Introduction

Earthquake engineering has advanced sufficiently in recent years, resulting in well-detailed, newly designed structures usually exhibiting adequate strength, stiffness and ductility to withstand severe earthquake ground motion. Nevertheless, the vast majority of the existing built infrastructure was constructed many years ago, when engineering expertise was not at today’s level of knowledge, and the safety regulations were less stringent. Consequently, in the structures designed according to older codes the focus had been placed exclusively on the vertical gravity forces, with little or no consideration for the lateral resistance system. Moreover, even if seismic loads have been explicitly considered, it is most likely that these structures do no longer meet the constantly updated regulations, since the rapid progress in the field of earthquake engineering during the last two or three decades has radically altered the design philosophy and standards worldwide.

As a result, the vast majority of the existing buildings exhibit significant deficiencies (reduced resistance to seismic loads, relatively small stiffness or ductility, soft storeys – short columns) that render them vulnerable in seismic events of high intensity, and require structural upgrading and retrofit.

Course Objectives

The purpose of the course is to introduce the students to the practical aspects of seismic assessment and retrofitting of existing reinforced concrete buildings, while also providing them with the opportunity to work on projects using some of the most advanced software available in this field. Upon completion, the participants will have gained significant knowledge on all the different methods for strengthening a structure that will allow them to evaluate and understand the available alternative solutions in different strengthening projects. The course will provide in-depth insight both:

• on the construction level; all the basic interventions techniques will be presented and different construction aspects will be explained, and
• on the design level; guidelines in the strategy of interventions and the selection of the appropriate interventions’ method will be provided

Within this context many real case studies will be presented, and it will be explained why in each case a specific retrofit scheme was preferred over other alternatives. Furthermore, with the use of SeismoStruct and SeismoBuild, two software packages specialised in the analysis, assessment and strengthening of existing structures, the students will learn how to carry out the full assessment and strengthening procedures of existing structures, from the structural modelling, through to the analysis and the checks according to the selected Codes (ASCE 41-23 and Eurocode 8 Part-3).

Introduction

Earthquake engineering has advanced sufficiently in recent years, resulting in well-detailed, newly designed structures usually exhibiting adequate strength, stiffness and ductility to withstand severe earthquake ground motion. Nevertheless, the vast majority of the existing built infrastructure was constructed many years ago, when engineering expertise was not at today’s level of knowledge, and the safety regulations were less stringent. Consequently, in structures designed according to older codes the focus had been placed exclusively on the vertical gravity forces, with little or no consideration for the lateral resistance system. Moreover, even if seismic loads have been explicitly considered, it is most likely that these structures do no longer meet the constantly updated regulations, since the rapid progress in the field of earthquake engineering during the last two or three decades has radically altered the design philosophy and standards worldwide.

As a result, the vast majority of the existing buildings exhibit significant deficiencies (reduced resistance to seismic loads, relatively small stiffness or ductility, soft storeys – short columns) that render them vulnerable in seismic events of high intensity, and require structural upgrading and retrofit.

Course Objectives

The purpose of the course is to introduce the students to the practical aspects of seismic assessment and retrofitting of existing reinforced concrete buildings, and at the same time to give them the opportunity to work on projects using some of the most advanced software available in this field. Upon completion, the participants will have gained significant knowledge on all the different methods for strengthening a structure that will allow them to evaluate and understand the available alternative solutions in different strengthening projects. The course will provide in-depth insight both:

• on the construction level; all the basic intervention techniques will be presented and different construction aspects will be explained, and
• on the design level; guidelines in the strategy of interventions and the selection of the appropriate interventions’ method will be provided

Within this context many real case studies will be presented, and it will be explained why in each case a specific retrofit scheme was preferred over other alternatives. Furthermore, with the use of SeismoBuild and SeismoStruct , two software packages specialised in the analysis, assessment and strengthening of existing structures, the students will learn how to carry out the full assessment and strengthening procedures of existing structures, from the structural modelling, through to the analysis and the checks according to the selected Codes (ASCE 41-23 and Eurocode 8 Part-3).

