Hoop Strain Research Articles

Cold-formed elliptical concrete-filled steel tubular columns subjected to monotonic and cyclic axial compression

Concrete-filled steel tubular columns are widely used in structural systems, and elliptical concrete-filled steel tubular columns are receiving more and more attention. An experimental study on cold-formed elliptical concrete-filled steel tubular stub columns was carried out under monotonic and cyclic axial compression. The failure modes, axial load–displacement curves, ultimate loads, hoop strain–axial strain behavior, strength deterioration, and residual deformation were obtained and discussed. Complementary finite element models considering the complex non-uniform confinement between steel tube and concrete were developed and validated by experimental results. Then, the validated FE model was used to study the influence of aspect ratio, yield strength of steel, and compressive strength of concrete on the axial capacity of elliptical concrete-filled steel tubular stub columns. Finally, a relatively simple superposition method was put forward to predict the axial bearing capacity of elliptical concrete-filled steel tubular stub columns. Compared with the test data, both the numerical method and superposition method can generate accurate predictions.

Hybrid-Fiber-Reinforced Concrete Used in Frozen Shaft Lining Structure in Coal Mines.

To address the cracking and leaking of concrete in frozen shaft linings in deep and thick topsoil layers in coal mines, hybrid-fiber-reinforced concrete (HFRC) was developed. First, the composition of the reference concrete was obtained by investigating high-strength concrete commonly used in shaft linings, and two dosages of polyvinyl alcohol fiber (PVAF) and polypropylene plastic steel fiber (PPSF) were obtained by the mixing test. Then, tests of early cracks of concrete were conducted; results showed that HFRC could almost avoid early cracks, exhibiting an advantage in early crack resistance. Thus, HFRC can play a significant role in improving the durability of frozen shaft linings in complex underground environments. Furthermore, a series of mechanical property tests were carried out. The results showed that the compressive strength of HFRC was similar to that of the reference concrete, but the tensile and flexural strength of HFRC was 42.7% and 35.1% higher than that of the reference concrete, respectively. Finally, an analog simulation model test of shaft linings was conducted. The new type of shaft lining structure containing hybrid fibers (HFs) exhibited plastic deformation characteristics under load, and the maximum hoop strain was −3562 με. It addressed the problem of high brittleness of frozen shaft lining structures of ordinary high-strength concrete and improved the toughness and crack resistance. HFRC is an ideal material for frozen shaft lining structures in deep and thick topsoil.

Biaxial Creep Behavior of Nb-Modified Zircaloys

Zirconium-niobium (Zr-Nb) alloys are used as cladding materials to encapsulate radioactive fuel in nuclear reactors. They possess excellent corrosion resistance at high temperatures making it possible to achieve high fuel burnup, directly increasing the thermal efficiency of the reactor. While they are commonly used in recrystallized (Rx) form in boiling water reactors, there is a need to understand the effect of cold work and stress relief (CWSR) on the biaxial creep characteristics of these materials due to their use in pressurized water reactors. In this study, the biaxial creep behaviors of as-received Zr-Nb alloys, HANA and Zirlo®, have been investigated at 500°C and 400°C, respectively, using internally pressurized tubing superimposed with axial load under varied hoop σθ to axial σz stress ratios of 0 to 2 while monitoring both the axial and hoop strains using a linear variable displacement transformer and a laser telemetric extensometer, respectively. The crystallographic textures and creep loci of these as-received Zr-Nb alloys have been evaluated to correlate with the previous studies on recrystallized HANA4 and CWSR Zircaloy-4. The creep locus of HANA4 was found to be unaffected by initial state (CWSR or Rx) and showed close correspondence to planar isotropy while the creep locus of CWSR Zirlo exhibited more resistance to axial deformation than diametrical as per CWSR Zircaloy-4 reported earlier. These differences are shown to arise from grain-shape anisotropy of the CWSR Zirlo and Zircaloy-4. The simulated creep loci using crystallite-orientation distribution functions in conjunction with prism slip models showed excellent agreement with experimental results.

