range Analysis of Concrete Frames

Experimental and finite element techniques are used to study the effect of such factors as interface slippage on the elastic soil-structure interaction of long-span, flexible, elliptic culverts and underpasses. The two-dimensional analyses of both a deeply buried pipe under distributed loading and a shallow conduit under concentrated loading indicate that the soil can be the basic load-supporting component of the system, as has been observed earlier for circular pipes. The experimental work is possibly the first application of the combined holographic-interferometric and photoelastic approach to a practical civil engineering problem.

Rowland Richards

Papers

Seismic Behavior of Gravity Retaining Walls

Passive Pressure During Seismic Loading

Seismic Design of Retaining Walls

Full-Range Analysis of Concrete Frames

Stresses around flexible elliptic pipes