Foundation Beam Research Articles

Experimental investigation on shear fatigue behavior of perfobond strip connectors made of high strength steel and ultra-high performance concrete

This paper explores the fatigue performance of perfobond strip connectors (PBL) made from high-strength steel (HSS) and ultra-high performance concrete (UHPC) by fabricating and testing eight push-out specimens. The failure modes, load-slip curves, stiffness degradation, and residual strength of the PBLs are presented and discussed. The experimental results show that fatigue loads caused connector’s crack formation and stiffness degradation, leading to concrete dowel shear fracture and transeverse rebar bending-shear rupture damage. Compared to the static performance, the fatigue residual strength of the PBL subjected to 0.5 × 106, 1.25 × 106, and 2.0 × 106 loading cycles decreases by 1.2 %, 3.6 %, and 14.5 %, respectively, with corresponding reductions in ductility of 14.7 %, 19.4 %, and 4.7 %. Under the same loading cycles, the fatigue residual strength and ductility of the PBL with a maximum repeated load of 0.65Pu are 13.0 % and 3.9 %, respectively, smaller than those of 0.55Pu. A semi-empirical model based on the elastic foundation beam theory and linear cumulative damage model is developed to predict the residual strength of the PBLs using HSS and UHPC. The accuracy and applicability of the model are calibrated using the experimental results. The findings of this study can serve as an experimental foundation and theoretical reference for the fatigue design of PBLs made with high-strength materials.

Research on cutting mode and thrust force of major cutting edge for drilling CFRP composite plates based on viscoelastic mechanics and foundation beam theory

Research on cutting mode and thrust force of major cutting edge for drilling CFRP composite plates based on viscoelastic mechanics and foundation beam theory

Analysis of the underlying shield tunnel deformation caused by a newly built channel

As the development of underground space progresses, newly constructed waterways inevitably intersect with existing tunnels, posing significant challenges to the safety of underlying tunnels and making deformation control a critical issue in engineering design and construction. This study investigates the impact of waterway foundation pit excavation on the deformation of underlying tunnels. The research considers not only the vertical unloading at the bottom of the pit but also the horizontal unloading from the four side walls, which induces additional vertical stress fields in the underlying soil. These additional stresses are applied to the tunnel structure, modeled as a Pasternak elastic foundation beam, and the vertical tunnel deformation due to excavation unloading is calculated using the finite difference method. To validate the analytical results, a three-dimensional numerical model is employed. Furthermore, the study analyzes deformation trends under varying excavation sizes and the relative positions of the foundation pit and tunnel. The findings demonstrate that the proposed method provides a highly accurate, cost-effective, and efficient solution for predicting tunnel deformation during the excavation of small foundation pits. This research offers valuable insights for the design and assessment of underground structures in urban environments.

Diseño estructural del edificio más alto de El Salvador

The Corporate Tower is a 33-story building with a total height of 139m and a floor area of 81x56m. The structural systems used were Dual Frame-wall and Special Moment Frame systems with Seismic Detailing, the foundations were of the deep type consisting of interconnected concrete piles through foundation beams and pile caps. This article outlines the guidelines followed for the superstructure and substructure’s structural design, as well as the challenges overcome due to the unique conditions of the project. Given the significance of this endeavor, site response studies were necessary to optimize the structure. Similarly, state of the art standards were implemented in accordance with the latest developments in structural design, such as ASCE7-10 and ACI318-14. ILIA: Investigaciones Latinoamericanas en Ingeniería y Arquitectura, No. 01, 2024: 115-121.

Optimalisasi Desain Struktur Gedung Interdisciplinary Engineering (IDE) – Fakultas Teknik Universitas Indonesia dengan Memanfaatkan BIM (Building Information Modelling)

Project design is a step in the construction process that determines the technical requirements to be applied when the project is constructed. BIM (Building Information Modeling) is a form of technological innovation used in project design. BIM (Building Information Modeling) has become the main factor for increasing efficiency and accuracy; using BIM, everything related to design, construction, scheduling, and costs can be integrated into one digital platform that all stakeholders can access. In this paper, the structural planning optimization of the Interdisciplinary Engineering (IDE) Building - Faculty of Engineering, University of Indonesia, will be carried out. This building planning refers to (SNI-2847-2019) concerning Structural Concrete Requirements for Buildings and (SNI-1726-2019) concerning Procedures for Planning for Earthquake Resistance of Structures. Outputs are generated through superstructure and substructure plans, the design of foundation structures, columns, beams, and plates, 2D Detail Engineering Design (DED), 3D modeling, and construction management plans in the form of Budget Plans and scheduling.

