Peak Bending Moment Research Articles

Effect of increased running speed and weight carriage on peak and cumulative tibial loading.

Tibial stress injuries are a burdensome injury among military recruits. Military activities include running and the carriage of additional weight, and this may be related to the high risk of bone stress injuries. The aim of this study was to quantify tibial loading when running at two different speeds, with and without additional weight, and to quantify their combined influence. Fourteen male distance runners who ran at least 40 km per week ran barefoot on a force-instrumented treadmill in four conditions representing preferred running speed (mean (SD) 3.1 (0.3) m/s) and 20% increased running speed (3.8 (0.4) m/s), with and without 20% of body weight carried in a weight vest. Kinematics and kinetics were synchronously collected. Bending moments were estimated about the medial-lateral axis of the tibial centroid located 1/3rd of the length from distal to proximal. Static equilibrium was ensured at each 1% of stance. Peak bending moments were obtained in addition to cumulative-weighted loading, where weighted loading accounted for the relative importance of the magnitude of the bending moment and the quantity of loading using a bone-dependent weighting factor. There were no interaction effects for running speed and weight carriage on peak or cumulative tibial loading. Running at a 20% faster speed increased peak and cumulative loading per kilometer by 8.0% (p < 0.001) and 4.8% (p < 0.001), respectively. Carriage of an additional 20% of body weight increased peak and cumulative loading per kilometer by 6.6% (p < 0.001) and 8.5% (p < 0.001), respectively. Increasing the physical demand of running by increasing speed or weight carriage increased peak tibial loading and cumulative tibial loading per kilometer, and this may increase the risk of tibial stress injury. Running speed and weight carriage independently influenced tibial loading.

A corrugated steel fender for bridge pier protection against truck collision

This study proposes a novel corrugated steel fender system to protect bridge piers against truck collisions. In particular, the impact energy is mainly absorbed through the deformation of corrugated steel webs in the fender. Pendulum impact tests are conducted to demonstrate the benefits of installing the corrugated steel web to increase the fender stiffness, engage more lateral displacement, and dissipate considerable impact energy. Advanced finite element (FE) models are established using the software LS-DYNA and verified against experimental results of the pendulum impact test. Modeling considerations are implemented into developing a high-resolution FE model to simulate full-scale truck–fender–bridge collisions, which discloses the fender’s effectiveness in protecting the bridge pier. The proposed fender system can mitigate the post-impact damage to the bridge pier by reducing its peak impact force, lateral displacement, and bending moment at the base. Moreover, parametric analyses are performed to investigate the effects of different fender design variables on the peak impact force and absorbed impact energy. Among various design parameters, the thicknesses of the corrugated steel web and surface steel plate are the predominant ones. Finally, an optimal fender design criteria is proposed to simultaneously minimize the impact damage to the bridge pier and the truck.

Study on Seismic Performance Optimization of Assembly Concrete-Filled Steel Tubular (CFST)-Laced Piers

This study aims to investigate the seismic behavior of concrete-filled steel tubular (CFST)-laced piers; after verifying the model through engineering tests, the simplified finite element models (S-FEM) and refined ones (R-FEM) with CFST-laced piers are developed in this manuscript, respectively. Through comparison, it is found that the S-FEM can effectively improve analyzing efficiency while meeting the requirements of engineering analysis accuracy. In addition, the seismic response of assembled flange-connected CFST-laced piers bridge was studied based on the S-FEM, and different structural parameters, including pier height, axial compression ratios, steel ratios of CFST columns, steel lacing tube arrangement, and longitudinal slope, are considered to optimize the bridge design scheme. Results indicate that the parameters of 0.1 axial pressure ratios and 1:30 longitudinal slope show superior seismic performance. Meanwhile, the peak axial force and peak bending moment of CFST column limbs occur at the pier bottom, and the flanges, which are subject to larger bending moments, are generally located at the two connection positions above the pier bottom.

