Compressive Capacity Research Articles

Compressive behaviour and capacities of S690 high strength steel welded π-shaped and cruciform section stub columns

This paper reports experimental and numerical investigations into the cross-sectional behaviour and resistances of S690 high strength steel welded π-shaped and cruciform section stub columns under compression. An experimental investigation was firstly carried out on five S690 high strength steel welded π-shaped sections and five S690 high strength steel welded cruciform sections (covering both non-slender and slender sections) and included material tensile coupon tests, initial local geometric imperfection measurements and twenty stub column tests. The experimental investigation was supplemented by a numerical modelling investigation, where finite element models were firstly developed to simulate test structural responses and subsequently adopted to conduct parametric studies to generate further numerical data. On the basis of the obtained experimental and numerical data, the relevant design rules for high strength steel welded sections under compression, as set out in the European code, American specification and Australian standard, were assessed. The assessment results indicated that (i) the European code and American specification led to overall accurate and consistent cross-section compression resistance predictions for S690 high strength steel welded π-shaped sections, but provided slightly conservative and scattered resistance predictions for their cruciform section counterparts, and (ii) the Australian standard was accurate and consistent when used for non-slender S690 high strength steel welded π-shaped sections, but the design resistances were conservative and scattered for slender S690 high strength steel welded π-shaped sections as well as non-slender and slender S690 high strength steel welded cruciform sections.

Experimental behavior of axially loaded circular high-strength concrete-filled high-strength steel tubular stub columns after exposure to fire

The high-strength concrete-filled high-strength steel tubular (HCFHST) column is an innovative type of high-performance steel-concrete composite component, which has a broad prospect for engineering applications. To investigate the axial compressive behavior of post-fire HCFHST stub columns with circular cross-sections, twenty-five specimens were heated following ISO 834 standard fire and then loaded to failure under axial compression after being cooled. The effects of various heating durations, concrete and steel strength on the temperature distribution, spalling of the steel-concrete interface, post-fire ultimate bearing capacity and axial stiffness were analyzed. The residual ultimate capacity and axial stiffness of HCFHST stub columns experience a pronounced decrease as the heating duration increases. High strength steel has no significant contribution to the enhancement of the post-fire axial stiffness of HCFHST stub columns, and the effect level of high-strength concrete on the failure load of composite columns subjected to different heating durations is similar. Finally, the applicability of relevant equations for the residual compressive capacity of the ordinary strength CFST column to HCFHST stub columns was evaluated. The evaluation results revealed that available methods of conventional strength CFST stub columns cannot obtain accurate post-fire resistance predictions of circular HCFHST stub columns.

An Investigation into the Variables Influencing the Structural Bamboo Architecture Using Filled Concrete and Cement Mortar

Bamboo, as a green building material, plays a vital role in construction. Bamboo has good properties and appearance, making it highly attractive for building structures and designs. Since the compressive capacity of bamboo is considerably lower than its tensile capacity, with the ratio typically ranging between 300% to 900%, this limits its application dimensions in construction. Therefore, filling the original bamboo structural members with specific materials or applying different connection methods can not only maintain the appearance of the bamboo structure but also improve its compressive capacity and overall durability, thus expanding the application range of bamboo structural members and enhancing the performance of the architectural design process. Two hollow bamboo specimens were among the eight BFC specimens tested for this paper. Key components such as transverse stiffeners, steel bars, filler materials, and bamboo nodes were examined for their influence on the specimens’ ductility, peak strain, ultimate bearing capacity, and failure mechanisms. The test results showed that the ratio of the ultimate bearing capacity of BFC specimens to hollow bamboo samples could reach up to 538%, while the peak strain differences were minimal. A non-linear finite element model was developed and its accuracy confirmed based on the test results. This work proposes a new approach to determine the final axial compressive capacity of BFC columns by creating an elastic model of transversely isotropic cylinders. As a result, the primary goal of this study is to establish a foundation for more scientific building design techniques and procedures by examining the axial compression mechanics of structural bamboo filled with cement and concrete (BFC) and how it influences building design.

