A Novel Framework to Assess Soil Structure Interaction (SSI) Effects with Equivalent Fixed-Based Models

This paper examines the effects of soil–structure and structure–soil–structure interactions in the design of foundations for adjacent concrete buildings, which are located on soft soils. The study employs an elasto-plastic model through static (quasi-dynamic) analysis using the direct finite element method by applying earthquake loads in one time step. Two concrete buildings, one with 6 stories and another with 12 stories, were modelled and numerically analysed using ANSYS. The foundations of these two buildings were analysed separately and compared when they were assumed to be adjacent to each other. The designs of the buildings’ foundations were evaluated independently and in comparison with each other to determine the impact of these interactions. The results indicated that accounting for the effects of both interactions increases the total deformation of the foundations. Additionally, the study found that adjusting the subgrade reaction modulus values (Ks) for different sections of the foundation can be a practical method to address both interaction effects simultaneously. This method also optimizes the weight of reinforcement material (Wr) by reducing it by 15% and modifying the positions and quantities of reinforcements used and considering various subgrade reaction modulus values in foundation design.

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Role of the Subgrade Reaction Modulus in the Design of Foundations for Adjacent Buildings

Khosravifardshirazi,

Tavana,

Javadi

et al. 2024

“…Using Equation (11) and applying the boundary conditions, the value of c 3 is determined as follows:…”

Section: Moment Contribution Ratio For Triangle Static Loadmentioning

confidence: 99%

A Method for Determination of Moment Contribution Ratio under Foundation Rotation in Shear Wall-Frame Systems

Bozdogan,

Keskin

2024

In shear wall-frame systems, the foundation rotation that may occur under the shear walls changes the displacements and interstory drift ratios and changes the internal force distribution. This study investigates the effect of foundation rotations under shear walls on internal force distribution in shear-frame systems. The originality of the study lies in considering parabolic loads and dynamic analysis (first mode), in addition to static uniform or triangular distributed loads, when determining the shear wall moment contribution ratio under the influence of foundation rotation. The shear wall contribution ratio, a key parameter in many earthquake codes, is defined as the ratio of the sum of bending moments taken by the shear walls at the base to the overturning moment. It plays a crucial role in determining the building’s behavior. Depending on this ratio, the load-reduction coefficient is changed. This study investigates the effect of foundation rotation on the moment distribution at the base for three different static load cases and the first mode in the dynamic analysis. The multi-story building is modeled as an equivalent sandwich beam. The moment contribution ratio (MCR) was calculated with the help of analytical solutions of the differential equations written for three different load cases in static conditions, and graphs were created for practical use directly calculating the MCR. In the methodology of the study, the initial step involves the calculation of the equivalent sandwich beam stiffness parameters and the foundational rotational spring. Subsequent to these calculations, the MCR values can be directly obtained with the help of graphs. This approach facilitates the rapid and practical determination of the MCR and can be used in the preliminary sizing phase to eliminate possible errors in the data entry of software that performs detailed analysis. In addition, in the presented study, it has been shown that taking a single mode into account is sufficient when calculating MCR values in dynamic analysis.

“…Soil bases can be modelled using both nonlinear elements of the Link type and elastic elements of the Spring type [20]. Some modelling approaches use GAP elements or alternative options [21,22].…”

Section: Taking Account Of Soil-structure Interactionmentioning

confidence: 99%

Ensuring the Safety of Steel Moment Frames Subjected to Uncertain Impacts

Alekseytsev

2023

The article addresses the problem of safety evaluation of steel moment frames of civil buildings, e.g., warehouses, shops, garages, and multistory industrial buildings on deformable soil in the relevant case of an emergency impact. The case of accidental emergency impacts is considered when such parameters as the point, direction, and intensity of an impact cannot be predetermined. Such impacts are not expected to trigger the progressive collapse of currently implemented design solutions and the whole structure must maintain the property of survivability. To evaluate this property, several calculations are to be made in the quasi-static statement to identify the stress–strain state under the most dangerous accidental impacts. Further, final calculations are to be made in the dynamic statement. In this case, the problem of search is solved using the criterion of minimizing the integral safety margin of structural elements in a steel moment frame design. Calculations prevent the frame stability loss. The calculation is performed in the quasi-static statement using models made in compliance with the deformation theory of plasticity, while the calculation in the dynamic statement takes into account the associated plastic flow rule. The proposed procedures allow for designing steel moment frames that are resistant to accidental emergency impacts. Impact loading is analysed as pulse loading, which is statically equivalent to the dynamic effect of an inelastic impact of a stiff body on a structural system. The design and the efficiency evaluation of a steel moment frame of a two-story building are considered.