Experimental study on dynamic response of pile-supported wharf under wave and ship berthing collision

Pile-supported wharf is widely used in deep-water port engineering, which is inevitably subject to joint action of wave and ship berthing collision in marine environment. The evaluation of dynamic response of pile-supported wharf under wave and berthing collision is particularly essential for the design of deep-water port infrastructures. In this study, a wave flume experiment was carried out to investigate the dynamic response of pile-supported wharf embedded in a saturated sand stratum under a given wave and a three-stage pendulum steel ball collision. The pendulum collision was applied at the corner and edge midpoint of the wharf deck, respectively. A variety of representative responses are explored, including time histories of acceleration, displacement, hydrodynamic pressure, pore water pressure, and strain, which characterize the important aspects of dynamic behavior of pile-supported wharf-ground system. Acceleration and displacement of deck as well as acceleration of sand stratum are dominated by the berthing collision; hydrodynamic pressure on piles and pore water pressure of sand stratum are controlled by the wave action; and strain and bending moment on piles are depended on the joint action of wave and collision. It should be noted that dynamic response characteristics of pile-supported wharf will change significantly due to the decreasing of pile effective buried depth near berths induced by the berthing collision energy accumulation. Furthermore, pile group effects including wave scour around piles, collision energy propagation in a sand stratum, and peak bending moment on piles are explored. For comparison, dynamic response of a single pile-ground system and free field are also discussed. Dynamic response of sand stratum around single pile induced by berthing collision on wharf deck is greater than that of free field at the same distance. Experiment techniques and insights from this study may be of significance to the design and maintenance of pile-supported wharves.

Seismic protection of land-based wind turbine towers using the tuned inerter damper

The tuned inerter damper (TID) has recently emerged in the literature as a bona fide resonant vibration absorber for the seismic protection of building structures by relaxing the requirement for large secondary mass employed in conventional tuned mass dampers (TMDs). This is achieved by leveraging the inertia property of lightweight inerter devices, called inertance. This paper extends the application of the TID to address the seismic response reduction of the supporting towers of land-based wind turbines (WTs). To this aim, a novel vibration suppression strategy is proposed for WT towers in which a TID is attached at two different locations inside and along the height of the tower and is tuned to the tower’s dominant natural frequency. Numerical assessment is supported by developing a finite-element model of the benchmark NREL 5 MW WT equipped with an ad hoc TID model placed at different locations in the tower and with different inertance values. The assessment includes time-domain response history analyses for 28 earthquake ground motions (GMs) with and without pulses under concurrent thrust wind forces for 4 different mean wind speeds. Improved TID vibration suppression performance is noted by installing the TID closer to the tower top and by increasing the inertance and/or the distance of the attachment locations. Further, the TID achieves significant reductions of tower top peak displacement and acceleration as well as peak base shear and bending moment for all the different combinations of GMs and wind speeds, outperforming a conventional TMD with 5% secondary mass ratio placed in the nacelle.

Speed and surface steepness affect internal tibial loading during running

BackgroundInternal tibial loading is influenced by modifiable factors with implications for the risk of stress injury. Runners encounter varied surface steepness (gradients) when running outdoors and may adapt their speed according to the gradient. This study aimed to quantify tibial bending moments and stress at the anterior and posterior peripheries when running at different speeds on surfaces of different gradients. MethodsTwenty recreational runners ran on a treadmill at 3 different speeds (2.5 m/s, 3.0 m/s, and 3.5 m/s) and gradients (level: 0%; uphill: +5%, +10%, and +15%; downhill: –5%, –10%, and –15%). Force and marker data were collected synchronously throughout. Bending moments were estimated at the distal third centroid of the tibia about the medial–lateral axis by ensuring static equilibrium at each 1% of stance. Stress was derived from bending moments at the anterior and posterior peripheries by modeling the tibia as a hollow ellipse. Two-way repeated-measures analysis of variance were conducted using both functional and discrete statistical analyses. ResultsThere were significant main effects for running speed and gradient on peak bending moments and peak anterior and posterior stress. Higher running speeds resulted in greater tibial loading. Running uphill at +10% and +15% resulted in greater tibial loading than level running. Running downhill at –10% and –15% resulted in reduced tibial loading compared to level running. There was no difference between +5% or –5% and level running. ConclusionRunning at faster speeds and uphill on gradients ≥+10% increased internal tibial loading, whereas slower running and downhill running on gradients ≥–10% reduced internal loading. Adapting running speed according to the gradient could be a protective mechanism, providing runners with a strategy to minimize the risk of tibial stress injuries.

