Including Soil Structure Interaction Research Articles

Jellyfish search optimization for tuned mass dumpers for earthquake oscillation of elevated structures including soil–structure interaction

Jellyfish search optimization for tuned mass dumpers for earthquake oscillation of elevated structures including soil–structure interaction

Fragility curves for existing reinforced concrete buildings, including soil–structure interaction and site amplification effects

SSI and site amplification effects are investigated as influences on the seismic fragility of existing reinforced concrete moment-resisting frame and dual frame-wall system buildings supported on shallow foundations without interconnecting beams. We build upon a holistic methodology that accounts for site amplification and soil–foundation–structure interaction effects using a modular approach. We calculate fragility curves based on nonlinear dynamic analyses for various building structural typologies and geometries, infill conditions, code provisions, and soil profile materials and dynamic characteristics. We demonstrate that site amplification during earthquakes may significantly increase the fragility of the soil–foundation–structure system, which is reflected in its vulnerability. Moreover, SSI is especially prevalent for buildings on soft soil profiles and might modify their fragility. We propose a modular method to include site amplification and/or soil–structure interaction effects in a large-scale earthquake vulnerability assessment using fragility modifiers, which we express using an easy-to-code equation form.

Factors affecting the seismic collapse performance of realistic low‐rise braced frame buildings, including soil structure interaction and foundation flexibility

AbstractPrevious computational studies of short‐period buildings have shown increasing collapse probabilities with decreasing building period; a trend that has not been observed in past earthquakes. In this study, collapse performances of twelve short‐period steel special concentrically braced frame (SCBF) building archetypes were examined using dynamic analysis and the methods described in FEMA P‐695 to investigate this gap between analytically predicted and historically observed collapse rates. The archetypes varied key design and modeling parameters that could influence the behavior. These parameters included number of stories, level of design seismicity, redundancy, the inclusion of soil‐structure interaction (SSI) and foundation flexibility, and the removal of reserve moment frame resistance in modeling. Practicing engineers designed the archetypes resulting in realistic designs, including overstrength values representative of this building type. The calculated overstrength values were much higher than those found in previous studies, largely a result of the archetype building layouts, brace width‐to‐thickness ratio limitations, and the large differences between tension and compressive brace strength that occur when design demands are low. The higher overstrength values found in this study resulted in lower probabilities of collapse, relative to previous collapse studies and showed that probabilities of collapse decreased with decreasing period. Additionally, the probability of collapse increased significantly for the nonredundant archetype, but changed insignificantly for the archetype without reserve moment frame capacity. Inclusion of SSI and foundation flexibility resulted in a complete change in behavior where braces remained elastic and the braced frames rocked on their foundations, resulting in decreased collapse probabilities.

Strategies for Modeling Partial Pile Head Fixity in Laterally Loaded Pier Foundations

When designing pile groups subjected to lateral loading, modeling and analysis of the connections between piles and the overlying pile caps require careful consideration. For a given pier foundation, characterization of the pile-to-cap connections typically corresponds to one of: pinned (no moment transfer); fixed (moment transfer up to pile rotational capacity); or, partially fixed pile head conditions. The present study aims to provide bridge engineers with practical resources for modeling laterally loaded pile group behaviors, in association with partially fixed pile head conditions. Modeling strategies are presented for both relatively simple (i.e., highly idealized) configurations, as well as for an array of conceivable pier foundations. In particular, an analytical approach is presented, which is suitable for preliminary design of configurations analyzed in a linear elastic manner, and on a representative-pile basis. For nonlinear analysis of pile groups (including soil–structure interaction), a search algorithm is developed that converges on a given target level of partial pile head fixity and associated pile group response (e.g., group lateral displacements, pile head moments). The search algorithm is utilized to investigate 20 unique pier foundation configurations under various lateral load intensities and across target levels of partial fixity. Pairing of the computed foundation responses with the levels of partial fixity, in the ensemble, is intended to serve as a resource to bridge engineers when making initial estimates to model partially fixed pile head conditions.