Subsidence Prediction Method Based on Elastic Foundation Beam and Equivalent Mining Height Theory and Its Application

Grouting technology in overburden separation is recognized as an effective method to prevent surface subsidence and reuse solid waste. This study used mechanical analysis to explore deflection characteristics of key strata and accurately predict and control surface subsidence. Conceptualizing the coal–rock mass beneath the key strata as an elastic foundation, we developed a method to calculate the elastic foundation coefficients for various regions and established an equation for key strata deflection, validated through discrete element numerical simulations. This simulation also examined subsidence behavior under different grout injection–extraction ratios. Additionally, combining the equivalent mining height theory with the probability integral method, we formulated a predictive model for surface subsidence during grouting. Applied to the 8006 working face of the Wuyang Coal Mine, this model was supported by numerical simulations and field data, which showed a maximum surface subsidence of 546 mm at a 33% injection–extraction ratio, closely matching the theoretical value of 557 mm and demonstrating a nominal error of 2%. Post-grouting, the surface tilt was reduced to below 3 mm/m, meeting regulatory standards and eliminating the need for ongoing surface structure maintenance. These results confirm the model’s effectiveness in forecasting and controlling surface subsidence with grouting. The study can provide a basis for determining the grouting injection–extraction ratios and evaluating the effectiveness of surface subsidence control in grouting into overburden separation projects.

A sandwich-type Winkler-Pasternak double elastic foundation beam model for analysis of nut column load transfer systems of shiplifts

The rack and pinion shiflifts feature its capability of fortification against extreme accidents of unbalance of ship chamber. This requires the load transfer systems of nut columns to be able to transfer the huge and centralized loads from the safety mechanisms to the tower columns in a distributive bearing way. Aiming at exploring a design-oriented computation method for the nut column load transfer systems (NCLTSs), a sandwich-type semi-infinite coupling Winkler-Pasternak double elastic foundation beam model (DEFBM) has been established, with a distributive assumption of the axial constrain force on the interfaces between the nut columns, mortar beds, adjusting beams and the second stage concrete based on the physical model test, has been proposed. A set of formulars for describing the distribution of deflections, internal forces and stress of nut columns and adjusting beams have been derived. A case study of the Three-Gorges shiplift has been conducted to demonstrate the approach of calculation of internal forces and stress by applying the formulas based on sandwich-type Winkler-Pasternak DEFBM, showing the convenience and rationality of the method to parametric layout design of the nut columns and adjusting beams in NCLTSs. Not only to NCLTSs and rack load transfer systems of shiplifts, the sandwich-type Winkler-Pasternak DEFBM also supplies the reference to the modeling and analysis of the rail-embedment structural systems broadly applied in hydraulic engineering.

Thermal buckling of organic nanobeams resting on viscous elastic foundation

This study presents an analytical solution for organic solar nanobeams by including the new high-order shear deformation theory and considering the impact of size effects using non-local elasticity theory. The beam is supported by a viscoelastic base and experiences thermal loads that are distributed in accordance with uniform and nonlinear principles. The calculation formulae are derived from the consideration of significant deformations in the beam, resulting in increased complexity of the calculations. The equilibrium equation is derived from the fundamental principle of maximum work potential. The explicit equation for the critical thermal load is derived, providing a convenient means for the calculation and analysis of the impacts of relevant factors. The critical thermal buckling load encompasses both real and imaginary components, with the real component corresponding to the thermal load responsible for inducing beam instability, and the imaginary component associated with the dissipation of this load. This consideration is particularly pertinent when accounting for the foundation resistance. This finding enhances the level of interest in the research outcomes. This study also examined the impact of certain characteristic factors of the foundation and organic beams on the thermal buckling behavior of the beam, establishing a scientific basis for practical design applications.

