Cyclic Compressive Loading Research Articles

Compression and Fatigue Testing of High-Strength Thin Metal Sheets by Using an Anti-Buckling Device

BackgroundThe modelling of the sheet metal forming operations requires accurate and precise data of the material plastic behaviour along non-proportional strain paths. However, the buckling phenomenon severely limits the compressive strain range that could be used to deform thin metal sheets.ObjectiveThe main aim of this paper was to propose an effective device, that enables to determine of accurate stress-strain characteristics of thin metal sheet specimens subjected to axial deformation without buckling and with a special emphasis on friction correction.MethodsIn this paper, an anti-buckling fixture was proposed to assess the deformation characteristics of X10CrMoVNb9-1 (P91) power engineering steel, and DP500 and DP980 dual-phase steels, under compression loading. The fixture enables monitoring of the friction between the specimen and supporting blocks during the test, and thus the precise stress response of the material could be determined.ResultsThe effectiveness of the fixture was evaluated under tension–compression cyclic loading and during the compression tests in which high-strength thin metal sheets were successfully deformed up to 10% without specimen buckling. Furthermore, the successful determination of a friction force variation between supporting blocks and the specimen during tests enabled to determine an actual force acting on the specimen.ConclusionsThe proposed testing fixture was successfully assessed during the compression and cyclic tension–compression of high-strength thin metal sheets as no buckling was observed. Its advantage lies in adapting to change its length with specimen elongation or shrinkage during a test. The friction force generated from a movement of both parts of the device could be effectively monitored by the special strain gauge system during testing and thus its impact on the stress-strain characteristics could be successfully eliminated.

Effect of frequency on rock’s mechanical responses under multi-level compressive cyclic loading: an experimental investigation

Effect of frequency on rock’s mechanical responses under multi-level compressive cyclic loading: an experimental investigation

A combined experimental–numerical modelling approach for self-crack monitoring in conductive cementitious materials

This study proposes an innovative methodology by combining experimental testing and numerical modelling for self-evaluating the crack development of conductive cementitious materials based on piezoresistivity. Cube specimens enhanced with carbon black nanoparticles were subjected to cyclic and uniaxial compression loads individually for evaluating their piezoresistivity behaviour and analysing the crack sensing mechanism. A discrete element model (DEM) was utilised to extract crack development information which was correlated with resistivity variation in experiments for damage quantification. Acoustic emission was also utilised for the validation of resistivity-based crack monitoring. It was found that electrical resistivity started to rise at a relatively early stage of compression process, followed by an increasing rise before the specimen reached its peak strength and then a rapid surge when the specimen started to lose its load-bearing capacity. The results prove that the proposed approach can monitor crack development of conductive cementitious materials from a micro scale through resistivity variation and more precisely describe the damage accumulation. The study also demonstrates that DEM is capable of capturing failure mechanism of cementitious materials.

Analysis Method for Post-Impact Damage Development in Carbon Fiber Reinforced Laminate under Repeated Loading

In the current work, an analysis method for obtaining post-impact damage propagation under cyclic compressive load in flat carbon fiber reinforced plastic (CFRP) panels is presented. The solution for damage growth life is given based on the introduced hypothesis of reference damage mode (RDM). The critical size of damage for obtaining damage growth life was informed by the analysis of crack driving force versus damage size conducted using finite element analysis (FEA). The applicability of the damage tolerance principle for the case of compression–compression cyclic loading of the structural element containing impact damage is discussed and illustrated by the example. The results of using the introduced simplified approach to the calculation of characteristics of damage growth life suggest that the use of the slow-growth approach in composite structures is possible, though the necessity of obtaining the exact parameters of the damage growth rate equation with regard to the chosen crack driving force measure must be addressed.

Shape-Stabilized Monolithic Composite for Switchable Stiffness Based on Cellulose and Poly(stearyl methacrylate)