Adaptive-passive tuned mass damper for structural aseismic protection including soil–structure interaction

As one of the most traditional vibration mitigation devices, tuned mass dampers (TMDs) are applied widely in aseismic protection of building structures. The control effect of a passive TMD is depended on its parameters, especially the frequency ratio. Nevertheless, passive TMDs are high sensitive to the frequency detuning issue, and a mistuned TMD will lose its aseismic protection. Soil-structure interaction (SSI) will deviate the structural frequency and lead to a mistuned TMD. Besides, different soil conditions will lead to different frequency deviations of the primary structure. However, it may be difficult to obtain parameters of the soil exactly. To solve this problem, a recently developed adaptive-passive eddy current pendulum TMD (APEC-PTMD) is applied to a benchmark 40-story tall building including SSI in this study, and four different soil conditions are considered. The APEC-PTMD can identify the optimal TMD frequency in the building with different soil types, and then retune itself through adjusting the pendulum length, and also the air gap between the conduct plate and permanent magnets to reset its damping ratio. Therefore, no prior knowledge of the soil condition is needed for the APEC-PTMD. To verify the aseismic protection effect, 44 far-field earthquake excitations are chosen, and two passive TMDs are used for comparison, while one is optimized for the base-fixed structure and the other is optimized based on the dense-soil model. The passive TMD will become mistuned when SSI is considered or soil parameters are changed, while APEC-PTMD can adapt to the structural dominant frequency with different SSI. Therefore, it always works as a passive TMD with well-tuned parameters. Results show that the APEC-PTMD has a better aseismic protection than the passive TMD, especially in the soft-soil model, and it has an excellent control effect compared to the without TMD case at the same time.

Optimal Performance-Based Configurations of Stiffness and Strength Centers in Multi-Story Wall-Frame Asymmetric Buildings Including Soil–Structure Interaction Effects

ABSTRACT In this paper, the probabilistic performance-based approach is adopted to evaluate the seismic performance of multi-story reinforced concrete wall-frame asymmetric buildings considering soil–structure interaction (SSI) and identify appropriate stiffness and strength centers configurations. A group of fixed- and flexible-base models with different stiffness and strength eccentricities were considered for parametric studies, and their seismic performance was compared in three different limit states. The optimum configuration of centers was found to be a function of base condition and performance objective. The proposed configurations can be adopted in the performance-based design of asymmetric buildings. Furthermore, the results indicate a detrimental effect of SSI in the Life Safety and Collapse Prevention limit states.

Seismic Response of Skewed Integral Abutment Bridges under Near-Fault Ground Motions, Including Soil–Structure Interaction

Studies on the seismic response of skewed integral abutment bridges have mainly focused on response under far-field non-pulse-type ground motions, yet the large amplitude and long-period velocity pulses in near-fault ground motions might have significant impacts on bridge seismic response. In this study, the nonlinear dynamic response of an skewed integral abutment bridge (SIAB) under near-fault pulse and far-fault non-pulse type ground motions are analyzed considering the soil–structure interaction, along with parametric studies on bridge skew angle and compactness of abutment backfill. For the analyses, three sets of near-fault pulse ground motion records are selected based on the bridge site conditions, and three corresponding far-field non-pulse artificial records are fitted by their acceleration response spectra. The results show that the near-fault pulse type ground motions are generally more destructive than the non-pulse motions on the nonlinear dynamic response of SIABs, but the presence of abutment backfill will mitigate the pulse effects to some extent. Coupling of the longitudinal and transverse displacements as well as rotation of the bridge deck would increase with the skew angle, and so do the internal forces of steel H piles. The influence of the skew angle would be most obvious when the abutment backfill is densely compacted.

Dynamic analysis of onshore wind turbines including soil–structure interaction

Wind turbines are very sensitive structures. Their slender nature induces a low natural frequencies range, and it combined with spectrum with low frequency of vibration can be very unsafe. Thus, it is of a significant importance to analyze the dynamic behavior of these structures. Considering this, the present study aims to evaluate the dynamic performance of wind turbines via two analytical models, investigating three different conditions and how each one of these will affect in the results. The three aspects are: the influence of the operational condition (parked and rotating), the influence of the SSI and the influence of the rotor velocity. The NREL 5 MW wind turbine will be the source of properties for the tower, nacelle and rotor of the models. The models utilize multi-degree of freedom to represent a horizontal axes onshore wind turbine; moreover, the Euler–Lagrangian approach is used to process the dynamic analysis. The first model was developed using rotating blades modeled as continuous beams. The whole model has eight degrees of freedom. The blades are analyzed as a system of two degrees of freedom, i.e., it is possible to vibrate in the in-plane and out-of-plane directions. They are connected in the center of the tower–nacelle represented by a mass–spring corresponding to a system of two degrees of freedom, that is, it can also have vibrations in the in-plane and out-of-plane directions. The second model has the same characteristics of the first; however, it is included in it a foundation modeled like a spring with bidirectional rotational stiffness. In this way, it is possible, from this model, to study the soil–structure interaction (SSI). Soil stiffness and damping properties were acquired from DNV/Riso standards are used as a comparison. A wind load and an earthquake are used as the source of vibration to the models. The main objective, then, is to evaluate the impact of three different conditions (as previously mentioned) through the dynamic response obtained from the two models. From the results, it is perceived that the responses of the wind turbine in the operating condition are much larger than those in the parked condition; SSI can affect the responses of the tower considerably; however, it does not have a significant effect on the vibrations occurring in the plane of rotation of the blades. Finally, it is perceived that the amplitude of the response increase with the velocity of the rotor, in general.