Seismic behaviour of I-beams bolted CFST column connection using extended TSOBs

In this paper, the structural response and design method of Extended T-head Square-neck One-side Bolts (Extended TSOBs) bolted I-beams to Concrete Filled Steel Tubular (CFST) column cruciform connection were investigated under cyclic load through experimental, numerical, and theoretical approaches. The study mainly reports the effects of H-steel stiffener on seismic performance indices such as failure mode, bending bearing capacity, strength and rigidity degradations, and energy dissipation of the connection. Test results show that: (1) The H-steel stiffener can prevent Extended TSOB pull-out failure, but the relative slippage between the upper and lower columns is introduced in the strengthened connection; (2) The H-steel stiffener improves the peak bending moment, ultimate rotation, and accumulated energy dissipation of the connection by 3.3 %∼8.3 %, 33.9 %∼63.1 %, and 100.3 %, respectively; (3) The test connections can be classified as semi-rigid and partial strength joints according to Eurocode 4. The Finite Element Model (FEM) parametric analysis results show that Extended TSOB can be replaced by TSOB in the connections with H-steel stiffener and increasing the concrete grade has little effect on improving the connection bending bearing capacity. Moreover, two analysis models for calculating the bending bearing capacity of Extended TSOBs bolted I-beams to CFST column cruciform connections are proposed based on theory and tests. The accuracy and reliability of the proposed models are verified by comparing the calculated and tested bearing capacities.

Swelling and collapse behavior of expansive marl and its implications in foundation engineering

Expansive soils increase their volume upon wetting, but under high vertical stresses may exhibit collapse, with the latter aspect being rather overlooked in foundation engineering. Oedometer swelling/collapse tests on expansive Pliocene marls of various calcium carbonate content and plasticity index sampled from Nicosia, Cyprus, indicate that, unlike the free swelling strain, the swelling pressure is rather insensitive to the initial degree of saturation. Consequently, significant collapse strains upon wetting are not unlikely to occur in practical situations. The paper discusses the implications of this behavior in the case of shallow foundations and proposes methods of analysis. Under certain conditions, foundation design based on settlement calculations that use as input the fully saturated soil properties may be unconservative and supported structures may be exposed to severe risk of damage. For the design of mat foundations, stepwise distributions of the equivalent modulus of subgrade reaction across the mat as a function of the average bearing pressure are proposed based on the results of coupled finite element simulations. These distributions allow prediction of the peak bending moments produced at the end of the wet and dry seasons due to ground swelling and shrinkage, respectively, for the climatic conditions of Cyprus.

Field tests of rock-socketed monopile in coastal area subjected to lateral cyclic loading

Field tests were carried out to study the lateral cyclic loading characteristics of rock-socketed monopile in coastal area, and the variation law of pile body accumulative displacement, unloading stiffness, and pile body bending moment with the cyclic number and cyclic loading amplitude were obtained by actual measurement. Test results show that the cyclic loading history with sa small amplitude has a certain effect on the cyclic accumulative displacement and the degradation of unloading stiffness, and both the peak bending moment and locking moment of the pile body increase with the increase of cyclic numbers. By using the normalization method and formula fitting method, it is found that, the accumulative rate of cyclic displacement, the degradation rate of unloading stiffness, and the variation rate of peak bending moment of single piles in weathered rock layers are significantly smaller than those of sand foundation or clay foundation. The cyclic p-y curves at different depths are derived, and the different hysteretic characteristics between shallow cyclic p-y curve and deep cyclic p-y curve are explored. Finally, the static load test after cyclic tests was carried out, and it was found that the lateral bearing performance of the rock-socketed monopile was greatly degraded after a total of 3000 times of lateral cyclic loading.