SeismoBuild is an innovative Finite Element package wholly and exclusively dedicated to seismic assessment and strengthening of reinforced concrete structures that is targeted to the design office. The program is capable of fully carrying out the Code defined assessment methodologies from the structural modelling through to the required analyses and the corresponding member checks. Linear Static Analysis, Linear Dynamic Analysis, Nonlinear Static Analysis and Nonlinear Dynamic Analysis is available with easy generation of spectrum compatible artificial or synthetic accelerograms. Currently six Codes are supported (Eurocodes along with the majority of the available National Annexes, American Code for Seismic Evaluation and Retrofit of Existing Buildings ASCE, Italian National Seismic Code NTC-18, Greek Seismic Interventions Code KANEPE and Turkish Seismic Evaluation Building Code TBDY). Both metric and imperial units, as well as European and US reinforcing bars types are supported.

FRP Designer is included in the installation since 2023 version of the program.

Some of the more important features of SeismoBuild are summarised in what follows:

• Completely visual interface. No input or configuration files, programming scripts or any other time-consuming and complex text editing requirements.
• With the Building Modeller the user can create real regular or irregular 3D reinforced concrete models within minutes.
• Easy CAD-based input; the floor’s plan view can be used as background.
• Predefined built-in cross-sections for both existing and strengthened (jacketed) members (rectangular, L-shaped, T-shaped, circular, shear walls, normal or inverted T-beams).
• More efficient way to introduce the jacketed sections.
• New 3-sided, 2-sided and 1-sided jacketed sections are available.
• Significantly faster analyses with the new parallel processing capabilities and a new sparse/profile solver.
• Infills and steel braces implemented in the Building Modeller.
• Easy modelling of strengthening with Fibre-Reinforced Polymers (FRP) wraps; a large library of existing FRP materials is available.
• Easy modelling of inclined beams and slabs.
• Automatic column subdivision to model short columns.
• Individual footings, Strip footings and Connecting beams are available for the modelling of foundation.
• Ability to print tables with all the model members and their properties.
• Straightforward definition of code-based parameters.
• Simple input of limit states, building performance levels, earthquake hazard levels and knowledge levels.
• Easy definition of the parameters needed for the nonlinear analysis, with a range of predefined settings schemes and detailed guidelines with suggestions by the program.
• Large library of nonlinear models for concrete and steel materials.
• Fibre-based inelastic and elastic frame elements.
• Distributed plasticity models to accurately model the distribution of inelasticity along the entire height of large walls.
• Eigenvalue, Linear Static, Linear Dynamic, Nonlinear Static and Nonlinear Dynamic analyses supported.
• User defined accelerograms may be imported in nonlinear dynamic analysis.
• AVI movie files can be created to better illustrate the sequence of structural deformation.
• Automatic calculation of the target displacement.
• Detailed and intuitive presentation of the analytical results; tables, charts and 3D plots featuring areas of plastic hinges and elements with damage are available.
• All the code-defined capacity checks are supported (shear capacity, chord rotation capacity, inter-storey drift level, beam-column joints checks).
• Checks presented on a table and on the 3D plot; the members where the capacity is exceeded are highlighted with red.
• Detailed technical report in PDF, RTF or HTML format; the content (text, plots and tables) and the size of the report are determined by the users.
• CAD drawings with plan views, members’ cross sections and reinforcement tables; specially created *.ctb files are included.
• Easy copying of all the data, tables and plots to any other Windows application.
• Possibility to easily send a model to Seismosoft, in the case of modeling or convergence problems, and get assistance by our team of specialists in nonlinear analysis.

Learn more about SeismoBuild features or download the free trial.

SeismoStruct is an award-winning Finite Elements package capable of predicting the large displacement behaviour of space frames under static or dynamic loading, taking into account both geometric nonlinearities and material inelasticity. Concrete, steel, frp and sma material models are available, together with a large library of 3D elements, such as nonlinear fibre beam-column element, nonlinear truss element, nonlinear infill panel element, nonlinear masonry elements, nonlinear link elements, etc., that may be used with a wide variety of pre-defined steel, concrete and composite section configurations. The program has been extensively quality-checked and validated, as described in its Verification Report. Some of the more important features of SeismoStruct are summarised in what follows:

• Completely visual interface. No input or configuration files, programming scripts or any other time-consuming and complex text editing requirements.
• Significantly faster analyses with the new parallel processing capabilities and a new sparse/profile solver.
• Full integration with the Windows environment. Input data created in spreadsheet programs, such as Microsoft Excel, may be pasted to the SeismoStruct input tables, for easier pre-processing. Conversely, all information visible within the graphical interface of SeismoStruct can be copied to external software applications (e.g. to word processing programs, such as Microsoft Word), including input and output data, high quality graphs, the models’ deformed and undeformed shapes and much more.
• With the Wizard facility the user can create regular/irregular 2D or 3D models and run all types of analyses on the fly. The whole process takes no more than a few seconds.
• With the Building Modeller the user can create real regular or irregular 3D reinforced concrete models within minutes and print tables containing all the model members and their characteristics.
• Easy input of infill panels and steel braces in the Building Modeller.
• New 3-sided, 2-sided and 1-sided jackets are available in the Building Modeller.
• Individual footings, Strip footings and Connecting beams are available for the modelling of foundation within the Building Modeller facility.
• Ten different types of analysis: response spectrum analysis, dynamic and static time-history, conventional and adaptive pushover, incremental dynamic analysis, eigenvalue, non-variable static loading, buckling analysis and tsunami nonlinear analysis.
• The applied loading may consist of constant or variable forces, displacements and accelerations at the nodes. The variable loads can vary proportionally or independently in the pseudo-time or time domain.
• The program accounts for both material inelasticity and geometric nonlinearity.
• A large variety of reinforced concrete, steel, composite and masonry sections are available.
• The spread of inelasticity along the member length and across the section depth is explicitly modelled in SeismoStruct allowing for accurate estimation of damage accumulation.
• Numerical stability and accuracy at very high strain levels enabling precise determination of the collapse load of structures.
• The innovative adaptive pushover procedure. In this pushover method the lateral load distribution is not kept constant but is continuously updated, according to the modal shapes and participation factors derived by eigenvalue analysis carried out at the current step. In this way, the stiffness state and the period elongation of the structure at each step, as well as higher mode effects, are accounted for. In particular the displacement-based variant of the method, due to its ability to update the lateral displacement patterns according to the constantly changing modal properties of the system, overcomes the inherent weaknesses of fixed-pattern displacement pushover, providing superior response estimates.
• SeismoStruct possesses the ability to smartly subdivide the loading increment, whenever convergence problems arise. The level of subdivision depends on the convergence difficulties encountered. When convergence difficulties are overcome, the program automatically increases the loading increment back to its original value.
• SeismoStruct’s processor features real-time plotting of displacement curves and deformed shape of the structure, together with the ability of pausing and re-starting the analysis.
• Features enabling easier convergence and possibility to display areas with plastic hinges or damage in 3D plot.
• Capacity checks in chord rotation and shear can be performed, according to the Eurocodes, the American Code for Seismic Evaluation and Retrofit of Existing Buildings (ASCE), the Italian National Seismic Code (NTC-18), the Greek Seismic Interventions Code (KANEPE) and the Turkish Seismic Evaluation Building Code (TBDY) and for all the limit states of the specified codes.
• Performance criteria can also be set, allowing the user to identify the instants at which different performance limit states (e.g. non-structural damage, structural damage, collapse) are reached. The sequence of cracking, yielding, failure of members throughout the structure can also be, in this manner readily obtained.
  Advanced post-processing facilities, including the ability to custom-format all derived plots and deformed shapes, thus increasing productivity of users.
  AVI movie files can be created to better illustrate the sequence of structural deformation.
• Possibility to easily create hundreds or thousands of SeismoStruct input files using the SPF creator module.
• SeismoStruct Batch module giving the ability to automatically execute numerous analyses in sequence.
• Possibility to easily send a model to Seismosoft, in the case of modeling or convergence problems, and get assistance by our team of specialists in nonlinear analysis.

Learn more about SeismoStruct features or download the free trial:

FRP Designer provides an efficient solution for designing FRP strengthening of reinforced concrete columns and beams by computing the strength of reinforced concrete members strengthened with FRP laminates.