A stress-path dependent stress-strain model for FRP-confined concrete

High-strength concrete (HSC) has higher strength-to-weight ratio and stiffness than normal-strength concrete (NSC). Therefore, the use of HSC can decrease the construction and demolition waste and embodied carbon content of structural members that enhances the urban sustainability. However, HSC is more brittle than NSC. To further push up the maximum concrete strength limit in practical construction, confining concrete by fibre-reinforced polymer (FRP) has been advocated to restore ductility. Compared with using hollow-steel tube as confinement, FRP has lighter weight, higher tensile strength, better corrosion resistance, and is more durable and flexible. Nevertheless, it is up to now a difficult task to predict accurately the uni-axial stress-strain behaviour of FRP-confined concrete since the effect of confining stress, concrete strength, hoop and axial strains are inter-related and need to be determined simultaneously. Herein, to better understand and simulate the behaviour of FRP-confined concrete, a stress-strain model has been developed, which consists of the following three main components: (1) A hoop strain equation elaborated from the authors’ previous study on steel-confined concrete columns for application to FRP-confined concrete; (2) A modified confined concrete model considering stress-path of confining stress (or history of hoop strain); (3) Interaction between FRP and concrete. The model was verified based on 321 test results obtained from the literature, the design application of the which to a broad range of FRP-confined concrete structures is thus ensured.

Nonlinear stability and buckling analysis of composite functionally graded arches subjected to external pressure and temperature loading

This paper investigates the nonlinear stability and buckling behavior of the composite functionally graded material (FGM) arches subjected to pressure and temperature loadings. By introducing an admissible displacement function, the total potential energy is expressed explicitly following the thin-walled shell theory. The nonlinear equilibrium equations are calculated by the variation of the potential energy function, and the critical buckling pressure is predicted analytically. The verification is taken by the numerical simulation that traces the pre- and post-buckling equilibrium paths, indicating that the numerical results are in good accordance with the analytical predictions. It is found the temperature rise increases the thermal upward displacement, which is beneficial to the buckling pressure, and reduces Young’s modulus, which is unbeneficial to the buckling pressure. Therefore, the buckling pressure is nonlinear to the temperature rise. Finally, a series of parametric evaluations are mainly focused on the effects of volume fraction exponent and temperature rise on the distributions of hoop strain, stress, force and bending moment.

Strength model of FRP confined concrete columns based on analytical analysis and experimental test

PurposeCovering a fiber-reinforced concrete column (fiber reinforced plastic (FRP)) improves the performance of the column primarily. The purpose of this paper is to investigate the behavior of small FRP concrete columns that are subject to axial pressure loading, in order to study the effect of many parameters on the effectiveness of FRP couplings on circular and square concrete columns.Design/methodology/approachThese parameters include the shape of the browser (circular and square), whole core and cavity, square radius of square columns, concrete strength (low strength, normal and high), type of FRP (carbon and glass) and number of FRP (1–3) layers. The effective fibrillation failure strain was investigated and the effect of effective lateral occlusion pressure.FindingsThe results of the test showed that the FRP-coated columns improved significantly the final conditions of both the circular and square samples compared to the unrestricted columns; however, improvement of square samples was not as prominent as improvement in circular samples. The results indicated that many parameters significantly affected the behavior of FRP-confined columns. A new model for predicting compressive force and the corresponding strain of FRP is presented. A good relationship is obtained between the proposed equations and the current experimental results.Originality/valueThe average hoop strain in FRP wraps at rupture in FRP-confined concrete specimens can be much lower than that given by tensile coupon tests, meaning the theoretical assumption that the FRP-confined concrete cylinder ruptures when the FRP material tensile strength attained at its maximum is not suitable. Based on this observation, the effective peak strength and corresponding strain formula for FRP concrete confined columns must be based on the effective hoop rupture strain composite materials.