Fragility evaluation of integral abutment bridge including soil structure interaction effects

Contrast to the conventional jointed bridge design, integral abutment bridges (IABs) offer some marked advantages like reduced maintenance and enhanced service life of the structure due to elimination of joints in the deck and monolithic construction practices. However, the force transfer mechanism during seismic and thermal movements is a topic of interest owing to rigid connection between superstructure and substructure (piers and abutments). This study attempts to model an existing IAB by including the abutment backfill interaction and soil-foundation interaction effects using Winkler foundation assumption to determine its seismic response. Keeping in view the significance of abutment behavior in an IAB, the probability of damage to the abutment is evaluated using fragility function. Incremental Dynamic Analysis (IDA) approach is used in this regard, wherein, nonlinear time history analyses are conducted on the numerical model using a selected suite of ground motions with increasing intensities until damage to abutment. It is concluded from the fragility analysis results that for a MCE level earthquake in the location of integral bridge, the probability of complete damage to the abutment is minimal.

Interval Type-2 Fuzzy Hybrid Control of a High-Rise Building Including Soil–Structure Interaction Under Near-Field and Far-Field Ground Motions

The interval type-2 fuzzy logic controller (IT2FLC) has emerged as one of the most effective high-tech control strategies to improve the performance of structures under near-field and far-field ground motions. The present study discusses the application of this strategy in the hybrid control of the behaviour of a real high-rise shear building by considering soil–structure interaction. In this regard, a hybrid control technique, consisting of a tuned mass damper (TMD) and a magneto-rheological (MR) damper is proposed. Using an MR damper on a TMD (MR + TMD) helps to reduce the seismic responses of a high-rise building in soil–structure interaction. The utilization of this hybrid device is very useful because it does not require huge power sources. By applying the observer–teacher–learner–based optimization (OTLBO) method, the fuzzy rules of IT2FLC, the TMD parameters, and the voltage of the MR damper have been optimized for a fifteen-storey shear building under four seismic near-field and far-field excitations. Minimization of the peak displacement of the top floor by using the square root of sum of squares (SRSS) of each response to each earthquake was utilized as the optimization criterion. Then, the optimized type-2 fuzzy rules and optimized TMD parameters were examined under seven new earthquake records in the fifteen-storey building. The results obtained by comparing the proposed control and uncontrolled systems in terms of the structure interaction with soft and dense soils show that the IT2FLC- using OTLBO is an efficient control method. It is also shown that the responses of this building to the hybrid controller have been effectively improved.

Dynamic analysis of a multi-span simply supported prestressed concrete bridge with restrainers and seismic isolation devices

The Nonlinear F.E. code Structural Analysis Program (SAP) in which the primary nonlinear characteristics of bearings, impact elements and steel restrainer cables considered herein in order to investigate the dynamic analysis of a multi-span simply supported MSSS prestressed concrete bridge, equipped with steel restrainer cables and Lead Rubber Bearings LRB devices including Soil Structure Interaction (SSI) effects. A MSSS bridge with restrainer cables and lead rubber bearings at the two abutments and intermediate bents located in North Algeria is selected according to RPOA for seismic design category 1 is considered in this study. A detailed 3D nonlinear analytical model of study bridge subjected to three components identical seismic excitation including pounding elements, restrainer cables and bearing devices at expansion joints is developed. The nonlinear characteristics of theses boundary elements are represented by bilinear hysteretic models. Under strong seismic excitations, the large longitudinal displacements result the collision between bridge decks or even unseating of these decks at expansion joints of MSSS bridge. Finally, the study reveals among others that in order to prevent deck unseating resulting from restrainer failures and subsequent bridge collapse, particular attention should also be given to proper design of nonlinear characteristics of restrainers and bearing devices.