Numerical and Theoretical Studies on Axial Compression Performance of Modular Steel Tubular Columns Grouped with Shear-Key Connectors

Shear-keyed inter-modular connections (IMCs) are integral components of high-rise modular steel structures (MSSs), providing robust interconnectivity to support grouped tubular columns across modules, thereby introducing column discontinuities and distinctive structural behavior. This study conducted a comprehensive numerical assessment and theoretical analysis of the axial compression behavior of grouped tubular columns based on a validated finite element model (FEM), which captured the member-to-structural level behavior of steel hollow section (SHS) columns and accommodated geometric imperfections. An FEM was initially developed and validated using 28 axial compression tests documented in the literature, comprising 15 tests on cold-formed and 13 on hot-rolled steel hollow section (SHS) columns. The primary parameters explored in tests included material properties (stainless/carbon), processing methods (cold-formed/hot-rolled), cross-section sizes (D/B), cross-sectional or member slenderness ratios (D/tc, B/tc, or Lc/r), and the number of columns (1, 7, and 11). A comprehensive parametric numerical study involving 103 grouped tubular column FEMs then investigated the influence of initial imperfection, shear-key height (Lt), thickness (tt), steel tube length (D), width (B), thickness (tc), and height (Lc) alongside the effects of space between tube and key, and the gap between tubes. The results indicated that the load-shortening behavior of the grouped columns consists of linear elastic, inelastic, and recession stages. The failure modes observed primarily displayed an S-shaped pair of inward and outward local buckling on the outer sides and double S-shaped local buckling on the interior sides. The buckling arose near the shear key or at 1/4 or 1/2 of the column height. None of the considered models experienced global buckling. Increasing tt, Lt, tc, D, or B enhances strength and stiffness, while Lc or Lc/r linearly affects stiffness and ductility. The columns’ nominal axial strength was reduced because of the shear keys, which decreased compression yielding and caused localized elastic buckling. Subsequently, the theoretical analysis revealed that the design codes do not capture this behavior, and thus, their capacity estimate yields inaccurate findings. This discrepancy renders existing code prediction equations, including those from Indian (IS800), New Zealand (NZS400), European (EC3:1-1), Canadian (CSA S16), American (AISC360-16), and Chinese (GB50017) standards, as well as the model proposed by Li et al., non-conservative. To assure conservative results, the paper recommended modification of existing standards and proposed prediction equations based on a fourth-order differential equation that describes the actual behavior of modular steel columns grouped with shear keys. The proposed design approach accurately predicted the axial compression capacity of modular steel-grouped columns, proving conservative yet effective. This provides valuable data that could transform design and construction techniques for MSSs, extending to various column and IMC forms through adaptable design parameters. This enhancement in structural performance and safety significantly contributes to the advancement of modular construction practices.

Research on axial compressive behavior with circular steel tubes reinforced by sleeved tube

To study the behavior of the axial compression circular steel tube reinforced by a sleeved tube, the finite element model of casing tube reinforcement was established based on the existing research results. The mechanical properties and failure mechanism of the reinforced casing tube specimen were systematically studied by finite element parameter analysis. The results show that in the elastic stage, the outer-sleeved tube is less involved in the force. After entering the elastic-plastic stage, the outer-sleeved tube starts to work and is stressed together with the inner steel tube. Slenderness ratio, diameter-thickness ratio, and ferrule spacing are the main factors affecting the ultimate axial compression capacity of casing reinforcement components. When other variables are consistent, the ultimate axial compression capacity of specimens after reinforcement with different initial stress ratios is basically the same. The increase of the ferrule width and thickness has little effect on the improvement of the ultimate axial compression capacity of the reinforcement components. The load value after casing reinforcement calculated by the current standard is much higher than the test load value of the component. According to the results of parameter analysis and the current standard, the design method for the ultimate axial compression capacity of the circular steel tube reinforced by a sleeved tube was put forward.

