Structural Seismic Engineering Group - SSEG IIT Gandhinagar

📢 𝗘𝘅𝗰𝗶𝘁𝗲𝗱 𝘁𝗼 𝘀𝗵𝗮𝗿𝗲 𝗼𝘂𝗿 𝗹𝗮𝘁𝗲𝘀𝘁 𝗽𝘂𝗯𝗹𝗶𝗰𝗮𝘁𝗶𝗼𝗻!

📝 𝗧𝗶𝘁𝗹𝗲: Experimental analysis of stress block parameters for normal and high-strength concrete and possible influence on strong-column-weak-beam philosophy
👨‍💻 𝗔𝘂𝘁𝗵𝗼𝗿𝘀: Sandesh Tripathi, Shivani Sharma, Dhiman Basu
📚 𝗝𝗼𝘂𝗿𝗻𝗮𝗹: Innovative Infrastructure Solutions

This study establishes concrete stress-strain models for normal and high-strength concrete. A procedure is proposed to construct the design stress-strain curve of concrete. The strain at peak stress is proposed as a function of the characteristic strength, whereas the ultimate strain is observed to be nearly independent of it. Additionally, the modulus of elasticity is observed to exhibit a linear relationship with the compressive strength. Further, the stress-block parameters for the design of beams and columns are modified. It is observed that the proposed modification does not affect the flexural strength of under-reinforced beams, but it leads to an underestimation of flexural strength in columns under axial load when conventional stress-block parameters are used.

🔗 Do check it out:

LinkedIn This link will take you to a page that’s not on LinkedIn

📢📢We are thrilled to announce our 𝗹𝗮𝘁𝗲𝘀𝘁 𝗽𝘂𝗯𝗹𝗶𝗰𝗮𝘁𝗶𝗼𝗻!

📝 Title: 𝗔𝗰𝗰𝗶𝗱𝗲𝗻𝘁𝗮𝗹 𝗘𝗰𝗰𝗲𝗻𝘁𝗿𝗶𝗰𝗶𝘁𝘆 𝘁𝗼 𝗔𝗰𝗰𝗼𝘂𝗻𝘁 𝗳𝗼𝗿 𝗧𝗼𝗿𝘀𝗶𝗼𝗻𝗮𝗹 𝗚𝗿𝗼𝘂𝗻𝗱 𝗠𝗼𝘁𝗶𝗼𝗻 𝗶𝗻 𝗘𝗾𝘂𝗶𝘃𝗮𝗹𝗲𝗻𝘁 𝗟𝗮𝘁𝗲𝗿𝗮𝗹 𝗙𝗼𝗿𝗰𝗲 𝗣𝗿𝗼𝗰𝗲𝗱𝘂𝗿𝗲

👨‍💻 Authors: Dhiman Basu, Falak Vats and Saksham Sood
📚 Journal: 𝗘𝗮𝗿𝘁𝗵𝗾𝘂𝗮𝗸𝗲 𝗘𝗻𝗴𝗶𝗻𝗲𝗲𝗿𝗶𝗻𝗴 & 𝗦𝘁𝗿𝘂𝗰𝘁𝘂𝗿𝗮𝗹 𝗗𝘆𝗻𝗮𝗺𝗶𝗰𝘀

This study evaluates the required accidental eccentricity to account for the torsional ground motion, arguably the most dominant contributor of accidental torsion. The proposed recommendation is based on the analysis of a wide range of one-storey torsionally coupled buildings subject to a suite of seismic events comprising the recorded orthogonal pair of horizontal accelerograms and the recorded torsional accelerogram. The final proposal considers all possible directionality of the horizontal pair given the same recorded torsional accelerogram. An example is also included to demonstrate the computation of system properties required to implement the proposed recommendation of accidental eccentricity in a multistorey building.

🔗 For more details:

Accidental Eccentricity to Account for Torsional Ground Motion in Equivalent Lateral Force Procedure Equivalent-lateral-force (ELF) procedure of seismic design considers accidental torsion by applying the design lateral force profile at an offset equal to accidental eccentricity from the CM. This pa...