Exact Winkler Solution for Laterally Loaded Piles in Inhomogeneous Soil

A novel exact analytical solution is derived for the equation y(4)+xny=0 in the region x≥0, which is important for the analysis of piles in soil with stiffness varying with depth. To date, exact solutions for long piles are available only for the cases where n=−4, 0, and 1. For other values of the exponent n, solutions have formerly been obtained numerically, mainly by the finite-difference method or approximate analytical solutions. An inherent difficulty in obtaining solutions for long beams (which are used to model flexible piles) lies in the inability to isolate the regular, converging part of the solution over the singular part that diverges with increasing x. In this paper, an exact solution is derived for n>−4, focusing on the important case of semi-infinite beams. Key aspects of the problem such as the stiffness and flexibility matrices at the pile head, and the peak bending moments due to eccentrically acting lateral loads, are discussed. A novel approach for deriving Winkler spring moduli for combined force and moment loading is proposed and shown to provide good agreement with rigorous numerical continuum results.

Effects of axial loading on dynamic response of laterally loaded single piles in liquefiable layered soil of Kolkata city considering nonlinearity of soil

In the present study, an advanced nonlinear finite-element based 3D numerical study has been carried out to investigate the effects of axial loading on dynamic response of soil-pile system in liquefiable layered soil deposits of Kolkata city. An advanced soil constitutive law based on multi-yield surface plasticity model implemented in fully-coupled u-p formulation is adopted for soil-fluid interaction and pore water pressure development reasonably. The present model is validated with the past experimental results. Then, a detailed systematic parametric study is performed for numerical simulation of pile failures in layered soil deposit under axial loading by taking into account various soil conditions, pile and ground motion parameters. It is seen that the depth of liquefaction (DL) is decreased from 11.5 to 1.5 m adjacent to the pile when the axial load on pile increases from 0 to 1327 kN. Parametric studies also reveal that the bending moment response of pile under axial loading can be higher in non-liquefiable condition, with reference to the liquefiable condition. The peak lateral displacement decreases by 83.2% in non-liquefiable condition and 60.71% in liquefiable condition due to decrease of axial load from 1327 to 0 kN. Also, peak bending moment developed in the pile decreases by 97.2% in non-liquefiable condition and 82.7% in liquefiable condition when the axial load reduces from 1327 to 0 kN. So, the designer should be considered both extreme scenarios for safe and economical design. Also, it is noticed that the buckling capacity of pile is improved significantly by using larger diameter pile and the bending capacity is increased by selecting higher grade of concrete. It is concluded that the bending and buckling failure mode may be avoided by selecting a suitable combination of material strength and pile geometry.

Research on key joint and test platform of high-payload transporter for tokamak

The high-payload transporter is a key part of the multipurpose deployer, which is important for realizing the remote handling of tokamaks. This paper presents an analysis of the key joint between the high-payload transporter and the design of the test platform. The kinematic, structural, and load characteristics of the main joints of a heavy-duty manipulator were analyzed according to the peculiarity of high precision, large length, and heavy load of the high-payload transporter. Joint No. 4 (J4) was determined to be the key joint of the high-payload transporter. The peak torque, bending moment, and shear force of J4 under working conditions and seismic conditions were determined via numerical simulations. The functions and key technical parameters of the test platform for J4 were determined according to the test analysis results and numerical simulation. The structure of the test platform was designed, and its working principle was described.