Energy characteristics and damage constitutive model of pre‐cracked granite with or without filling materials

AbstractIn order to study the effects of pre‐crack inclination angle and filling material on granite, uniaxial compression tests were performed on pre‐cracked granite specimens without filling material and specimens filled with epoxy resin, gypsum, and organosilicon. Results indicate that the peak strength and apparent stiffness of pre‐cracked granite without filling materials increase with increasing pre‐crack inclination angle. The strain energy absorbed by the filling material improves the energy storage limit, inhibits the energy release effect when microcracks are connected to each other, and ultimately improves the compressive resistance and energy storage capacity. The strengthening effect of gypsum and epoxy resin is relatively better, which is more significant when the pre‐crack inclination angle equals 0°–60°. Finally, a damage constitutive model is established, which is in good agreement with the test and numerical simulation data. The results can provide reference for the research of grouting reinforcement of rock masses.

Preparation and Properties of Elastic Mullite Fibrous Porous Materials with Excellent High-Temperature Resistance and Thermal Stability.

Mullite fiber felt is a promising material that may fulfill the demands of advanced flexible external thermal insulation blankets. However, research on the fabrication and performance of mullite fiber felt with high-temperature resistance and thermal stability is still lacking. In this work, mullite fibers were selected as raw materials for the fabrication of mullite fibrous porous materials with a three-dimensional net structure. Said materials' high-temperature resistance and thermal stability were investigated by assessing the effects of various heat treatment temperatures (1100 °C, 1300 °C, and 1500 °C) on the phase composition, microstructure, and performance of their products. When the heat treatment temperature was below 1300 °C, both the phase compositions and microstructures of products exhibited stability. The compressive rebound rate of the product before and after 1100 °C reached 92.9% and 84.5%, respectively. The backside temperature of the as-prepared products was 361.6 °C when tested at 1500 °C for 4000 s. The as-prepared mullite fibrous porous materials demonstrated excellent high-temperature resistance, thermal stability, thermal insulation performance, and compressive rebound capacity, thereby indicating the great potential of the as-prepared mullite fibrous porous materials in the form of mullite fiber felt within advanced flexible external thermal insulation blankets.

Fracture Pre-propping and Temporary Plugging for Formation Damage Control in Deep Naturally Fractured Tight Reservoirs

Summary To address the challenges of formation damage related to drill-in fluid loss into deep reservoir fractures during the drill-in process, we propose pre-propping and temporary plugging (PPTP) technology as an integrated solution in this paper. The PPTP approach combines high-strength bridging (HSB) materials with self-degrading filling (SDF) materials for efficient fracture plugging during lost circulation and effective fracture propping during oil and gas production from deep naturally fractured reservoirs. HSB material with good mechanical properties and SDF material with a controllable degradation cycle are developed and systematically evaluated. Fracture plugging tests and stress sensitivity experiments are conducted to evaluate the transformation effect of fracture plugging zones on fracture propping zones. Research results show that the developed HSB material exhibits a high compressive capacity and friction coefficient, which maintains a crushing rate below 3% under 60 MPa pressure and an average friction coefficient of 1.56. The degradation ratio of SDF material increases with temperature and pH value. The degradation cycle can reach up to 168 hours under the conditions of 120°C and pH = 13, which ensures continuous stable fracture plugging and lost-circulation control during the drill-in process. The PPTP technology, combining HSB and SDF components, efficiently plugs fractures with widths ranging from 1.0 mm to 3.0 mm, with a maximum plugging pressure of up to 10.16 MPa. HSB material props the fractures after SDF degrades, preventing fracture closure and converting the fracture plugging zone into a propping zone. The stress sensitivity damage of reservoir fractures can be effectively mitigated, preserving and enhancing fracture conductivity. Thus, the PPTP technology shows great potential for the integration solution of drill-in fluid loss and formation damage in deep naturally fractured reservoirs.

Experimental study on compressive capacity of stainless steel S35657 columns with welded box section and I-section under axial compression