In particular the software computes the bending and shear capacity of reinforced concrete members at first without FRP laminate strengthening and then with strengthening by FRP laminates specified by the user. This way the software provides a tool for designing the strengthening of a reinforced concrete member against bending and shear and also assess the effects of strengthening with various types of FRP laminates.

The properties of the existing members like geometry, reinforcement, materials, loads and code-related parameters can be easily introduced using a user-friendly visual interface. A large variety of commercially available FRP laminates is available in the software while the user can introduce custom FRP laminate types. Parameters associated to the FRP wrapping like Radius of corners, number of FRP layers etc can also be easily introduced in the program.

You can also get FRP Designer as part of the SeismoBuild program.

Learn more about FRP Designer features or download the free trial:

> FRP Designer 2024

SeismoSelect is an easy and efficient way to search, select, scale and download ground motion data from different strong motion databases that are available on-line. Different criteria may be employed as the parameters of interest, with which to carry out the searches. These include a target response spectrum, different ground motion parameters (e.g. PGA, PGV, Arias or Housner Intensity), information regarding the event (e.g. magnitude, faulting style location, date) or the recording site (e.g. Vs30, epicentral distance).

Based on these parameters the software carries out searches for sets of compatible records and provides ways to easily download the selected records.

More than 25 National Building Codes and various Regulations Worldwide

SeismoSelect can retrieve data from three strong motion databases: (i) the NGA-West 2 Ground Motion Database, (ii) the NGA-East Ground Motion Database, (iii) the ESM – Engineering Strong-Motion Database , (iv) the NGA-Subduction Ground Motion Database, and (v) the New Zealand Ground Motion Database.

The flat files of these databases are being employed locally for the selection and scaling of the records, and users should connect to the internet only to download the selected ground motions.

Finally, and due to its full integration with the Windows environment, SeismoSelect allows for numerical and graphical results to be copied to any Windows application (e.g. MS Excel, MS Word, etc.), noting that the plots characteristics can be fully customised from within the program itself.

Learn more about SeismoSelect features or download the free trial:

> SeismoSelect Support

• SeismoSignal constitutes an easy and efficient way to process strong-motion data, featuring a user-friendly visual interface and the capability of deriving a number of strong-motion parameters often required by engineer seismologists and earthquake engineers, such as:Fourier and Power spectra
• Elastic response spectra and pseudo spectra
• Overdamped and constant-ductility inelastic response spectra
• Root-mean-square (RMS) of acceleration, velocity and displacement
• Arias (Ia) and characteristic (Ic) intensities
• Cumulative absolute velocity (CAV) and specific energy density (SED)
• Acceleration (ASI) and velocity (VSI) spectrum intensity
• Housner intensity (HI)
• Sustained maximum acceleration (SMA) and velocity (SMV)
• Effective design acceleration (EDA)
• Predominant (Tp) and mean (Tm) periods
• Husid and energy flux plots
• Bracketed, uniform, significant and effective durations
• Number of effective cycles
• Damage index
• Maximum incremental velocity (MIV)
• Impulsivity index (IP Index)
• Average spectral acceleration (Sa,avg)

The program is able to read accelerograms saved in in different text file formats, which may then be filtered and baseline-corrected. Polynomials of up to the 3rd order may be employed for the latter, whilst three different digital filter types are available, all of which capable of carrying out, causal or acausal, highpass, lowpass, bandpass and bandstop filtering.

Finally, and due to its full integration with the Windows environment, SeismoSignal allows for numerical and graphical results to be copied to any Windows application (e.g. MS Excel, MS Word, etc.), noting that the characteristics plots can be fully customised from within the program itself.

Learn more about SeismoSignal features or download the free trial:

> SeismoSignal Support

SeismoSignal 3D constitutes an easy and efficient way to process strong-motion data in 2 (X+Y) or 3 (X+Y+Z)  dimensions, featuring a user-friendly visual interface and the capability of deriving a number of strong-motion parameters often required by engineer seismologists and earthquake engineers.

The program is able to read accelerograms saved in in different text file formats, which may then be filtered and baseline-corrected. Polynomials of up to the 3rd order may be employed for the latter, whilst three different digital filter types are available, all of which capable of carrying out highpass, lowpass, bandpass and bandstop filtering.