Stiffness-changing materials (SCMs) have recently attracted attention because their mechanical strength can be changed in response to external stimuli. Although the stiffness of SCMs can be adjusted considerably, these materials do not necessarily possess sufficient mechanical robustness in their soft state, thereby limiting their practical applicability. In this study, a stimuli-responsive polymer was incorporated into a porous supporting material to fabricate SCMs with high structural stability. Poly(stearyl methacrylate) (PSMA) was utilized as the responsive domain owing to the phase-changing behavior of its long alkyl side chain. A cellulose monolith (CM) was selected as the support owing to its outstanding chemical and physical stability despite its high porosity. The PSMA-modified CM (PSMA-CM) exhibited clearly detectable stiffness changes in response to temperature as a result of melting and crystallization of the PSMA domain. The Young’s modulus of PSMA-CM at 60 °C was half as large as that at 20 °C. Furthermore, during cyclic compressive loading–unloading tests, PSMA-CM displayed good shape recoverability, and the changes in its thermoresponsive stiffness were highly repeatable owing to both the stability of CM and the reversible responsive properties of PSMA. In addition, as opposed to CM, the stiffness of PSMA-CM decreased as the polarity of the surrounding solvent decreased. This result indicates that PSMA was composited not only onto the surface but also into the interior of the CM skeletal backbone. PSMA clearly reflects the variable stiffness of the monolith derived from the PSMA domain without impeding the dimensional stability of the material.

STRESS DISTRIBUTION OF MONOLITHIC AND VENEERED THREE-UNIT ZIRCONIA FDPS: A FINITE ELEMENT ANALYSIS.

To evaluate the effect of restoration design on fracture resistance and stress distribu0on of veneered and monolithic three-unit zirconia fixed partial dentures (FDPs) using finite element analysis (FEA). Identical epoxy resin replicas of mandibular second premolars and second molars (to serve as abutments for the three-unit bridges) were divided into four groups (n = 10): monolithic zirconia (MZ) restorations; conventional layering veneering technique (ZL); heat pressed-on technique (ZP); or CAD/CAM lithium-disilicate glass-ceramics (CAD-on). Specimens were subjected to compressive cyclic loading on the mesio-buccal cusp of the pontic (load range 50 to 600 N; aqueous environment; 500,000 cycles) in a universal testing machine. Data were statistically analyzed at 5% significance level with Fisher exact test and Kaplan-Meier survival analysis. 3D models were constructed in accordance with experimental groups. The stress distribution in each model was analyzed and evaluated according to the location and magnitude of the maximum principal stresses (MPSs) using ANSYS so\ware. Specimens from ZL and ZP groups failed at different stages of the 500,000 cycles fatigue, while CAD-on and MZ restorations survived the fatigue test. Statistically, there was a significant difference between the groups (P < .001). The MPS were located under the mesial connector in both monolithic and bilayered three-unit zirconia FDPs. These stresses were found to be higher in monolithic geometries compared to bilayered zirconia FDPs. Monolithic threeunit zirconia and CAD-on zirconia frameworks resulted in superior fracture resistance. Restora0on design significantly affected the stress distribu0on of three-unit zirconia FDPs.

Nonlinear behaviour of corrosion damaged low-strength short reinforced concrete columns under compressive axial cyclic loading

New codes have recently introduced seismic detailing for new structures. However, there are still older reinforced concrete (RC) structures without proper ductile detailing for earthquake resistance in seismic-prone areas. These structures are further impacted by the corrosion of their embedded reinforcing bars, which further reduces the strength and ductility under axial cyclic loading. This paper summarises the results of an experimental investigation performed on low-strength short RC columns, with different confinement configurations, subject to varying degrees of corrosion to investigate their structural responses to axial cyclic loading. The experiment was conducted on 30 short RC columns (square and circular) with three levels of confinement and steel reinforcement corrosion loss ranging from 0% to ∼ 30% subjected to cyclic compressive loading. The test results show that corrosion and inadequate confinements have a significant negative impact on the structural responses of corroded columns.

Seismic Behaviour of CFST Space Intersecting Nodes in an Oblique Mesh

The design of intersecting nodes in high-rise oblique mesh structures is a critical issue. The existing research on the intersecting nodes of oblique meshes mainly focuses on plane intersecting nodes and monotonic axial compression loads. The plane intersecting nodes cannot consider the contribution of the node’s out-of-plane angle and floor beam to the node’s out-of-plane stiffness in actual structures. In this paper, numerical analysis using ABAQUS was conducted to investigate the mechanical performance of space intersecting nodes of oblique meshes (OMSIN) under cyclic axial tension and compression loads, to provide a reference for the engineering application of oblique mesh structures in seismic regions. Six parameters were considered: the space intersecting angle, the plane angle symmetry coefficient, the plane intersecting angle, the out-of-plane constraint restraint, the steel content of the cross-section, and the concrete strength. The study showed that changes in the thickness of the steel tube wall are unfavourable for the uniform transmission of stress. Increasing the space intersecting angle significantly weakened the seismic performance, and the space angle affects the failure mode of the node. Asymmetric arrangements of the upper and lower plane angles caused nonlinear development of out-of-plane. The ultimate load and overall compressive stiffness of the specimen were positively correlated with the plane angle, and vertical constraints should be applied to the node position of components with plane angles greater than or equal to 70°. The out-of-plane constraint was a key factor affecting the seismic performance of the node, and it was proportional to the ultimate load of the component. In structural design, if the aim is to improve the mechanical performance of the component by increasing the steel content, more enormous out-of-plane constraints should be set to control plane external displacement strictly. The concrete strength is proportional to the ultimate axial load and axial stiffness, and its influence on the mechanical performance in the axial tension direction is not significant. Finally, a dimensionless skeleton curve model of the node was established. The existing formula for the bearing capacity of CFST columns was fitted to obtain the calculation formula for the axial yield and ultimate load of the OMSIN under cyclic loads.