📢📢Third Publication of this Month!

📝 Title: Capturing the Peak Response Over All Possible Orientations for Direction of Arrival of Multicomponent Seismic Excitation

👨‍💻 Authors: Falak Vats and Dhiman Basu
📚 Journal: Earthquake Engineering & Structural Dynamics

Ground motion is often recommended to be applied with all possible orientations relative to the plan layout of a structure, and the resulting maximum response for an engineering demand parameter (EDP) over all possible directions of arrival (DOAs) is considered in seismic design. The associated DOA is denoted as the critical orientation, which is expected to differ from one EDP to another. A description of the six-component acceleration time series completely defines the required ground motion inputs for most structures. This paper proposes a framework for the maximum response of an EDP over all possible DOAs and the associated critical orientation using three sets of response history analysis of the structure, followed by nominal post-processing. The proposed formulation is “mathematically exact” for linear-elastic systems. Nevertheless, it is observed based on a limited study that the critical orientation does not alter significantly owing to this inelastic excursion for simple structures. Based on this limited investigation, the proposed framework may conveniently be incorporated into routine seismic design to account for the maximum direction shaking of multicomponent seismic excitation.

🔗 For more details:

Capturing the Peak Response Over All Possible Orientations for Direction of Arrival of Multicomponent Seismic Excitation Ground motion is often recommended to be applied with all possible orientations relative to the plan layout of a structure, and the resulting maximum response for an engineering demand parameter (EDP...

Excited to share our latest publication!

📝 Title: Alternate Intensity Measure for Maximum Direction Shaking and Construction of the Associated Ground Motion Models
👨‍💻 Authors: Falak Vats and Dhiman Basu
📚 Journal: Soil Dynamics and Earthquake Engineering

This paper proposes Rotated RotD100 spectrum, a single-component spectrum rotated to align with the orientation of the RotD100 spectral ordinate at the period of interest as an alternate defination of maximum direction shaking. It preserves the RotD100 spectral ordinate at any specific period while avoiding overestimation at other periods. This defination is also theoretically consistent with the recent recommendation on alternate perspective critical orientation (https://doi.org/10.1016/j.soildyn.2025.109519), aiming to maximise the structural response. Therefore, the proposed intensity measure for maximum direction shaking should be preferred in scenario-based seismic performance assessment. A novel framework is proposed for developing the ground motion model (GMM) with Rotated RotD100 as the intensity measure by modifying RotD100 GMM. The proposed framework is demonstrated with a subset of the NGA-West2 database. Overall, the proposed framework and the Rotated RotD100 GMM are expected to be a valuable tool in several earthquake engineering applications, such as site-specific seismic hazard analysis and scenario-based performance assessment.

🔗 Do check it out:
https://authors.elsevier.com/a/1lNSJytxOa-P-

authors.elsevier.com

📢 Publication Alert! Check our Latest Publication!

📝 Title: An alternate double‑bounded distribution for environmental variables and its possible application to wind speed modeling
👨‍💻 Authors: Aniket Panchal and Dhiman Basu
📚 Journal: International Journal of Advances in Engineering Sciences and Applied Mathematics

Natural phenomena like wind speed, flood levels, and precipitation are physically bounded phenomena. However, prevalent statistical models used in climate and environmental risk assessment don’t fully account for these natural limits. In our latest work, we developed the Generalized Double Bounded Distribution (GDBD) using principles similar to extreme value theory, tailored specifically for double-bounded environmental data.

The developed distribution is validated against Generalized Extreme Value (GEV) distribution by fitting to recorded wind speed data.

This work supports the case for using bounded statistical distributions like GDBD in the characterization of wind hazards and for more reliable performance assessment of structures exposed to extreme wind events.

🔗 Check out the link:

An alternate double-bounded distribution for environmental variables and its possible application to wind speed modeling - International Journal of Advances in Engineering Sciences and Applied Mathematics Natural phenomena such as wind speed, flood levels, precipitation, and many others exhibit bounded behavior on both ends due to physical constraints. This paper introduces an alternative Generalized Double Bounded Distribution (GDBD), developed using a principle similar to the extreme value theory t...

