Joseph Penzien

Seismically induced racking of tunnel linings

An analytical procedure is presented for evaluating the racking deformation of rectangular and circular tunnel linings caused by soil–structure interaction during a seismic event. The procedure, as applied to rectangular linings, is supplementary to that previously published by Penzien and Wu (Earthquake Engineering and Structural Dynamics, 1998; 27:283–300) for circular linings. Copyright

Stresses in linings of bored tunnels

An analytical procedure is presented for evaluating the stresses in linings of bored tunnels caused by kinematic soil–lining interaction. Three cases of plane–strain interaction are treated as produced by (1) relaxation of in situ soil stresses near a lining following its installation, (2) overburden pressure at the soil surface, and (3) two-dimensional free-field soil response normal to the lining axis as produced by an earthquake. The procedure is applied separately to a steel lining and a concrete lining for a site located at the lower end of Market Street in San Francisco through which a BART (Bay Area Rapid Transit) tunnel passes.

Evaluation of building separation distance required to prevent pounding during strong earthquakes

Presented herein is an analytical procedure for evaluating the separation distance required between two buildings to prevent pounding during strong earthquakes. The procedure is based on equivalent linearization of non-linear hysteretic behaviour and application of the well-known CQC method of weighting normal mode responses. The numerical results obtained are compared with corresponding results obtained using the well-known SRSS and ABS methods.

Stochastic response of offshore towers to random sea waves and strong motion earthquakes

Abstract Presented is a stochastic method of analysis of offshore towers subjected separately to random sea waves and to strong motion earthquakes. The Pierson-Moskowitz wave height spectrum is used along with linear wave theory to define a stationary random sea state as caused by wind generated surface waves. A zero mean ergodic Gaussian process of finite duration is used to characterize horizontal ground acceleration caused by strong motion earthquakes. For each type of loading, full fluid structure interaction effects are included in stochastic analysis. Numerical results for 4 representative deep water towers having heights of 475, 675, 875 and 1,075 feet are presented. Particular emphasis is placed on the maximum or extreme values of total transverse shear and total overturning moment versus elevation above the base of each tower. The results of the earthquake analysis are compared with corresponding design code values and the role of ductility is briefly discussed.

Comparison of treatments of non-linear drag forces acting on fixed offshore platforms

A single-degree of freedom system model of a fixed offshore platform is subjected to hydrodynamic forces. Solutions are obtained using three different forms of representing the drag forces: non-linear and coupled to the structure responses; non-linear and uncoupled; and the standard linearized form. For a harmonic sea state, a solution of the non-linear coupled case was obtained through a step-by-step integration procedure. Solution of the non-linear uncoupled case was obtained by decomposing the drag forces into harmonics and then using superposition to obtain total response. Solution of the linearized case was obtained in the normal way which included iterations in the solution to arrive at a consistent linearized model of the drag forces. Response time histories were also obtained for a simulated random sea state. From these, response statistics were computed and tests were performed on the sample extreme values to determine their fitness to the Gumbel Type I probability distribution.

Three-Dimensional Stochastic Response of Offshore Towers to Wave Forces

A theory has been developed to calculate the dynamic response of offshore towers to random wave forces. Vibrations are considered simultaneoulsy in the orthogonal horizontal directions and for rotations about a vertical axis. A lumped mass model of the structure is used in the dynamic analysis. Numerical results for seven deep water towers having heights of 475, 675, 875, and 1,075 feet, are presented. These results include standard deviations and mean peak values for displacements, rotations, shear forces and twisting and bending moments. They show that the directional spread of the waves normally has little effect on the rotational response, and that the effect of the rotational response on the overall structural response is small.

Soil-Structure Interaction Analysis Using Multiple Input Motions

A soil-structure interaction analysis procedure using hybrid modelling is presented which takes into account the effects of wave scattering, spatial variations of seismic input motions, and the nonlinear response of soils. The effectiveness and efficiency of the procedure are investigated through correlation studies using field-model test results.