Migration and remodeling in cartilage replacement materials – an in‐vitro bioreactor study

AbstractThis article presents a bioreactor study that investigates the influence of mechanical stimulation on cell migration in a cartilage replacement material. The bioreactor has been designed to carry out dynamic stimulation of cell‐seeded scaffolds, and it consists of a loading mechanism, a force‐measuring device, and a biocompatible chamber. The stimulation of the samples was carried out inside a bioreactor chamber, which simulates physiological conditions that are found in vivo. Cell migration was determined using two collagen scaffolds, a part that mimics native tissue and a second cell‐free implant. The two parts were positioned in direct contact with each other, and the samples were then subjected to cyclic compression loading for a two‐week time frame. We determined the cell viability, the number of migrated cells, and the migration depth into the initially cell‐free part of the specimen. The results from the dynamic loading were compared with an unloaded control sample. The cell migration effect was determined for different collagen concentrations, which allowed us to observe the relationship between the collagen content and cellular activity. The present results were compared to results from the literature.

3D Printing of Extracellular Matrix-Based Multicomponent, All-Natural, Highly Elastic, and Functional Materials toward Vascular Tissue Engineering.

3D printing offers an exciting opportunity to fabricate biological constructs with specific geometries, clinically relevant sizes, and functions for biomedical applications. However, successful application of 3D printing is limited by the narrow range of printable and bio-instructive materials. Multicomponent hydrogel bioinks present unique opportunities to create bio-instructive materials able to display high structural fidelity and fulfill the mechanical and functional requirements for in situ tissue engineering. Herein, 3D printable and perfusable multicomponent hydrogel constructs with high elasticity, self-recovery properties, excellent hydrodynamic performance, and improved bioactivity are reported. The materials' design strategy integrates fast gelation kinetics of sodium alginate (Alg), in situ crosslinking of tyramine-modified hyaluronic acid (HAT), and temperature-dependent self-assembly and biological functions of decellularized aorta (dAECM). Using extrusion-based printing approach, the capability to print the multicomponent hydrogel bioinks with high precision into a well-defined vascular constructs able to withstand flow and repetitive cyclic compressive loading, is demonstrated. Both in vitro and pre-clinical models are used to show the pro-angiogenic and anti-inflammatory properties of the multicomponent vascular constructs. This study presents a strategy to create new bioink whose functional properties are greater than the sum of their components and with potential applications in vascular tissue engineering and regenerative medicine.

Evaluation of Mechanically-Assisted Crevice Corrosion of Different Modular Dual Mobility Constructs

BackgroundModular dual mobility (MDM) acetabular component use is rising in total hip arthroplasty. However, concern of mechanically assisted crevice corrosion (MACC) at the shell-liner interface remains. We investigated shell-liner corrosion using retrieval analyses and corrosion chamber testing. MethodsWe analyzed fretting and corrosion on 10 matched pairs of 2 commercial MDM constructs (MDM1 and MDM2). Also, pristine pairs of Ti6Al4V shells and CoCrMo liners from 3 commercial dual mobility systems (MDM1, MDM2, and MDM3) were tested in vitro to model MACC performance. Three pairs of each were placed into an electrochemical chamber with stepwise increasing cyclic compression loads while measuring currents generated at the shell-liner taper. Onset fretting loads and fretting currents were calculated. ResultsCorrosion damage scores on retrieved components were low but higher in the MDM2 to MDM1 liners (P = .006), specifically outside the taper region (P = .00003). Fretting currents were higher in the MDM2 than in MDM1 or MDM3 (P = .011). Onset loads were also higher in the MDM2 (P = .001). ConclusionAmong retrieved liners, MDM2 tapers seem prone to non-mechanical corrosion modes. Higher onset loads and fretting currents in MDM2 tapers indicate greater MACC resistance but higher severity once corrosion begins. Differences among the devices were likely due to taper design and surface finish. Currents in all 3 were <5 μA, much lower than those observed with head-neck tapers. Our findings suggest that, among the types of corrosion observed in these MDM designs, mechanically driven corrosion may not be the most significant.