📣 New Publication Alert | Bulletin of Earthquake Engineering 📣

𝐃𝐞𝐯𝐞𝐥𝐨𝐩𝐢𝐧𝐠 𝐆𝐫𝐨𝐮𝐧𝐝 𝐌𝐨𝐭𝐢𝐨𝐧 𝐏𝐫𝐞𝐝𝐢𝐜𝐭𝐢𝐨𝐧 𝐄𝐪𝐮𝐚𝐭𝐢𝐨𝐧𝐬: 𝐀𝐧 𝐀𝐥𝐭𝐞𝐫𝐧𝐚𝐭𝐞 𝐌𝐞𝐭𝐡𝐨𝐝𝐨𝐥𝐨𝐠𝐲 𝐚𝐧𝐝 𝐈𝐭𝐬 𝐈𝐦𝐩𝐥𝐞𝐦𝐞𝐧𝐭𝐚𝐭𝐢𝐨𝐧 𝐰𝐢𝐭𝐡 𝐚 𝐒𝐮𝐛𝐬𝐞𝐭 𝐨𝐟 𝐍𝐆𝐀-𝐖𝐞𝐬𝐭𝟐 𝐃𝐚𝐭𝐚𝐛𝐚𝐬𝐞

Authors: Falak Vats & Dhiman Basu
Journal: 𝐁𝐮𝐥𝐥𝐞𝐭𝐢𝐧 𝐨𝐟 𝐄𝐚𝐫𝐭𝐡𝐪𝐮𝐚𝐤𝐞 𝐄𝐧𝐠𝐢𝐧𝐞𝐞𝐫𝐢𝐧𝐠

Ground-motion-prediction-equations (GMPEs) play a critical role in seismic hazard analysis. However, the conventional methods for developing GMPEs, which rely on functional forms and assumptions like homoscedasticity, can introduce biases. This paper discusses Consistent Spectral Shape (CSS) approach, a novel framework for GMPE construction that captures the underlying physics by working directly with the database instead of using pseudo-physics-based functional forms. While the application of this approach on the Himalayan Region was already published elsewhere (https://doi.org/10.1016/j.soildyn.2023.108312), this paper presents the underlying theory and its implementation over the NGA-West2 database.
CSS Framework decouples the logarithmic mean spectrum into two components: logarithmic spectral shape and logarithmic mean peak ground acceleration (normalizing factor). This decoupling enables a specific study of the spectral shape, allowing for an investigation of how it varies across different sets of independent variables and different definitions of intensity measures. Additionally, the paper also describes methods to account for aleatory variability depending on the existence of systematic trend against seismological parameters. The framework is demonstrated through its application to the NGA-West2 database for five spectral acceleration definitions: (a) RotD50; (b) RotD100; (c) Geo-mean; (d) GMRotD50; and (e) GMRotD100.

⛓️‍💥Read the full article here: https://doi.org/10.1007/s10518-025-02185-y

Developing ground motion prediction equations: an alternate methodology and its implementation with a subset of NGA-West2 database - Bulletin of Earthquake Engineering Ground-motion-prediction-equations (GMPEs) play a critical role in seismic hazard analysis. However, the conventional methods for developing GMPEs, which rely on functional forms and assumptions like homoscedasticity, can introduce biases. The Consistent Spectral Shape (CSS) approach introduces a no...

📣 New Publication Alert!

We are excited to share our second publication this week by Falak Vats and Dhiman Basu, titled "An alternate perspective on the critical orientation of horizontal pair of seismic excitations: Theory and illustrations," in Soil Dynamics and Earthquake Engineering.

