Month: February 2018

C++ Code

Calculation of pile end bearing capacity and skin friction using CPT data based on the approach of Bustamante and Gianeselli (1982) – C++ Code

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 As you all know one of the substantial advantages of Cone Penetration Test (CPT) is that the test provides a continuous profile of soil response. This is why CPT methods generally give superior predictions of axial pile capacity compared to most conventional methods (Robertson, 2015). Bustamante and Gianeselli (1982) proposed a CPT-based analysis procedure based on… Read More

Excel VBA (Macro)

Macro for calculating pile downdrag force based on Neutral Plane Method

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 Long-term consolidation, seismic dry sand and liquefaction-induced settlements of a soil deposit can impart significant amount of downward load to piles. This load, called downdrag or negative skin friction, is caused by the friction between the pile and the downward moving soil. In my previous post (click here), I explained how to calculate downdrag load… Read More

Excel VBA (Macro)

Macro for calculating pile downdrag force per AASHTO LRFD Bridge Design Manual

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 Long-term consolidation, seismic dry sand and liquefaction-induced settlements of a soil deposit can impart significant amount of downward load to piles. This load, called downdrag or negative skin friction, is caused by the friction between the pile and the downward moving soil. Per AASHTO LRFD Bridge Design guidelines, downdrag force should be determined as follows:… Read More

Geotechnical Topics

Determination of active seismic earth pressure on retaining structures

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 Common simplified approaches to calculate seismic active pressure are described below: 1. Semi-empirical Mononobe-Okabe Method The simplest method to approximate seismic active pressure is to use the approach of Mononobe-Okabe (M-O) which is originally based on Coulomb’s theory of static earth pressures. The method incorporates the following assumptions (Geraili and Sitar, 2013): The backfill soil… Read More

Geotechnical Topics

Simplified design methods – Seismic slope stability analysis

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 Current state of practice in North America to evaluate the performance of slopes during earthquake loading is to use one of the following approaches: 1.  Limit Equilibrium Approach This approach uses horizontal and vertical seismic coefficients ( and ) to estimate seismic loads and performs a traditional limit equilibrium analysis to evaluate factor of safety… Read More

OPENSEES TCL Code

Continuum model of a single ground improvement element under seismic loading – TCL file

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 OpenSees implementation of a single ground improvement (GI) element in a continuum soil domain is described here. The Unit Cell concept is adopted to develop the ground improvement layout. The unit cell consists of a single GI element located in the center of its equivalent influence zone. The model represents a GI element located on… Read More

OPENSEES TCL Code

Full-scale finite element continuum model of Meloland Road Overpass (Two-span Bridge) – TCL file

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 This Tcl code creates full-scale three-dimensional continuum model of Meloland Road Overpass (MRO) located in El-Centro, California. The code is generic and can be modified to simulate any two-span bridge with a structure similar to MRO.  Ground motion can be applied at the model base in two horizontal directions. Please read the article about base… Read More

C++ Code

Time history and spectral response analysis of a SDOF – C++ code

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 You can use this code to (i) compute spectral acceleration response spectrum of a given ground motion, and (ii) compute acceleration, velocity and displacement time histories for a single-degree-of-freedom (SDOF). Numerical integration is implemented by using Newmark-bata method. The code solves the motion equation for a SDOF represented by a mass and dashpot as shown… Read More