Research on the Pounding Response and Pounding Effect of a Continuous Rigid-Frame Bridge with Fabricated Super-High Piers Connected by Grouting Sleeves

The dynamic characteristics of a continuous rigid-frame bridge with fabricated super-high piers (CRFB-FSP) connected by grouting sleeves and adjacent continuous beam bridges (AB) are significantly different, and they are prone to pounding under earthquake excitation. At present, the pounding response between the CRFB-FSP and AB is still unclear, and the impact of the pounding on the seismic performance of a CRFB-FSP is still in the exploratory stage. In this study, two 1/20 scaled models of a CRFB-FSP (MB) and a cast-in-place AB were designed and manufactured. Then, according to the research purpose and the output performance of the shaking table, three each of non-long-period (NLP) ground motions and near-fault pulse-type (NFPT) ground motions were selected as the inputs of the excitation shaking table test. The peak ground acceleration (PGA) changes from 0.5 g to 1.5 g. According to the similarity ratio (1/20), the initial gap between the MB and AB was taken as 7 mm (prototype design: 140 mm). Furthermore, the longitudinal pounding response between the CFRB-FSP and AB, as well as its influence on the seismic performance of the CFRB-FSP, was systematically investigated through a shaking table test and finite element analysis (FEA). The results showed that the pounding with the CRFB-FSP easily caused a persistent pounding, which may increase the damage risk of the pier. The peak pounding force under the NFPT ground motion was more significant than under the NLP ground motion, whereas the pounding number under the NFPT ground motion was smaller. The peak pounding force increased with the increase in the initial gap, pounding stiffness, span, and pier height. With and without pounding, the CRFB-FSP reflected higher-order mode participation (HMP) characteristics. After pounding, under the NFPT excitation, the HMP contribution increased significantly compared with that of the without pounding condition, while this effect under the NLP excitation was smaller. The peak displacement of the main beam of the CRFB-FSP increased with the increase in the main beam span, pier height and initial gap. The peak bending moment of the pier bottom increased with the increase in the main beam span and initial gap, however, decreased with the increase in the pier height. Moreover, the peak displacement of the main beam and the peak moment of the pier bottom of the CRFB-FSP both reduced. In contrast, the corresponding seismic response of the AB increased under the same conditions.

Research on the Stress Characteristics of Initial Tunnel Supports Based on Active Load Adjustment

Initial tunnel support takes on a critical significance in the stability control of surrounding rocks and the core content of tunnel support design. Its stability and safety are essential to the tunnel. The support load was optimized using the active surrounding rock load intervention scheme in accordance with the section form and bearing characteristics of the support structure. The optimization scheme of active surrounding rock load was obtained by applying active intervention load to the initial support of the tunnel to minimize the peak moment of the support structure. An active adjustment system for tunnel-surrounding rock loads was developed using the function of hydraulic load transfer and transmission combined with load proportion control. Based on the actual project, the implementation effect of the surrounding rock load active intervention scheme was verified by analyzing the measurement results of the supporting structure in the test section and the comparison section. The results suggest that the application of active intervention load can effectively improve the stress state of the tunnel initial support structure, significantly reduce the tunnel surrounding rock bias pressure and the structural peak bending moment, and increase the stability of the support structure. To control the peak moment of the supporting structure, an active intervention method and its implementation scheme for the stress of the tunnel supporting structure were proposed, which reduces the deficiency in which the conventional supporting structure can only passively bear the deformation pressure of the surrounding rock, effectively improves the stress state of the supporting structure, and can provide a reference for the development of novel tunnel supporting forms.