Compared with conventional stainless steel, a new type of stainless steel, S35657, has broad application prospects owing to its advantages of high strength and low production costs. In this study, the compressive capacity of stainless steel S35657 columns was investigated. A total of 13 specimens were designed and tested, including 4 box section specimens and 9 I-section specimens (4 buckling around the major axis and 5 buckling around the minor axis). Complementary chemical composition analyses, material tensile tests, residual stress measurements, and initial geometric imperfection measurements were also conducted. The mechanical properties of the material, as well as its residual stress distribution model, failure mode, load-displacement curve, and compressive capacity, were reported and analyzed. For box section columns, when the slenderness ratio increased from 29 to 55.2, the compressive capacity of the column decreased by 27.6 %. The accuracy and safety of design methods specified in European standard EN 1993–1–4, American specification ASCE-8–02, and Chinese specification CECS 410 were assessed based on the test results. The result shows that EN 1993–1–4 is overly conservative in its compressive capacity calculations, whereas ASCE-8–02 overestimates the compressive capacity with a higher level of scatter exhibited. The methods of CECS 410 for predicting the compressive capacity of welded stainless steel S35657 columns are more accurate compared with the methods of EN 1993–1–4 and ASCE-8–02.

On the reusable compressive behavior of multi-directional auxetic origami metamaterials

Origami metamaterials exhibit abnormal mechanical properties through artful structural design. To further explore the mechanical behavior of reentrant metamaterials, a multi-directional auxetic origami metamaterial (AOMM) was designed, and its negative Poisson’s ratio effect was analyzed through the diagram of load bearing and deformation. Theoretical models related to geometric parameters, relative density, folding rate, equivalent elasticity and load plateau were established to reveal the deformation transformation mechanism, and the influence of size parameters on the equivalent elastic constants was drawn. Using thermoplastic polyurethane (TPU) as the substrate, two types of multi-directional AOMMs were fabricated by 3D printing, and quasi-static compression experiments were performed. The results show that the TPU AOMMs has a reusable compressive capacity, whose compressive mechanical behaviors are mainly contributed by the buckling instability and large deformation of sidewall. There is a coupling effect between the cross connection boundaries, which results in the difference in mechanical properties of AOMM with different geometric sizes. The prediction results of relative density, load plateau and yield strain through equivalent theories approximate that of experimental results. Simultaneously, finite element analyses were conducted, which agrees well with the experiments. These foundings may provide reference for the design and application of novel auxetic or origami metamaterials.

Global stability capacity of partially encased composite columns with cruciform-shaped section under axial compression

This paper undertakes a test investigation and finite element (FE) analysis of the stability behavior of partially encased composite (PEC) columns with cruciform-shaped sections. Two PEC column specimens with the same geometric size were tested under axial compression loading, and the difference between the specimens is that the main steel components (MSCs) made of solid-web steel and castellated steel, respectively. The test results show that the two columns exhibited similar failure modes: concrete crushing and global flexural instability. Furthermore,the capacities of both columns were found to be smaller than the corresponding theoretical axial capacities of the composite column section. The test and FE results show that the bearing capacity of the PEC columns with solid-web MSCs is higher than that of the PEC columns with castellated MSCs. The size of the web openings exerts a considerable detrimental impact on the compressive capacity of the PEC column, while the shape and spacing of the openings have little influence on the capacity. In addition, design equations were proposed to predict the stability capacity of the cruciform-shaped section PEC column with both solid-web MSCs and castellated MSCs, in the equations, the castellated MSCs were simplified as the lattice columns with batten plates.

Compressive bearing capacity of steel dual-angle with cruciform welding filler plates based on failure modes

The bearing capacity of steel dual-angle with cruciform welding filler plates (i.e., DACWP) under axial compression is the primary purpose of this paper. Six DACWP specimens were prepared with different width-thickness ratios (i.e., 15.63, 12.50, 10.42) and slenderness ratios (i.e., 45, 75). Axial compression tests were carried out to analyze the failure mode, load-displacement curve, and load-strain history of the specimens. Subsequently, a finite element model was established and calibrated by test results, providing further insights into the influence of the slenderness ratio and width-thickness ratio on the bearing capacity of DACWP. Finally, a calculation method of bearing capacity based on different failure modes was proposed. The results show that, with a constant width-thickness ratio, the DACWP transits from torsion failure to bending failure with the increase of slenderness ratio. Particularly, the transition slenderness ratio of failure is found to be proportional to the slenderness ratio and the width-thickness ratio. In the case of torsion instability, the slenderness ratio has little effect on the bearing capacity, while the width-thickness ratio exhibits an opposite effect. Specifically, the bearing capacity of DACWP decreases with the increase of slenderness ratio and width-thickness ratio. The calculation formula proposed in this paper can be used to calculate the bearing capacity of DACWP.