EX VIVO ORGAN MODEL AND SAMPLE HOLDER FOR INTERVERTEBRAL DISC STUDIES IN A NEW GENERATION OF MULTIAXIAL BIOREACTORS

A novel ex vivo intervertebral disc (IVD) organ model and corresponding sample holder were developed according to the requirements for six degrees of freedom loading and sterile culture in a new generation of multiaxial bioreactors. We tested if the model can be maintained in long-term IVD organ culture and validated the mechanical resistance of the IVD holder in compression, tension, torsion, and bending.An ex vivo bovine caudal IVD organ model was adapted by retaining 5-6 mm of vertebral bone to machine a central cross and a hole for nutrient access through the cartilaginous endplate. A counter cross was made on a customized, circular IVD holder. The new model was compared to a standard model with a minimum of bone for the cell viability and height changes after 3 weeks of cyclic compressive uniaxial loading (0.02-0.2 MPa, 0.2 Hz, 2h/ day; n= 3 for day 0, n= 2 for week 1, 2, and 3 endpoints). Mechanical tests were conducted on the assembly of IVD and holder enhanced with different combinations of side screws, top screws, and bone adhesive (n=3 for each test).The new model retained a high level of cell viability after three weeks of in vitro culture (outer annulus fibrosus 82%, inner annulus fibrosus 69%, nucleus pulposus 75%) and maintained the typical values of IVD height reduction after loading (≤ 10%). The holder-IVD interface reached the following highest average values in the tested configurations: 320.37 N in compression, 431.86 N in tension, 1.64 Nm in torsion, and 0.79 Nm in bending.The new IVD organ model can be maintained in long-term culture and when combined with the corresponding holder resists sufficient loads to study IVD degeneration and therapies in a new generation of multiaxial bioreactors.

Mechanical characterization of a novel biomimetic artificial disc for the cervical spine

A novel biomimetic artificial intervertebral disc (bioAID) replacement implant has been developed containing a swelling hydrogel representing the nucleus pulposus, a tensile strong fiber jacket as annulus fibrosus and titanium endplates with pins to primarily secure the device between the vertebral bodies. In this study, the design safety of this novel implant was evaluated based on several biomechanical parameters, namely compressive strength, shear-compressive strength, risk of subsidence and device expulsion as well as identifying the diurnal creep-recovery characteristics of the device.The bioAID remained intact up to 1 kN under static axial compression and only 0.4 mm of translation was observed under a compressive shear load of 20 N. No subsidence was observed after 0.5 million cycles of sinusoidal compressive loading between 50 and 225 N. After applying 400 N in antero-posterior direction under 100 N axial compressive preload, approximately 2 mm displacement was found, being within the range of displacements reported for other commercially available cervical disc replacement devices. The diurnal creep recovery behavior of the bioAID closely resembled what has been reported for natural intervertebral discs in literature.Overall, these results indicate that the current design can withstand (shear-compression loads and is able to remain fixed in a mechanical design resembling the vertebral bodies. Moreover, it is one of the first implants that can closely mimic the poroelastic and viscoelastic behavior of natural disc under a diurnal loading pattern.

Multifunctional Concrete with Graphene-Based Nanomaterials and Superabsorbent Polymer

This study reports on the development of a multifunctional concrete using graphene nanoplatelet (GnP) and sodium polyacrylate (SP) superabsorbent polymer. A combination of concrete functionalities was convened to improve, i.e., high strength and durability along with smart properties such as self-healing and self-sensing. GnP (0.05% by weight of cement) and SP (0.11% by weight of cement) were dispersed in concrete. Compared to the control concrete mix (no GnP and SP), the compressive strength increased 14% by GnP and decreased 9% by SP, and their combination resulted in a 6% enhancement in strength. The durability performance of concrete samples under coupled degradation mechanisms of freeze-thaw and chloride ion ingress suggested that SP in concrete has a better performance than GnP in concrete. SP in concrete shows self-sealing abilities resulting in less chloride ion penetration. However, the combined effect of both GnP and SP in concrete resulted in the maximum reduction in chloride ion penetration depth under freeze-thaw, a 42% reduction compared to the control mix. Microstructural analysis was conducted and found to resist the effects of freeze-thaw and reduce chloride ion penetration in modified concrete compared to the control concrete mix. GnP developed self-sensing abilities in concrete, resulting in about 12.7% fractional change of electrical resistance under 10 KN of cyclic compressive loading. The synergic impact of GnP and SP possesses a new prospect for developing highly efficient multifunctional concrete.