Ground motion is often recommended to be applied with all possible orientations relative to the plan layout of a structure and the resulting maximum response for an engineering-demand-parameter (EDP) over all possible direction of arrivals (DOAs) is considered in seismic design. The associated DOA is denoted as the critical orientation, which is expected to differ from one EDP to another. This paper enhances the understanding of critical orientation for horizontal ground motion pairs when applied to the base of a structure. Given that any structural response comprises the contributions from individual modes, even under inelastic excursion, the maximization of modal responses for the first few modes would be sufficient to define the critical orientation for most of the EDPs. In line with this, the theoretical background to establish a concept of modal orientation is presented in this paper. The analysis for the modal response of a building against a pair of orthogonal horizontal excitations is theoretically equivalent to the analysis against the associated single component representation along this orientation. The critical orientation is proven to be the difference between the modal and spectral orientations. Although this development is based on linear analysis, it is demonstrated to be applicable to buildings undergoing inelastic excursion under moderate-to-strong shaking. The proposed recommendations on critical orientation should be incorporated into seismic design and performance assessment practices.

⛓️‍💥Check out the publication here:

Redirecting

📣 New Publication Alert!
We are excited to announce the latest publication by our research group co-authored by Dhiman Basu and Falak Vats, titled "An application of multicomponent directional-cum-modal combination rule: routine seismic design and performance assessment," in Innovative Infrastructure Solutions.

A directional-cum-modal combination (DCM) rule was recently reported by the authors to combine the directional and the modal responses of a structure subjected to multicomponent ground motion described by response spectral representation (doi.org/10.1002/eqe.3669). This present paper explores the task of incorporating the same DCM rule within the framework of seismic design/performance assessment, which is based on the design spectrum rather than the response spectrum. The framework is proposed to enable incorporation in the seismic performance assessment (in terms of Demand-to-Capacity ratio) by constructing a single set representation of ground motion inputs consistent with the given single component target spectrum (preferably based on horizontal components). Examples are presented as sample illustrations of the proposed framework using a couple of buildings and different representative suites of ground motions demonstrating the efficacy of the proposed framework. In summary, the proposed framework enables the incorporation of the multicomponent ground excitation (described through spectral representation) in the routine practice of seismic design and performance assessment.

⛓️‍💥Check out the link below for early access:
https://rdcu.be/elLKt

rdcu.be

📣 New Publication Alert!
We’re pleased to share one of the recent publications from our research group, co-authored by Narsiram Gurjar Awana and Dhiman Basu, titled: "Selection and Scaling of the Positively Correlated Ground Motion Suite for Seismic Performance Assessment," in Journal of Earthquake and Tsunami.

Selection and scaling of ground motion suite(s) followed by response history analysis form the main stem of pre-processing for the seismic design and performance assessment of structures. Ground motion selection (and scaling) frameworks reported in the prior art recommend the construction of target spectra taking into account the underlying correlation or covariance matrix. A number of target spectra in the order of thousands is generally required to represent/capture the true correlation structure accurately. However, seismic performance assessment usually involves a set of approximately 10 to 20 ground motions due to the inherent computational expenses and the limited number of recorded ground motions in the available database. This, in turn, leads to the failure probability of an engineering demand parameter (EDP) sensitive to the selection of a number of ground motion records in the suite, and the resulting failure probability could be potentially under- or over-estimated. Such underestimation may not be acceptable for critically important structures (such as tall structures, Nuclear Power Plant, etc.). One possible way out in such a case, without increasing the number of ground motion records/spectra in a suite, is to construct the target spectra using positive correlation, and in other words, using the fractile spectra. This paper proposes a framework for the selection and scaling of the positively correlated ground motion suite. Novelty involved in the proposed framework is demonstrated through an example of ground motion selection exercise, followed by the seismic performance assessment of a structure. The resulting various EDP hazards are compared with a widely adopted framework in the prior art to illustrate the possible impact of selecting a positively correlated ground motion suite.

⛓️‍💥Checkout this interesting publication:

Journal of Earthquake and Tsunami JET is a forum to report on research in Geological and Seismological Setting; Ground Motion, Site and Building Response; Tsunami Generation, Propagation, Damage and Mitigation.

𝗧𝗵𝗿𝗶𝗹𝗹𝗲𝗱 𝘁𝗼 𝗮𝗻𝗻𝗼𝘂𝗻𝗰𝗲 𝗮 𝗻𝗲𝘄 𝗽𝘂𝗯𝗹𝗶𝗰𝗮𝘁𝗶𝗼𝗻 𝘁𝗵𝗶𝘀 𝘄𝗲𝗲𝗸!