The Effect of Heat Treatment and the Volume Fraction of the Alpha Phase on the Workability of Ti-5Al-5Mo-5V-3Cr Alloy

Ti-5Al-5Mo-5V-3Cr (Ti-5553) is a metastable beta titanium alloy with high hardenability, good ductility, and high strength. Different microstructures with different volume fractions and distribution of α phase can be produced in this alloy by suitable heat treatment. In this study, the workability of this alloy has been determined as a function of the volume fraction of α phase in the microstructure. Workability is an important parameter indicating the ability of the material to be deformed without the occurrence of fracture. Specimens with three different volume fractions of alpha phase were produced using suitable heat treatments. Two different volume fractions of α (approx 3 and 23%) were obtained by air and furnace cooling, respectively, after solutionizing at 877 °C, i.e., 25 °C above the beta transus temperature. The third specimen with approximately 18% volume fraction of α was obtained by solutionizing at 800 °C for 4 h, followed by water quenching. Workability was investigated by conducting upsetting tests on cylindrical specimens with varying height-to-diameter ratios. Workability limit diagrams have been obtained as a function of axial and hoop strains at fracture. The workability for the furnace cooled specimens was found to be very poor compared to the other two specimens. The results were evaluated using four popular ductile fracture criteria, and the values of critical damage constants at fracture initiation have been calculated using the experimental upsetting test data. The theoretical fracture strains were estimated using the critical constants obtained for all the four ductile fracture criteria and were compared with experimental test data. The Cockroft and Latham, Brozzo et al., and Oh et al. showed close agreement with the experimental values and therefore can be used as ductile fracture criteria for this alloy.

Study on the active confinement of GFRP-confined expansive concrete under axial compression

Glass fiber reinforced polymer (GFRP) based tubes provide good passive confinement to enhance structural capacity and ductility. Literature has demonstrated that introduction of the expansive agent in the concrete mixture provides the active confinement on the structures. Thus, this study is to explore the axial compression behavior of GFRP-confined expansive concrete cylinders. Eighteen GFRP-confined concrete cylinders, including nine expansive concrete (EG) and nine conventional concrete (or called ordinary concrete, OG) as a reference were cast and then loaded by axial compression. Compared with conventional concrete mixture, the expansive concrete produces a certain active confinement on the peripheral FRP tube due to expansion of concrete and confinement of GFRP. Experimental results indicate that, due to the confinement effect of FRP and expansion of core concrete, the hoop strain reduction factor, normalized stress at inflection points, the compressive strength and ultimate axial strain of the EG specimens were all improved compared with OG specimens. Moreover, the axial stress-strain model was formulated based on the modification of the unified equations in the literature to account for active confinement effects generated by expansive agent. A comparison indicated that the analytical model captured well with the whole load history, and the predicted data were well consistent with the experimental data.

OFBG-Based Smart Double-Skin Tubular Confined-Concrete Column with Basalt FRP-Steel Composite.

Fiber-reinforced polymer (FRP) composites have been widely employed to design advanced structural columns such as the hybrid FRP–concrete–steel double-skin tubular column (hybrid DSTC) with potential benefits. To date, the safety and self-monitoring of the hybrid DSTCs are still a challenge to overcome due to the complex damage scenarios. This paper investigates the self-sensing performance of a newly developed smart double-skin tubular confined concrete column (smart BFST-DSTC) made of basalt FRP–steel composite with built-in optical fiber Bragg grating sensors (OFBGs). The design of the smart BFST-DSTC and sensing principle are firstly addressed, followed by an experimental investigation on the basic mechanical properties and strain-based sensing performance of ten scaled specimens under axial compression. The outcomes reveal the enhancement of the proposed column in terms of load-carrying capacity, confinement ratio, and axial stress-axial strain behavior, as well as failure and damage modes when compared with the hybrid DSTC. The self-sensing investigation demonstrates that the measurement range satisfies the requirement to monitor and evaluate the hoop strains of the FRP jackets and the health state of the inner tube. The smart BFST-DSTC can replace the hybrid DSTC with the ability to provide early failure warning and life cycle health monitoring.