Experimentally dissociating the overuse mechanisms of endplate fracture lesions and Schmorl's node injuries using the porcine cervical spine model

BackgroundCompared to the documented overuse mechanisms of endplate fracture lesions, the cause of Schmorl's node injuries remains unknown, despite existing hypotheses. Therefore, this study aimed to examine and dissociate the overuse injury mechanisms of these spinal pathologies. MethodsForty-eight porcine cervical spinal units were included. Spinal units were randomly assigned to groups that differed by initial condition (control, sham, chemical fragility, structural void) and loading posture (flexed, neutral). Chemical fragility and structural void groups involved a verified 49% reduction in localized infra-endplate trabecular bone strength and removal of central trabecular bone, respectively. All experimental groups were exposed to cyclic compression loading that was normalized to 30% of the predicted tolerance until failure occurred. The cycles to failure were examined using a general linear model and the distribution of injury types were examined using chi-squared statistics. FindingsThe incidence of fracture lesions and Schmorl's nodes was 31(65%) and 17(35%), respectively. Schmorl's nodes were exclusive to chemical fragility and structural void groups and 88% occurred in the caudal joint endplate (p = 0.004). In contrast, 100% of control and sham spinal units sustained fracture lesions, with 100% occurring in the cranial joint endplate (p < 0.001). Spinal units tolerated 665 fewer cycles when cyclically loaded in flexed postures compared to neutral (p = 0.015). Furthermore, the chemical fragility and structural void groups tolerated 5318 fewer cycles compared to the control and sham groups (p < 0.001). InterpretationThese findings demonstrate that Schmorl's node and fracture lesion injuries can result from pre-existing differences in the structural integrity of trabecular bone supporting the central endplate.

Effects of cyclic loading and unloading rates on the energy evolution of rocks with different lithology

The deformation-to-failure process of rocks is accompanied by energy dissipation and release, indicating that it is an energy conversion process. To investigate the influence of lithology as well as the loading and unloading rates on the evolution and distribution of rock energy, the MTS 816 rock mechanics testing system was used for performing uniaxial compression and uniaxial cyclic loading–unloading tests on the 165 samples of four rock types. The total energy density, elastic energy density, and dissipated energy density absorbed by rocks of different lithology were obtained, and the evolution and distribution laws of lithology and loading and unloading rates on the accumulation and dissipation of rock energy were investigated. The results revealed that the energy density of all rock samples increased nonlinearly with the increase in axial stress, and the elastic energy density increased gradually first and subsequently rapidly with the increase in the axial stress. The evolution curves were not affected by the loading and unloading rates. The dissipated energy density increased gradually with the increase in axial stress, and the discrepancy of the evolution curve was large. The proportion of the elastic energy density varied nonlinearly with the increase in axial stress or the cycle index, exhibiting the evolutionary process of increasing, then stabilizing, and finally decreasing. However, the proportion of the dissipated energy density exhibited an opposite trend. The elastic energy accumulated in the rock sample at the pre-peak stage was considerably higher than the dissipated energy, and the proportion of the elastic energy density was large. With the increase in loading and unloading rates, the proportion of elastic energy exhibited an approximate growth trend, and the proportion of dissipated energy exhibited an approximate decreasing trend.

Anti-inflammatory therapy enables robot-actuated regeneration of aged muscle.

Robot-actuated mechanical loading (ML)-based therapies ("mechanotherapies") can promote regeneration after severe skeletal muscle injury, but the effectiveness of such approaches during aging is unknown and may be influenced by age-associated decline in the healing capacity of skeletal muscle. To address this knowledge gap, this work used a noninvasive, load-controlled robotic device to impose highly defined tissue stresses to evaluate the age dependence of ML on muscle repair after injury. The response of injured muscle to robot-actuated cyclic compressive loading was found to be age sensitive, revealing not only a lack of reparative benefit of ML on injured aged muscles but also exacerbation of tissue inflammation. ML alone also disrupted the normal regenerative processes of aged muscle stem cells. However, these negative effects could be reversed by introducing anti-inflammatory therapy alongside ML application, leading to enhanced skeletal muscle regeneration even in aged mice.