Furthermore, it is possible to open automatically zip files with records for all three components that have been with downloaded from the European Strong Motion Database (ESM) or the PEER Ground Motion Databases (NGA-West 2 and NGA-East).

Finally, and due to its full integration with the Windows environment, SeismoSignal 3D allows for numerical and graphical results to be copied to any Windows application (e.g. MS Excel, MS Word, etc.), noting that the characteristics plots can be fully customised from within the program itself.

• Orientation-Independent response spectra, RotD100, RotD50, RotD00 and RotDXX for any percentile value
• Orbit Plots
• Arias Intensity (Ia) for all three components X, Y and Z
• Cumulative Absolute Velocity for all three components X, Y and Z
• Peak ground values of the acceleration (PGA) for all three components X, Y and Z
• Peak ground values of the acceleration (PGA) for the RotD100 and the RotD00 spectra
• Peak ground values of the velocity (PGV) for all three components X, Y and Z
• Peak ground values of the velocity (PGA) for the RotD100 and the RotD00 spectra
• Peak ground values of the displacement (PGD) for all three components X, Y and Z
• Peak ground values of the displacement (PGA) for the RotD100 and the RotD00 spectra

Some of its features are:

• Simultaneous matching of a number of accelerograms, and then creation of a mean matched spectrum whose maximum misfit respects a pre-defined tolerance.
• Possibility of using this software in combination with records selection tools and records appropriateness verification algorithms to define adequate suites of records for nonlinear dynamic analysis of new or existing structures.
• Capability of reading single accelerograms defined in both single- or multiple-values per line formats (the two most popular formats used by strong-motion databases) or of reading a number of accelerograms at the same time (if they are defined in the single-value per line format).
• Creation of the target spectrum by following rules from a selection of more than 25 National Building Codes including Eurocode 8 rules, ASCE 41-17 and various Regulations worldwide, by computing the spectrum of a specific accelerogram or by simply loading a user-defined spectrum.

The following strong-motion parameters are then computed for the matched accelerograms:

• Elastic response spectra and pseudo-spectra
• Overdamped and constant-ductility inelastic response spectra
• Root-mean-square (RMS) of acceleration, velocity and displacement
• Arias (Ia) and characteristic (Ic) intensities
• Cumulative absolute velocity (CAV) and specific energy density (SED)
• Acceleration (ASI) and velocity (VSI) spectrum intensity
• Housner intensity
• Sustained maximum acceleration (SMA) and velocity (SMV)
• Effective design acceleration (EDA)
• Predominant period (Tp)
• Significant duration

In addition, SeismoMatch also features a module in which a user can combine many matched accelerograms in order to obtain a combined mean spectrum that fulfils the user’s requirements regarding maximum and mean misfit.

Finally, and due to its full integration with the Windows environment, SeismoMatch allows for numerical and graphical results to be copied to any Windows application (e.g. MS Excel, MS Word, etc.), noting that the plots characteristics can be fully customised from within the program itself.

Learn more about SeismoMatch features or download the free trial:

> SeismoMatch Support

This software can be used to generate suites of accelerograms for nonlinear dynamic analysis of new or existing structures. The program is capable of reading accelerograms and spectra saved in different text file formats. This collection of ground motion records and spectra is then used in the simulation phase for the definition of target spectrum or envelope shapes.

Currently, the target spectrum can be created by following rules from a selection of more than 25 National Building Codes including Eurocode 8 rules, ASCE 41-17 and various Regulations worldwide, by computing the spectrum of a specific accelerogram or by simply loading a user-defined spectrum. With both the target spectrum and the envelope type defined, an artificial accelerogram is generated and a comparison between its response spectrum and the target spectrum is given including the mean error in percentage, coefficient of variation, and PGA of the accelerogram.

Finally, due to its full integration with the Windows environment, SeismoArtif allows for numerical and graphical results to be copied to any Windows application (e.g. MS Excel, MS Word, etc.), noting that the characteristics of the plots can be fully customised from within the program itself.

Learn more about SeismoArtif features or download the free trial:

> SeismoArtif Support