The role of working memory capacity in the temporal compression of episodic memories: An individual differences approach.

Remembering past events usually takes less time than their actual duration-their unfolding is temporally compressed in episodic memory. The rate of temporal compression (i.e., the ratio of the actual duration of an event to the duration of its remembering) is not constant but varies between individuals and as a function of the structure of events (e.g., how they can be divided into shorter subevents). However, the cognitive mechanisms underlying these variations remain poorly understood. Given its role in the encoding and retrieval of information in episodic memory, working memory (WM) capacity could be an important determinant of temporal compression rates. We tested this hypothesis in two experiments in which we asked participants to watch and then mentally replay short videos showing people engaged in daily life activities. We showed that temporal compression rates depend on an interplay between WM and the structure of the remembered events: participants' WM capacity (assessed using complex span tasks) was negatively associated with temporal compression rates, but only when the remembered events contained few event boundaries (i.e., few subevents). This suggests that the temporal compression of events in episodic memory emerges when some of the subevents to be retained are too long to be fully represented in WM. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Mechanical behavior of eccentrically loaded UHPC-encased CFST medium-long columns

To study the eccentric compression performance and failure mechanism of ultra-high performance concrete (UHPC) encased concrete-filled steel tubular (CFST) medium-long columns (UC-CFST medium-long columns), a total of 27 UC-CFST column specimens were tested under eccentric compression with eccentricity and slenderness ratio as the main parameters. After verified by experimental results, the finite element (FE) analysis of UC-CFST medium-long columns with actual structural cross-sectional size under eccentric compression was further carried out. It is found that as the slenderness ratio and eccentricity increased, the bending stiffness and the ultimate bearing capacity of the UC-CFST columns decreased gradually, and the failure mode changed from strength failure to instability failure, and the smaller the proportion of encasing UHPC area, the greater the upper-bound slenderness ratio of strength failure. Moreover, the influence of eccentricity was nonlinearly coupled with slenderness ratio on the eccentric compressive bearing capacity of UC-CFST medium-long columns. Finally, a calculation method of ultimate load-bearing capacity of UC-CFST medium-long columns considering the influence of eccentricity and slenderness ratio was proposed, which had good calculation accuracy with experimental and numerical results.

Comparative study on the compression characteristics of coal and biomass powder bed

Biomass substitution for fossil energy is desirable to achieve carbon emission reductions, and the storage and transportation process of biomass is governed by its compressibility. The compression characteristics of pulverized coal, rice husk and lignocellulose were compared under mechanical and gas pressurization, respectively. The experimental results showed that the descending order of relative packing density (RPD) was lignocellulose > rice husk > pulverized coal under mechanical pressurization, while an opposite trend was observed under gas pressurization. The cohesion properties were rationally correlated with the packing behavior of powder bed, and the differences in RPD order were discussed as the higher cohesion corresponding to a larger void fraction. For mechanical pressurization, biomass had higher void fraction, which was directly linked to larger RPD. On the contrary, gas permeated easily into the biomass powder bed, and the lower pressure drop decreased the compression capacity of gas pressurization. In addition, a model for predicting the RPD was proposed with an error of ± 5 %.

Supplemental Material for The Role of Working Memory Capacity in the Temporal Compression of Episodic Memories: An Individual Differences Approach

Supplemental Material for The Role of Working Memory Capacity in the Temporal Compression of Episodic Memories: An Individual Differences Approach

Axial performance of concrete-filled GFRP tube columns jacketed by outer stainless steel tube and sandwiched concrete

The concrete-filled FRP tube (CFFT) column, a prevalent and crucial structural element in marine environments, requires reinforcement measures to enhance its operational performance. This paper introduces a novel strengthening technology involving sandwiched concrete and stainless steel tube jackets. By conducting axial compression tests on two CFFT columns and nine reinforced columns, the failure modes, load-axial deformation curves, and load-strain relationships were analysed in this study. Additionally, the influence of outer steel tube thickness (3.0 mm, 4.0 mm, 5.0 mm) and sandwiched concrete strength grades (C50, C60, C70) on the axial compressive performance of the reinforced columns was investigated. The findings indicated that the proposed reinforcement method effectively mitigated the brittle failure associated with the original CFFT column. The external stainless steel tube played a crucial role in restraining lateral deformation of the internal CFFT column, thereby enhancing the axial compressive bearing capacity. Through theoretical analysis on the components in reinforced columns, a calculation formula for the axial compressive capacity of the reinforced column was derived according to the unified theory and the double-shear unified strength theory.