Effect of Number of Stories on the Seismic Soil Structure Interaction Performance of Midrise Frame Structures

When an earthquakes hits, a state of emergency is declared that shakes lives and infrastructures and provokes aftershocks including fires and medical emergencies. The response of midrise concrete frame structures to a seismic excitation is related to the dynamic interaction between the structure, foundation and soil called soil structure interaction (SSI). To study the effect of structures’ number of stories on the seismic behavior of midrise concrete frame buildings including soil structure interaction effects, 5 to 15 stories structures were simulated by performing 3D time history nonlinear finite element simulations using Abaqus under the influence of El-Centro (1940) and Northridge (1994) earthquakes. The models consisted of frame structures supported by raft foundation and rested on silty sandy soil block. The results presented in terms of story lateral deflection, inter-storey drift, shear force, foundation rocking and response spectrum show that structures’ number of stories significantly affect SSI effects and increasing story number can end in structures’ collapse in some cases.

A research on optimum designs of steel frames including soil effects or semi rigid supports using Jaya algorithm

The effect of soil foundation plays active role in optimum design of steel space frames when included. However, its influence on design can be calculated after a long iterative procedure. So it requires longer computer time and more computational effort if it is done properly. The main purpose of this study is to investigate how these effects can be calculated in more practical way in a shorter time. The effects of semi-rigid column bases are taken into account in optimum design of steel space frames. This study is carried out by using JAYA algorithm which is a novel and practical method based on a single revision equation. The displacement, stress and geometric size constraints are considered in the optimum design. A computer program is coded in MATLAB to achieve corporation with SAP2000-OAPI (Open Application Programming Interface) for optimum solutions. Four different steel space frames including soil structure interaction taken from literature are investigated according to different semi-rigidly supported models depending on different rotational stiffness values. And the results obtained from analyses are compared with the results available in reference studies. The results of the study show that semi-rigidly supported systems in the range of appropriate rotational stiffness values offer practical solutions in a very short time. And close agreement is obtained with the studies on optimum design of steel space frames including soil effect underneath.

Coupled‐two‐beam discrete model for dynamic analysis of tall buildings with tuned mass dampers including soil–structure interaction

SummaryAn equivalent coupled‐two‐beam discrete model is developed for time‐domain dynamic analysis of high‐rise buildings with flexible base and carrying any number of tuned mass dampers (TMDs). The equivalent model consists of a flexural cantilever beam and a shear cantilever beam connected in parallel by a finite number of axially rigid members that allows the consideration of intermediate modes of lateral deformation. The equivalent model is applied to a shear wall–frame building located in the Valley of Mexico, where the effects of soil–structure interaction (SSI) are important. The effects of SSI and TMDs on the dynamic properties of the shear wall–frame building are shown considering four types of soil (hard rock, dense soil, stiff soil, and soft soil) and two passive damping systems: a single TMD on its top (1‐TMD) and five uniformly distributed TMDs (5‐TMD). The results showed a great effectiveness of the TMDs to reduce the lateral seismic response and along‐wind response of the shear wall–frame building for all types of soils. Generally speaking, the dynamic response increases as the flexibility of the foundation increases.

Simulation analysis of TMD controlled building subjected to far- and near-fault records considering soil-structure interaction

This study aims to investigate the performance of a tuned mass damper (TMD) in mitigating the dynamic response of buildings to far- and near-fault earthquake records including soil–structure interaction (SSI) effects. The selected records ensure near-fault with forward directivity (FD) and near-fault with fling. The effects of certain parameters of the installed TMD, such as the mass, the frequency and the damping ratios have been investigated using a developed MATLAB code. Displacement, velocity, acceleration, and energy responses from the analysis of the building model subjected to each of the considered faults were numerically calculated. The obtained numerical simulation results for the cases without and with including the SSI effects are comparatively presented and evaluated for the building model with a TMD damper. The presented results clearly show that there is a more seismic demand on an induced response for buildings excited by near fault records with fling. In addition, the inclusion of SSI increases the induced responses and alters the role of TMD in reducing the superstructure responses.

Soil-pile-superstructure interaction effects in seismically isolated bridges under combined vertical and horizontal strong ground motions

