Response Spectrum Method Of Analysis – with simplified examples

Response Spectrum Method of Analysis

Response Spectrum Method Of Analysis (Click here for Response SA in Staad Pro ) Introduction Response spectrum method is favoured by earthquake engineering community because of:  It provides a technique for performing an equivalent static lateral load analysis.  It allows a clear understanding of the contributions of different modes of vibration.  It offers a simplified … Read more

Shape functions for different elements used in finite element analysis

Shape functions or interpolation functions are functions used to represent behaviour of a field variable within an element. In finite element analysis we deal with different elements. The elements can be linear, quadratic, 8- noded, 9-noded etc. The shape function for these elements is required to be determined to draw a relationship between the nodal … Read more

Fundamentals of Prestressed Concrete Bridge (with solved example)


Fundamentals of Prestressed Concrete Bridge (with solved example) Introduction: In prestressed concrete, a prestress force is applied to a concrete member and this induces an axial compression that counteracts all, or part of, the tensile stresses set up in the member by applied loading.  In the field of bridge engineering, the introduction of prestressed concrete … Read more

Classical Rayleigh Ritz Method


Classical Rayleigh Ritz Method Introduction: Classical Rayleigh Ritz Method is named after Walther Ritz and Lord Rayleigh and is widely used. Classical Rayleigh Ritz Method is a method of finding displacements at various nodes based on the theorem of minimum potential energy. Departure from classical Rayleigh Ritz Method leads to FEM. The two departures are: … Read more

Response Spectrum Analysis in STAAD explanation Video

Response Spectrum Analysis in STAAD explanation Video Methodology The design lateral shear force at each floor in each mode is computed by STAAD in accordance with the IS: 1893 (Part 1) -2002 (equation and Qik = Ak*fik*Pk*Wi STAAD utilizes the following procedure to generate the lateral seismic loads. User provides the value for … Read more

Principle of Virtual Work and Minimum Potential Energy (P.E.)


Principle of Virtual Work and Minimum Potential Energy (P.E.)   Introduction: The Total Potential Energy is nothing but the energy due to Strain Energy (internal work done) and Work potential of a force (external work done).   Theorem of P.E.: Of all the displacements satisfying given Boundary conditions and Equilibrium conditions, the actual displacement is … Read more

Shape Functions or Interpolation Functions

Simple Element Shapes

Shape Functions or Interpolation Functions In FEA we discretize the solution region into finite elements. To conduct the analysis we assume a displacement model to approximately indicate the variations of the displacement within the element. The polynomial chosen to interpolate the field variables over the element are called shape functions. Denoted by[N], they establish the … Read more


Isolation reduced the damages caused during an earthquake

SOFT STOREY EFFECT In shaking a building, an earthquake ground motion will search for every structural weakness. These weaknesses are usually created by sharp changes in stiffness, strength and/or ductility, and the effects of these weaknesses are accentuated by poor distribution of reactive masses. Severe structural damage suffered by several modern buildings during recent earthquakes … Read more

Types of Concrete Mixes

concrete mixes

Nominal Mixes In the past the specifications for concrete prescribed the proportions of cement, fine and coarse aggregates. These mixes of fixed cement-aggregate ratio which ensures adequate strength are termed nominal mixes. These offer simplicity and under normal circumstances, have a margin of strength above that specified. However, due to the variability of mix ingredients … Read more