Theoretical and experimental study of the bending collapse of partially reinforced CFRP–Steel square tubes

Bending collapse of thin-walled steel tubes is a major energy absorption mechanism in lightweight structures, especially for crashworthiness. External composite reinforcements can increase the energy absorption and strength of steel tubes. However, to this date there are still difficulties to determine the maximum load and the collapse behavior of reinforced, multi-material shapes, e.g., steel shapes covered by CFRP. In this work, a theoretical analysis of the collapse of a partially reinforced CFRP–Steel tube is performed, which encompasses the calculation of both the peak bending moment and the bending collapse curve of tubes with either the flanges or webs with reinforcements. The theoretical approach is validated with three-point bending experimental tests and an adequate agreement with experiments is found. The results also show an important increase of up to 57% in the peak load and 45% in the specific energy absorbed for partially reinforced tubes, with a maximum 14% increase in weight, when compared with unreinforced tubes. The developed theoretical model enhances even further the existing bending collapse theories, as it incorporates reinforcements in the model and provides a powerful tool for engineering analyses, and can be implemented in concept models, and optimization algorithms with ease. These findings can be used for enhancing existing and new lightweight structures and improving the crashworthiness of several automotive structures.

Numerical investigation into impact responses of an offshore wind turbine jacket foundation subjected to ship collision

Offshore wind turbine structures are increasingly implemented but they could be largely exposed to ship collision in heavy maritime traffic area. This study aims to carry out a systematic parametric study on impact responses of the whole ship-offshore wind turbine jacket foundation system, thereby identifying the most dangerous impacting cases and vulnerable components. The three-point bending tests on DH-36 steel tubes designed by scaling jacket tubular members were performed. The effects of impact locations, collision angles and impact velocities on crashing responses, impact energy distributions and interactive deformation mechanisms were studied. Finally, the most dangerous impact cases and deformation were analyzed. It was showed that the bow impact on a leg tube resulted in the maximum local deformation of the leg and the maximum tower top displacement. The centric impact caused more severe local deformation than eccentric impact. And increasing the impact velocity from 0.5 to 3 m/s could increase the peak bending moment at the impact position of jacket leg. In the most dangerous location, the damage area and local indentation of the leg reached to 5.77 m2 and 916 mm (65.4% of diameter). The study can gain important insights into the development of crashworthy offshore wind turbine structures.

Study on Seismic Response Characteristics of Shield Tunnel in Soil‐Rock Combination Stratum

The sharp change of stiffness in the soil‐rock combination stratum is the weak point in the seismic design of the tunnel structure. To explore the influence of soil‐rock combination stratum vibration on the shield tunnel, the section of Jinan rail transit line 4 at the Olympic Sports Center is used as the research background. Firstly, the two‐dimensional numerical model is established, and the internal force calculation and distribution law of the structure are studied. Then, based on the third similarity theory, the model similarity physical relationship is derived. The shaking‐table model test of the soil‐rock‐structure system is carried out. The seismic response law of tunnel cross‐section is studied by the model test and numerical analysis. The results revealed the following: (1) the peak bending moment distribution diagram derived from numerical calculation is consistent with that obtained from the shaking‐table model test, which has shown that the numerical and experimental methods are correct, and the research results are available for the seismic resistance of shield tunnels. (2) The deformation, axial force, shear force, and bending moment of the tunnel structure in the soil‐rock combination stratum under the action of S‐wave change abruptly and significantly at the soil‐rock interface section, and the difference in structural stress between the upper and lower sides of the soil‐rock interface increased by 65.5%. The excessive stress difference changes the damage mode of the tunnel. (3) The relative difference and abrupt change of bending moment and shear force at the interface is more significant than the axial force, so that the tunnel structure at the soil‐rock interface is most prone to bending‐shear damage.