Analysis of the effect of nonlocal factors on the vibration of nanobeams

Abstract Currently, the Eluer-Bernoulli beam nonlocal theory does not fully consider the effects of foundation deformation and axial force on the beams, and cannot accurately reflect the real mechanical properties of nanobeams. The primary objective of this study is to introduce a novel computational method designed for an enhanced characterization of the vibrational behavior of nano beams. Initially, this method incorporates the influence of foundation deformation on beam bending, accounts for the effects of axial forces, integrates Eringen's nonlocal theory, and establishes a modified Euler-Bernoulli beam theory model for the first time, accompanied by a degradation validation of the model. Subsequently, the Laplace transform and Hasselman's complex mode synthesis method are utilized to solve the model, providing the first derivation of the state-space transfer function for the nano beam vibration model based on the modified Euler-Bernoulli beam theory that includes axial force effects. Lastly, the study elucidates the impact of nonlocal factors and various parameters on the vibration characteristics of nanobeams. The results show that the order n increases, and the peak frequency value moves in the direction where the nonlocal factor tends to zero. When the order n is less than 6, the frequency peak is mainly concentrated in the interval where the nonlocal factor is greater than 0 and less than 0.1. At the same order, the beam length increases, and the peak frequency moves in the direction of increasing non-local factor. The modified geometric parameters and the foundation beam stiffness parameters have a greater effect on the peak of the beam's vibration mode in the higher order case and a lesser effect in the lower order case. The larger the nonlocal factor, the larger the peak of the vibration mode. The foundation beam stiffness parameter also has an effect on the direction of the peak vibration mode at the 1st and 2nd orders. The research results will help to predict the vibration behavior of nano beams under different conditions more accurately and provide an important reference for related applications.

Life Cycle Assessment of Additively Manufactured Foundations for Ultratall Wind Turbine Towers

ABSTRACTWind energy production is rapidly growing in the United States and is expected to continue increasing as more and larger wind turbines are installed. To support these taller and heavier onshore turbines, new foundations must be designed and manufactured. One proposed method of reducing the total amount of concrete and steel in spread foundations is to utilize additive manufacturing to enable more material‐efficient designs. To compare these additively manufacturing‐enabled designs to conventional foundation designs, this study performs a life cycle impact assessment of four ultra‐tall wind turbine foundations: two foundations using 78‐MPa 3D printed stay‐in‐place concrete formwork cast with 35‐MPa ready‐mix concrete with reinforcements, and two conventional foundations cast entirely out of 35‐MPa concrete with reinforcements. The life cycle assessment investigates the environmental impacts of four different stages, including materials production, transportation, construction, and end‐of‐life. The materials production stage is found to dominate the life cycle results, contributing over 97% of the total CO2 emissions and over 88% of the fossil fuel depletion for each foundation. Compared to the conventional designs, the Short Flat Ribbed Beam foundation with 3D printed formwork has 22.4% lower CO2 emissions and 28.3% lower fossil fuel depletion than the Circular foundation, and 2.0% higher CO2 and 5.9% lower fossil fuel depletion compared to the Tapered foundation. Parametric studies indicate that reducing cement content and increasing recycled content in printed concrete can significantly reduce the overall life cycle impacts of the foundations.

Analytical Solution for Longitudinal Seismic Responses of Circular Tunnel Crossing Fault Zone

ABSTRACTThis paper proposes a simplified analytical solution for longitudinal seismic responses of a circular tunnel crossing a fault zone under longitudinally propagating shear waves. The transmissions and reflections of shear waves at two geological interfaces between the fault zone and intact rock are considered when calculating the free‐field displacement. An improved elastic foundation beam model considering different tangential contact conditions at the tunnel‒rock interface is also adopted. According to the continuous conditions at the two geological interfaces, explicit expressions for the tunnel displacement, bending moment, and shearing force are given. The effectiveness of the proposed analytical solution is validated via numerical simulations, and the importance of accounting for tangential contact conditions at the tunnel‒rock interface is emphasized. Moreover, parametric studies are performed to investigate the effects of the fault zone width, rock conditions, tunnel lining stiffness, tangential contact conditions, and earthquake frequency on the deformation and internal forces of tunnels subjected to seismic waves. This novel analytical solution can be utilized to quickly estimate the longitudinal seismic responses of circular tunnels crossing fault zones subjected to longitudinally propagating shear waves, particularly in the preliminary engineering design, and can be extended to geological conditions with multiple interfaces.