This paper presents a deterministic analysis carried out to study the influence of coupled vertical and horizontal ground motions on the response of an isolated bridge (or soil-pile-bridge system) considering soil-pile-superstructure effects. Towards this end, an advanced 3D finite element model is developed to evaluate the effects of combined Vertical Component (VC) and Horizontal Component (HC) of ground motion on the structural elements of the bridge including Soil Structure Interaction (SSI). Non-linear time-history analysis is carried out under strong ground motions using an advanced soil plasticity model for non-liquefiable soil. Three different bridge configurations consisting of (i) simply-supported girders (SSERB), (ii) continuous girder with fixed bearing (CFB) and (iii) continuous girder with elastomeric bearing (CERB) are considered. Ground motion selection procedure was applied among 21,000 records to select suitable ground motions for nonlinear time-history analysis. Critical damage parameters in the structural elements under the combined HC and VC of the ground motion are compared with those under only the HC of the ground excitation. Results indicate that the vertical components produce significant amplification in the pier's axial load with different lower and upper bounds for different seismic isolation systems. The Influence of higher modes on results of Incremental Dynamic Analysis (IDA) are presented for the different structural elements in a deterministic framework. The variations of shear capacity and demand are presented by IDA and the combined spectral acceleration is implemented as an Intensity Measure (IM) due to the inclusion of higher order modes. The simply-supported and continuous girder with elastomeric bearings have a trend for a higher drift ratio than the continuous girder with the fixed-bearings system under vertical excitation. Furthermore, the variation of axial loads and pile-cap displacements are highlighted with and without VC for piles at piers and abutments. In addition, pile-cap displacements, influence of bridge higher modes and VC effects on Soil-Pile-Superstructure Interaction (SPSI) relations are investigated with respect to frequency content of the ground motion. The kinematic and inertial SPSI effects on seismic isolation systems including VC are also explored comparatively. The influence of elastomeric bearing on SSI reduction was investigated by comparing the relative response of the superstructure, Free-Field and Foundation Input Motion (FIM) at the pile head in the frequency domain. The new information presented in this paper will be useful for realistic design of bridges in seismic areas considering coupled HC and VC of the seismic excitation.

Criteria and guidance for the design of integral bridges

The design and implementation of integral and semi-integral bridges has grown in prominence in New Zealand practice over the last two decades, and bridge designers in the country refer to the New Zealand Transport Agency (NZTA) Bridge Manual for design guidance. However, several issues related to the design and construction of integral bridges were identified as requiring either further investigation or clearer guidance for local design practice. These included non-seismic effects such as concrete creep, shrinkage and temperature, seismic effects and geotechnical issues including soil–structure interaction. Particularly, it was noted that there are no well-established earthquake design procedures for bridges with integral abutments and that the topic of soil–structure interaction required further guidance. NZTA research report 577, published in November 2015, was developed to sit alongside the Bridge Manual and provide local engineers with the necessary guidance for the design of integral bridges, including a description of the issues that need consideration to ensure excellent long-term performance. Report 577 also contains details of a review of the performance of numerous existing integral bridges in both New Zealand and California that have been subject to strong seismic events. This paper discusses the key issues for consideration in the design of integral bridges in non-seismic and seismic regions and the key recommendations for addressing these issues, and also provides examples of documented performance of some integral bridges in New Zealand.

Correction to: Seismic control of buildings with active tuned mass damper through interval type-2 fuzzy logic controller including soil–structure interaction

Correction to: Seismic control of buildings with active tuned mass damper through interval type-2 fuzzy logic controller including soil–structure interaction

Seismic control of buildings with active tuned mass damper through interval type-2 fuzzy logic controller including soil–structure interaction

This paper presents the application of interval type-2 fuzzy logic controller (IT2FLC) in ATMD for the response control of a building considering soil–structure interaction (SSI). One of the main constraints of the current fuzzy systems is their inability to consider uncertainty in fuzzy rules. Interval type-2 fuzzy systems have the ability to handle this deficiency. It also takes into account uncertainty in loading and structural behavior. To evaluate the influence of soil types on the behavior of structure, an 11-story shear building is used. This structure has been analyzed under the earthquake excitations recommended by the International Association of structural control (IASC) committee. The uncontrolled and controlled responses of structure with ATMD through IT2FLC are calculated with and without SSI effects. Numerical results indicate that SSI would significantly affect the structural response of the building. It is also found that when a structure is built on soft soil sites, the effectiveness of ATMD with IT2FLC in the case of suppressing the structural response is increased.

RETRACTED: Response of steel moment and braced frames subjected to near-source pulse-like ground motions by including soil-structure interaction effects

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor-in-Chief. It has come to our attention that there is significant duplication of text and content between this Soil Dynamics and Earthquake Engineering article and an earlier paper by the same authors, "Response of Steel Moment and Braced Frames Subjected to Near-Source Pulse-Like Ground Motions by Including SoilStructure Interaction Effects" by Pooriya Ayough, Sara Mohamadi, Seyed Ali Haj Seiyed Taghia, Civil Engineering Journal (Vol. 3, No. 1, January, 2017, Page 15-34, http://civilejournal.org/index.php/cej/article/view/254/pdf. One of the conditions of submission of a paper for publication is that authors declare explicitly that the paper is not under consideration for publication elsewhere. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.