Synchronous Fluorescence Spectrometry (SFS) with Multivariate Calibration for the Determination of Polycyclic Aromatic Hydrocarbons (PAHs) and Their Oxygen Analogs in Printer Toner

Synchronous molecular fluorescence with multivariate calibration was investigated to assay seven polycyclic aromatic hydrocarbons (PAHs) and three oxygenated derivatives (O-PAHs) in printer toner. Great sensitivity and a good data compression capacity were achieved; therefore, a relatively small number of factors were used. Correlation coefficients above 0.95 for the calibration functions were obtained, and recoveries lie between 70 and 130% in analyzing synthetic samples (13 PCs). For the real samples assayed, recoveries between 81 and 125% were obtained when compared to the results obtained by gas chromatography – tandem mass spectrometry (GC-MS/MS). Despite a certain loss in accuracy when compared to chromatography, the proposed methodology is faster, simpler, and lower in cost. The multivariate tool proved to be an expeditious alternative for screening toner in relation to the presence and abundance of PAHs and derivatives.

Mining waste as an alternative aggregate in brick production for carbon capture and storage

Abstract Production of waste rocks and overburden from ore mining in open-pit mines can cause undesirable environmental impacts. Thus, this study aims to tackle the issue of waste production from mining areas by utilizing mining waste to sequester CO2 and to evaluate its potential for carbon capture in cementitious material. This study attempts to evaluate the effect of mine waste ratio and carbonation curing time on physico-mechanical behavior of bricks. The bricks were fabricated using different ratios of mine waste, i.e. 20 – 40 % in the mix design. Carbonation curing between 1 – 3 hours was applied during the brick fabrication to estimate CO2 capture of the brick product. The brick performances were evaluated based on the compressive strength, water absorption and carbon capture capacity. It was found that curing time at 28 days provided the greatest compressive strength of the brick and greater performance was observed at 40 % replacement with the mine waste. Carbonation curing improved the brick performance with higher compressive strength and lower water absorption at longer exposure time of 3-hour carbonation. The resulting CO2 uptake was found to increase with the increase of carbonation time and at higher ratio of mine waste replacement. The CO2 capture capacity was between 0.45 – 0.58 % for bricks containing 20 – 40 % of mine waste, which corresponds to 9.4 – 16.3 g CO2/brick. Therefore, it has been shown that the use of mining waste as partial replacement for cementitious material was capable in improving the brick performance with incorporation of carbonation curing process.

Residual compressive strength of locally corroded circular CFST stub columns: An experimental study

Abstract Circular concrete-filled steel tubular (CFST) columns are widely used in civil engineering structures due to their high strength, stiffness, and ductility. However, these columns are susceptible to local corrosion damage, which can reduce their load-carrying capacity and durability. This paper presents an experimental investigation of the impact of local corrosion on the residual compressive strength of CFST stub columns. The experimental program included 9 CFST columns, which were divided into two groups: G1 and G2. G1 specimens were subjected to actual electrochemical corrosion, while G2 specimens were subjected to mechanical damage to simulate the corrosion effect. The experimental results included the tested columns’ corrosion profiles, failure modes, load-strain relationships, and load-carrying capacities. The main findings of this paper show that: (1) Different heights and thicknesses of corrosion profile representing the non-uniform localized corrosion. (2) Failure modes were mainly affected by the localized damage conditions, where the buckling occurred in the affected area. (3) Load-strain relationships exhibited elastic behavior initially, followed by nonlinear plastic behavior until reaching their ultimate compressive capacity. (4) The mechanical damage method can reasonably approximate the corrosion damage in CFST columns. This paper provides useful insights into the structural behavior of locally damaged CFST short columns.