Author: Amin

MATLAB

Modified Newmark Sliding Block (Deformable Sliding Block) For Estimating Seismic Lateral Movement of Slopes

Posted on
 

 Introduction Practitioners often perform Newmark Sliding Block analyses to predict permanent lateral displacements of slopes under earthquake loading. In this method, sliding of a rigid block of soil mass is computed by double integration of acceleration over the length of time during which the yield acceleration (i.e., friction coefficient) is exceeded. For better illustration purposes,… Read More

Geotechnical Topics

A Design Conflict in Section 11.8.3-item 1 of ASCE 7-10&16 (Determination of Seismic Earth Pressures on Basement and Retaining Walls)

Posted on
 

 The maximum considered earthquake geometric mean (MCEG) peak ground acceleration (PGAM) is commonly used in the USA to perform geotechnical evaluations including liquefaction, lateral spread, and pseudo-static slope stability analyses. However, to determine seismic earth pressures on basement and retaining walls, ASCE 7-10 and 7-16 Section 11.8.3 – item 1 allows using “Design” Earthquake PGA… Read More

Geotechnical Topics

An Alternative Approach To Determine Static and Seismic Passive Pressure

Posted on
 

 Introduction The current state of practice  adopts Rankine/Coulomb theory to estimate static passive pressure and Mononobe-Okabe (M-O) method to determine seismic passive pressure. As you know, each of these approaches were formulated based on some assumptions that may not apply to all of our daily engineering problems. For instance, the M-O method was originally developed… Read More

OPENSEES TCL Code

Beam on Nonlinear Winkler Foundation (BNWF) Model for Soil-Wall/Soil-Pile Interaction Analysis – TCL File

Posted on
 

 The current engineering practice adopts the concept of beam on a nonlinear Winkler foundation (BNWF) in order to perform displacement-based analysis on piles, cantilever walls, and bulkhead systems. This post provides an OpenSees TCL file to develop the BNWF model of a beam supported on a series of nonlinear springs. Similar to other OpenSees TCL… Read More

Geotechnical Topics

Introduction to Probabilistic Seismic Hazard Analysis (PSHA)

Posted on
 

 Unlike Deterministic Seismic Hazard Analysis (DSHA), Probabilistic Seismic Hazard Analysis (PSHA) allows uncertainties in the size, magnitude, location, site condition, and rate of recurrence of earthquakes to be considered in the evaluation of seismic hazards for a particular project site. This post uses the presentations of Professor Kevin Franke from Brigham Young University and Professor Jack… Read More

OPENSEES TCL Code

Single Pile Pushover Analysis Using Continuum Modeling Method – TCL File

Posted on
 

 This Tcl code creates full-scale three-dimensional continuum model of single pile embedded in a layered soil profile. Soil-pile interaction including formation of gap and slippage was simulated by using the BeamContact3D element. The program is capable of performing a lateral pushover analysis on a single pile. The contact elements at the interface of soil and pile… Read More

Excel VBA (Macro)

Macro for computation of acceleration, velocity and displacement response spectra

Posted on
 

 The VBA macro implemented in the enclosed spreadsheet calculates: (1) the time histories of velocity and displacement of the input acceleration time history, and (2) the spectral responses of acceleration (Sa), velocity (Sv), and displacement (Sd). The code is formulated based on the Newmark-bata numerical integration method. Note that C++ format of this code is… Read More

Geotechnical Topics

Verification vs. Validation in Numerical Modeling

Posted on
 

 Verification and validation are the essential procedures required to assess accuracy and credibility of numerical analyses. The terms “verification” and “validation”  are often used interchangeably in the current engineering practice. However, the two procedures have entirely different meanings and applications. The differences are outlined below: Verification is meant to identify and remove programming errors in a… Read More

Geotechnical Topics

Advantages of performing strain-based analysis for pile design

Posted on
 

 Per the current state of practice, a pile design is typically completed by checking the following design items: Static settlement which includes elastic compression of pile, immediate and consolidation settlements of soil; Structural and geotechnical bearing capacity of pile in static and seismic conditions; Seismic settlement under downdrag forces induced by the surrounding soil during… Read More