Fracture features of brittle coal under uniaxial and cyclic compression loads

Under the effects of complex geological and stress environments, burst hazards continue to be a major challenge for underground space utilization and deep resources exploration as its occurrence can lead to personnel causalities, equipment damage and structural collapse. Considering the stress path experienced by in-situ coal body, cyclic loading appears in quite various forms for instance shearer cutting, overlying strata breakage, hydro-fracturing and blasting, during tunnel, mining and underground space utilizing process. The stability of the underground coal body subject to periodic loading/unloading stress is extremely important for maintain the function of designed engineering structure for waste storage, safe mining, roadway development, gas recovery, carbon sequestration and so on. The mechanical properties of hard rock subject to cyclic fatigue loads has been intensively investigated by many researchers as the rock burst induced by supercritical loads has long been a safety risk and engineering problems for civil and tunneling engineering under deep overburden. More recently, the mechanical properties of coal samples under cyclic fatigue loads is investigated from the aspect of hysteresis, energy dissipation and irreversible damage as the burst hazards of brittle coal is rising in many countries. However, the crack propagation and fracture pattern of brittle coal need more research to understand the micro mechanism of burst incubation subject to cyclic fatigue loads as brittle coal can store more elastic strain energy and rapidly release the energy when its ultimate strength once reached. This research studied the internal crack status corresponding to different cyclic fatigue loading stage of brittle coal samples. The AE monitoring was applied during the uniaxial and cyclic loading process of brittle coal samples to record the crack intensity of samples at different loading stages. The damage evolution curve corresponding to loading status was then determined. The fracture pattern of coal samples determined by micro-CT scan was observed and discussed. It has been found by this paper that brittle coal of uniaxial compression tests demonstrated sudden failure caused by major splitting fracture while that of cyclic fatigue tests experienced progressive failure with mixture fracture network.

Rutting Predictions in Flexible Airfield Pavements Using a Newly Modified Drucker–Prager Combined Hardening Model with Progressively Evolving Yield Surface

Granular materials subjected to compressive cyclic loading of constant amplitude when modeled using an isotropic hardening, elastoplastic Drucker-Prager (DP) model do not accumulate significant plastic strain beyond the first loading cycle. This can lead to predictions of permanent deformations in airfield asphalt pavements that do not compare well with experimental observations. Accordingly, this paper proposes a modification to the existing DP model as a means of accounting for this shortcoming. A new parameter, γ, is introduced, which causes the yield surface to progressively evolve and shrink in size during successive load cycles to account for microphysical restructuring of the granular material during constant amplitude cyclic loading. The constitutive model is implemented within the finite element code ABAQUS through the user material subroutine UMAT. The model is subsequently tested via 2D finite element analysis on pavement sections by applying it to the granular base and modeling all other layers as linear elastic. Validation is undertaken by comparing rutting with field experimental values from an accelerated pavement testing program. Increased equivalent plastic strain and vertical plastic strains are observed with this modification, thereby resulting in rutting values that are significantly closer to the experimental data than those obtained with the classical DP model.

Compression-bending behavior of irregular pentagonal CFT columns with different cavity structures: Experimental study

This paper reported the test results of six irregular pentagonal concrete filled steel tube (CFT) columns with different cavity structures. The columns were tested under a constant axial compression and lateral low cyclic load. The test parameters are the lateral loading direction, cross-sectional cavity quantities, and with or without embedded reinforcements. The influence of these parameters on failure mode, strength, elastic-plastic deformability, energy dissipation ability was investigated. It was found that, irregular pentagonal CFT columns exhibit favorable ductility and energy dissipation ability. The multi-cavity structure significantly increases strength, while the reinforcements effectively improve ductility. Also, the bottom cross section strain distribution nephogram was mathematic fitted according to the measured gauge values. And it was founded that the bottom cross-sectional deformation obeys the plane cross section assumption before and at peak load point. And then, a calculation model using fiber model method was established considering difference among the cavity structures. The lateral load versus displacement curves, and axial load versus ultimate moment correlation curves are all predicted. Analysis shows that the constitutive relationship of confined concrete suggested by the author is better than available Han's in the prediction accuracy.