The routine practice of seismic design and performance assessment employs three translational components of ground motion, but their spatial variability is rarely considered. As a part of our continued efforts on seismic hazard and ground motion characterization, Narsiram Gurjar (from his PhD thesis) has proposed a comprehensive framework that integrates the conditional simulation of multicomponent (three translational and three rotational) spatially varying ground motion field (accounting for the site-specific epistemic uncertainties) with the seismic performance assessment of a structure. This is to offer dual objectives: i) understanding the influence of Spatially varying ground motion (SVGM) field on different engineering demand parameters (EDPs); and ii) influence of multicomponent excitation on the EDPs. Two medium-span reinforced concrete highway bridges are considered for illustration.

𝗖𝗵𝗲𝗰𝗸 𝗼𝘂𝘁 𝘁𝗵𝗲 𝗹𝗶𝗻𝗸 𝗳𝗼𝗿 𝗳𝘂𝗿𝘁𝗵𝗲𝗿 𝗱𝗲𝘁𝗮𝗶𝗹𝘀 𝗶𝗳 𝘆𝗼𝘂 𝗮𝗿𝗲 𝗶𝗻𝘁𝗲𝗿𝗲𝘀𝘁𝗲𝗱:
https://www.sciencedirect.com/science/article/abs/pii/S0267726125000314

𝗣𝘂𝗯𝗹𝗶𝗰𝗮𝘁𝗶𝗼𝗻 𝗗𝗲𝘁𝗮𝗶𝗹𝘀:
Title: A framework to integrate conditional simulation of multicomponent spatially varying ground motion field with seismic performance assessment and its application to medium-span bridges
Journal: Soil Dynamics and Earthquake Engineering
Authors: Narsiram Gurjar Awana and Dhiman Basu

www.sciencedirect.com

We are pleased to announce a new publication of Shivani Sharma and Sandesh Tripathi, “Enhancing Quality Control in the Mix Design of High-Strength Concrete Using a Capacity-Based Approach,” in the International Journal of Concrete Structures and Materials.

This paper aims to revisit the existing mix design method given in IS 10262:2019 through a capacity-based approach. The approach involves identifying the possible failure modes in concrete and eliminating the undesirable ones leading to significant reduction in dispersion. This is accomplished by utilising coarse aggregates that meet a specific minimum strength requirement or threshold which is determined through a priori estimating the cohesion and friction angle of the concrete. This paper also offers a simple and approximate test procedure to estimate the aggregate's compressive strength reasonably which is essential for the capacity-based mix design. The results indicate that M95 concrete is achieved with a low standard deviation and coefficient of variation (~ 3%), falling in class of excellent quality control as per ACI 214R-11. This quality control is crucial in seismic structural design as variations in concrete strength is likely to negate the underlying principle of strong column–weak beam philosophy resulting in the triggering of undesirable shear modes of failure.

Please check the following link for the paper.

Enhancing Quality Control in the Mix Design of High-Strength Concrete Using a Capacity-Based Approach - International Journal of Concrete Structures and Materials The mix design of concrete is an important aspect that affects its strength and durability. This paper aims to revisit the existing mix design method given in IS 10262:2019 through a capacity-based approach. The approach involves identifying the possible failure modes in concrete and eliminating the...

Thrilled to announce another publication this week!

Direct recommendations on considering the rotational hazards in seismic design are not presently available in international practice. As a part of our continued efforts on seismic hazard and ground motion characterization, Ravi Kanth Sriwastav (from his PhD thesis) has proposed the rocking and torsional spectra [collectively called rotational spectra (Rot)] for scenario- and intensity- based seismic performance assessment. These recommendations are based on scaling of the associated horizontal spectra (H) through respective Rot/H spectra but contingent to the governing seismological parameters. The median level recommendations on the Rot/H spectral shape are also demonstrated to apply to the design level (of a particular facility located in a specific site, which is also governed by a scenario) under certain assumptions. Median Rotational- to median Horizontal- PGA is also recommended for intensity-based assessment.

Check out the link for further details if you are interested.

rdcu.be