Experimental investigation on monotonic bending behaviour of TSOBs bolted beam to hollow square section column connection with inner stiffener

In the reported research results on T-head Square-neck One-side Bolts (TSOBs) bolted Endplate Connection (TSOB-EC), the failure of TSOB pulling-out due to the punching shear failure of Hollow Square Section Column (HSSC) wall is typical, which should be avoided. Two types of inner stiffeners that have H-section and double channel section are used to improve the punching shear resistance of the HSSC wall. At the same time, the inner stiffeners are used as connection splices to connect the upper column and the lower. The effect of the length and plate thickness for the stiffener on the connection performance are also studied. A total of six TSOBECs with stiffeners were tested under monotonic bending moment. The test results show that the stiffeners can avoid the bolt pulling-out failure and improve the deformation capacity of TSOBEC. The yield bending moment and peak bending moment of TSOBEC can be increased by 8.1%∼31.8% and 11.6%∼21.7% by double channel stiffeners, respectively, and improved by 69.3%∼72.6% and 22.5%∼39.4% by H-steel stiffeners, respectively. The analytical models for predicting the bending moment capacity of TSOBEC with stiffeners are proposed and the prediction results are accurate with an error within 5%. In addition, extended H-steel stiffener is recommended for designing the strengthened TSOBEC, and the cross-section of the stiffener needs to be calculated by the proposed models to ensure that the H-steel stiffener and HSSC do not deform even if the joint fails.

Comparison of Upper Neck Loading in Young Adult and Elderly Volunteers During Low Speed Frontal Impacts.

Cervical pain and injuries are a major health problem globally. Existing neck injury criteria are based on experimental studies that included sled tests performed with volunteers, post-mortem human surrogates and animals. However, none of these studies have addressed the differences between young adults and elderly volunteers to date. Thus, this work analyzed the estimated axial and shear forces, and the bending moment at the craniocervical junction of nine young volunteers (18–30 years old) and four elderly volunteers (>65 years old) in a low-speed frontal deceleration. Since the calculation of these loads required the use of the mass and moment of inertia of the volunteers' heads, this study proposed new methods to estimate the inertial properties of the head of the volunteers based on external measurements that reduced the error of previously published methods. The estimated mean peak axial force (Fz) was −164.38 ± 35.04 N in the young group and −170.62 ± 49.82 N in the elderly group. The average maximum shear force (Fx) was −224.42 ± 54.39 N and −232.41 ± 19.23 N in the young and elderly group, respectively. Last, the estimated peak bending moment (My) was 13.63 ± 1.09 Nm in the young group and 14.81 ± 1.36 Nm in the elderly group. The neck loads experienced by the elderly group were within the highest values in the present study. Nevertheless, for the group of volunteers included in this study, no substantial differences with age were observed.

Effect of soil-pile-structure interaction on seismic behaviour of nuclear power station via shaking table tests

To better understand the characteristics of the seismic response of nuclear power stations with fixed-base and pile-raft foundations, a series of shaking table tests were performed. The shaking table tests included three cases: free-field soil, fixed-base structure without soil, and superstructure with a pile-raft foundation embedded in the soil. One white noise excitation and three earthquake motions with different earthquake intensity were selected as the ground motion to identify the seismic response of the structure, raft, piles, and soils. The effects of earthquake intensity, earthquake frequency, soil-pile-structure interaction, and soil nonlinearity on the system dynamic responses were analysed. The test results show that the natural frequency and the damping ratio of the superstructure for the pile-raft foundation and the fixed-base structure are different, owing to the soil-pile-structure interaction effect. The acceleration amplification ratio of the fixed-base superstructure shows a significantly higher value than that of the superstructure with a pile-raft foundation. The average peak acceleration ratio of the raft for the pile-raft foundation (raft/soil surface) is 1.2. Under the long period wave excitations, the bending moment of the pile is greater than that of short-period wave excitations, and the peak bending moment occurs at the pile head. The vertical and horizontal displacement and residual displacement increases with the earthquake intensity. These observations suggested that the design of nuclear power station with a pile-raft foundation embedded in clay cannot be simplified as a fixed-base structure. Moreover, adopting pile-raft foundation for nuclear power station will extend the choice of finding suitable construction sites for the nuclear power stations, and the test results could provide references for engineers.