Shear behavior of multi-row perforated GFRP rib shear connectors in GFRP-concrete hybrid beams/desks

Perforated GFRP ribs (PFRs) and epoxy bonding are commonly used shear connections ensuring a full composite action in FRP-concrete hybrid beam/deck. This study demonstrates test results of 27 push-out specimens to compare the failure modes, shear load-slip (P-S) curves, and shear performance of PFRs and epoxy bonding. The variables included the sanding depth on GFRP profiles (0.5 mm/1.0 mm) and the rows of PFRs (1/2/3/5). The push-out tests highlighted that the PFR specimens with 0.5 mm or 1.0 mm sanding depth experienced interface debonding failure and shearing failure of PFR, respectively. The epoxy bonding specimens with 0.5 mm or 1.0 mm sanding depth suffered adhesive failure and cohesive failure, respectively. Increasing the sanding depth from 0.5 mm to 1.0 mm is an effective approach to prevent the debonding failure. The typical shear load-slip (P-S) curves for PFRs exhibit the micro-slipping stage (slip≤0.2 mm) and the slipping stage (slip>0.2 mm). The P-S curves of epoxy bonding showed only the elastic stage. The shear capacity of the double-row PFR connector was close to epoxy bonding. The shear capacity and stiffness of the PFRs increased 37.2∼47.3 % and 99.7∼119.7 % with the sanding depth improved from 0.5 mm to 1.0 mm, respectively. Increasing the sanding depth would improve the shear stiffness of epoxy bonding. The shear capacity and stiffness of PFRs decreased with the rows of PFRs increased. Calculation equations for the shear capacity of epoxy bonding and PFRs were evaluated by comparing the test results collected from the literature and calculated results. Based on the elastic foundation beam theory, a calculation equation for the shear stiffness of PFRs was proposed and a theoretical bi-linear model was suggested to predict the load-slip curves.

Theoretical investigation on vibration reduction characteristics of a novel foundation metaconcrete beam

The issue of low-frequency vibration problems in foundation beams is becoming increasingly serious. Therefore, it is imperative to find new methods for effectively reducing and controlling these low-frequency vibrations. This study proposes a novel foundation metaconcrete beam to address the challenge of low-frequency vibrations based on locally resonance theory. Additionally, an improved transfer matrix method (ITMM) is proposed to quickly and effectively calculate the bandgap of foundation metaconcrete beam. The validity of the ITMM is verified through the plane wave expansion method (PWEM), and transmission characteristics are fully analyzed using the spectral element method (SEM). Furthermore, the influences of geometric and material parameters of the foundation metaconcrete beam on band structures and transmission functions are investigated in detail. The results show that the proposed foundation metaconcrete beam exhibits multiple bandgaps, and can effectively attenuate low-frequency vibrations. These bandgaps can be tailored by appropriately adjusting relevant parameters. The foundation properties determine the formation of the first bandgap, the damping ratio of the resonator has double effects on band structures, the mass ratio of the resonator is crucial in adjusting these bandgaps, and the axial force can adjust the attenuation capability of the first bandgap.

Slip modulus of inclined screw connectors in glued laminated bamboo and wood-concrete composite beams

ABSTRACT The existing research has predominantly focused on the shear behavior of inclined screws in wood-concrete composite beams. However, there is a significant research gap regarding the slip modulus of inclined screw connectors in glued laminated bamboo and wood (GLBW)-concrete composite beam. To address this gap, nine groups of shear tests were performed to study the load-slip behavior of inclined screw connectors in GLBW-concrete composite beams. This study analyzed the impacts of screw embedding length, screw diameter, screw embedding angle, and bamboo board thickness on the slip modulus of inclined screw connectors. The results showed that in comparison to inclined screw connectors with a 90 mm embedding length, the slip modulus of screw connectors with 110 and 130 mm embedding lengths increased by 11% and 19%, respectively. As the screw embedding angle decreased, the slip modulus of inclined screw connectors increased. For bamboo thicknesses of 30, 60, and 300 mm, the slip modulus of inclined screws was improved by 40%, 78%, and 89%, respectively, compared to the screws in pure wood beam. This study presented an analytical model for predicting the slip modulus of inclined screws in GLBW-concrete composite beam based on the layering method and elastic foundation beam theory.

Theoretical analysis of the mechanical response of a lined canal induced by soil frost heave behavior based on improved foundation beam models

Lined canals in cold regions often experience severe frost damage, posing a significant threat to the water supply safety. This paper proposes a modified analytical solution for the response of canal lining under soil frost heave, which is based on a Timoshenko beam on a Pasternak foundation considering tangential contact between the lining and frozen soil. This analytical solution can provide any solution using Timoshenko or Euler–Bernoulli beams on Pasternak or Winkler foundations with or without tangential contact. Then, the modified analytical solution, along with the traditional analytical solutions using Euler–Bernoulli beams on Winkle foundations, is compared against both model test and numerical simulation results. The modified analytical solution performs better than the traditional solution. Finally, the effects of foundation model, beam model, and tangential contact in simulating canal frost heave were discussed, and some measures to mitigate canal frost heave are proposed. The results show that solutions based on Winkler foundation overestimate frost heaves and tensile stresses of canal linings, and solutions without considering tangential contact only obtains overestimated frost heave. In addition, solutions based on Euler–Bernoulli beams underestimate frost heaves slightly and overestimate tensile stresses slightly. Therefore, the Pasternak foundation, Euler–Bernoulli beam, and tangential contact model can be used to simulate canal frost heave. The modified analytical solution directly uses field measurements of soil free frost heave to calculate canal frost heave, thereby enhancing result reliability. This analytical solution provides a simple method for canal frost heave design, and can be applied to frost heave analyses of flat and inclined structures.

Improved calculation method for corresponding characteristics of foundation pit excavation on the diaphragm wall

The excavation of the pit causes displacement of the surrounding soil, and the excessive deformation causes damage to the existing support structure, which in turn affects the safety of the pit. Reasonable calculation of structural deformation and internal force is crucial for design and construction. Most of the existing theoretical methods simplify the diaphragm wall(DW) as an Euler-Bernoulli beam acting on the Winkler foundation, consider beam-soil interaction, and simplify the soil as isotropic and continuous. However, the shear effects due to the differential deformation of the structure, the unloading stresses acting on the structure due to foundation excavation, and the discontinuous nature of the multilayered soil are neglected. In this paper, an improved analysis method is proposed based on the elastic foundation beam theory. The DW is simplified as a Timoshenko beam and the foundation is simplified as a Vlasov two-parameter model, and a proposed model considering the shear effect of the DW and the interaction of adjacent springs is established, and the proposed method for the deformation and internal force of the DW is obtained by the finite-difference method. The correctness and applicability of the proposed method are verified by numerical simulation and field monitoring data. The effects of equivalent bending stiffness, equivalent shear stiffness, soil elastic modulus, and excavation depth on the deformation and internal force of the DW were further analyzed. The results show that the proposed method can accurately solve the deformation and internal force of the DW, and the maximum errors between the proposed method and the numerical simulation results are only 4.5 % and 1.3 %, respectively. The equivalent bending stiffness of the DW and the elastic modulus of the soil have more significant effects on the horizontal deformation and internal force. The excavation depth is more sensitive to the deformation of the DW, and there is an exponential decay trend between the two. When the equivalent shear and bending stiffnesses reach 6.8×107 kN·m2 and 2.9×107 kN/m, the effect on the horizontal deformation is no longer obvious. The proposed method in this paper can accurately calculate the internal force and deformation of the DW.

Simplified Modeling Method for Prefabricated Shear Walls Considering Sleeve Grouting Defects

The sleeve grouting connection is the most common form of vertical connection for prefabricated shear walls. However, during construction, this type of connection is prone to defects such as insufficient anchorage length of reinforcement, deviation of reinforcement, and insufficient amount of sleeve grouting, which significantly impact the integrity and seismic performance of the prefabricated shear wall structure. The finite element analysis of the prefabricated shear wall with sleeve grouting connection is still based on solid element modeling. This method has the disadvantages of complex models and low computational efficiency. In this paper, a simplified modeling method for prefabricated shear walls considering sleeve grouting defects was proposed to address this issue. Firstly, the equivalent constitutive relationship of the sleeve grouting defect connector was constructed based on the uniaxial tensile test of the existing sleeve grouting defect connector, and the T3D2 element was used to simulate the sleeve grouting connector. Then, the mechanical behavior of the horizontal joint between the shear wall and the foundation beam was simulated by the cohesive force model, and the prefabricated shear wall models with sleeve grouting defects were established. The accuracy of the simplified modeling method was verified by comparing the experimental results and numerical simulation results of the seismic performance of the prefabricated shear wall with sleeve grouting defects. The results showed that the hysteresis curve, skeleton curve, and failure mode of the numerical simulation were in good agreement with the test results. However, the stiffness of the concrete degenerated rapidly due to the apparent development of plastic-damaged concrete, which made the falling section of the hysteresis curve of the numerical simulation different from that of the test. The proposed simplified modeling method can be further applied to the performance study of prefabricated shear walls with sleeve grouting defects and can provide a reference for structural performance evaluation, design optimization, and construction quality control to a certain extent.

Study on the Impact of Deep Foundation Excavation of Reclaimed Land on the Deformation of Adjacent Subway Tunnels

The objective of this research is to investigate the characteristics of the deformation response in adjacent subway tunnels caused by deep foundation excavation of reclaimed land. Focusing on a deep foundation excavation project situated in proximity to Line 11 of the subway in Shenzhen, this study employs theoretical analysis, numerical simulation, and on-site measurements to thoroughly investigate the deformation issues induced by the unloading of the excavation. The research results are as follows: using the energy method to calculate the uneven deformation of adjacent subway tunnels caused by the excavation can overcome the limitations of traditional algorithms, which treat the subway tunnel as a uniformly elastic foundation beam, resulting in more reasonable calculation results. Increasing the self-stiffness (EI)eq of the tunnel can effectively reduce the maximum displacement (wmax) of the tunnel, and as (EI)eq increases, its “weakening effect” on wmax gradually diminishes. Underground continuous walls can effectively control tunnel deformation, with tunnel displacement decreasing as the thickness and concrete strength of the continuous walls increase. “Long excavation” deep foundation excavations can impact the displacement and uplift range of the tunnel, with the maximum tunnel displacement showing a nonlinear decrease with increasing excavation depth. Tunnel displacement decreases as geotechnical parameters (elastic modulus E, internal friction angle φ, and cohesion C) increase, with the elastic modulus being the most sensitive parameter. The research findings can be applied to tunnel construction, maintenance, and safety evaluations, providing valuable references for similar engineering projects in the future.

A modified Nonlinear Foundation Beam model for half-rigid monopiles with Timoshenko representation and compatible soil springs in sand

There is a large number of monopile foundations for offshore wind turbines falling in the type of half-rigid pile, and are recommended to be analyzed by the p-y method in design. However, the p-y method currently adopted in oil and gas industry for slender piles has proved to be inapplicable for monopile-soil interaction, with overestimated ultimate lateral resistance and underestimated initial stiffness predicted. Thus, factoring in the bending resistance provided by shaft friction and end bearing forces for large diameter monopiles, a modified Nonlinear Foundation Beam (NFB) method is proposed in this paper to predict the monopile response in sand, where a beam element considering sectional shear stress is adopted, and another three sets of soil springs are incorporated with the p-y soil spring. Unified relationships of the proposed soil springs are also proposed with varying sand and pile properties. The modified NFB method is validated by published test results with diameters ranging from 2 m to 6 m, and L/D ratios from 5.08 to 8.29, proving its applicability for analysis of half-rigid monopiles.

Research on the Correction of Soil Pressure Distribution Pattern in Circular Working Wells in Soft Soil Areas

This paper investigates the distribution characteristics of earth pressure on circular caisson foundations in soft soil areas based on practical engineering considerations. Utilizing a three-dimensional numerical analysis model and a displacement-based method for earth pressure calculation, the lateral earth pressure on the retaining structure is examined. Adjustments are made to the distribution pattern of earth pressure on circular caisson foundations in soft soil areas. The study demonstrates that the radius of the caisson significantly influences the spatial distribution of soil pressure. Additionally, empirical formulas for the depth and radius of the reduction in soil pressure around circular caisson foundations are obtained through the research. Comparative analysis reveals that the modified earth pressure planar foundation beam method, which accounts for the arching effect, is simpler, features more mature parameter selection, and is more cost-effective than the three-dimensional finite element method. In comparison to the standard planar elastic foundation beam method for earth pressure, it aligns more closely with the actual direction of displacement.