Collapse mechanism of the thin-walled functionally graded cylinders encased in the saturated permeable mediums

This paper investigates the stability behavior of the thin-walled functionally graded material (FGM) cylinders encased in the saturated permeable mediums. Water pressure generates at the outer surface of the cylinder, resulting in “single-lobe” or “two-lobe” deformations due to the confinement of the medium. The critical buckling pressure of the FGM cylinder is obtained analytically by exploring the total potential energy function. It is found that the two-lobe deformation sustains a higher pressure capacity than the single-lobe deformation. A two-dimensional (2D) finite element model (FEM) is developed to obtain the maximum pressure (buckling pressure) by plotting the pressure-displacement equilibrium curves. The comparison shows that the analytical solutions are in very close agreement with the numerical results in terms of the buckling pressure, as well as the equilibrium paths. Finally, the effect of volume fraction exponent (n) on the hoop strain, stress, force and bending moment through the cylinder wall is fully examined, indicating the non-symmetrical distribution of the material properties to the mid-surface of the FGM cylinder has a significant influence on the buckling pressure.

Analytical consideration and numerical verification of the confined functionally graded porous ring with graphene platelet reinforcement

The present work is concerned with the stability behavior of the functionally graded porous (FGP) ring with graphene platelet (GPL) reinforcement. The ring is surrounded by an elastic medium and a point load is introduced at the crown position. Assuming no interface friction between the ring and medium, the buckling load of the ring with a “single-lobe” deformation is obtained analytically. Afterward, the numerical examination is developed by comparing the critical buckling load from the numerical and analytical results. The good comparison indicates the analytical solutions are applicable to the nine cases by combining three porous distributions and three GPL dispersion patterns, respectively. It is explored that the combination of symmetrical pores and symmetrical GPL to the mid-surface can resist the highest external load of the confined FGP–GPL ring, and this case is successfully compared with other closed-form expressions for the homogeneous ring without pores and GPL. Finally, the effects of porosity coefficient, and weight fraction of the GPL are examined and discussed in terms of the load capacity, the hoop force, the bending moment, the hoop stress and strain, and the geometric shapes of the GPL.

Centrifuge Testing of Circular and Rectangular Embedded Structures with Base Excitations

We present data and metadata from a centrifuge testing program that was designed to investigate the seismic responses of buried circular and rectangular culverts. The specimen configurations were based on Caltrans Standard Plans, and the scope of research was to compare the experimental findings with the design method described in the NCHRP Report 611 as well as to formulate preliminary recommendations for Caltrans practice. A relatively flexible pipe and a stiff box-shaped specimen embedded in dense sand were tested in the centrifuge at the Center for Geotechnical Modeling at University of California, Davis and were subjected to a set of broadband and harmonic input motions. Responses were recorded in the soil and in the embedded structures using a dense array of instruments. Measured quantities included specimen accelerations, bending strains, and hoop strains; soil accelerations, shear-wave velocities, settlements, and lateral displacements; and accelerations of the centrifuge's shaking table. This data paper describes the tests and summarizes the generated data, which are archived at DesignSafe.ci.org (DOI: 10.17603/DS2XW9R) and are accessible through an interactive Jupyter notebook.

Design of Strain-Limited Bi-2223 Insert Coils for High-Field Magnets

High field solenoid coils made with HTS conductors are limited primarily by total strain and then by critical current. A detailed accounting of all the sources of mechanical strain on a coil is an essential part of the design. Those sources include winding tension, bending about the coil axis, bending to form the layer transition, compression from overbanding, differential thermal contraction, magnetic hoop strain in the radial and axial directions, and thermal expansion from quenches. A design example for a high-field insert coil made with Sumitomo Type HT-NX Bi-2223 conductor is presented, with each of the relevant strains computed explicitly.

Stress and strain analysis of a REBCO high field coil based on the distribution of shielding current

There are growing concerns about the stresses created by shielding currents in high field superconducting magnets fabricated from tape conductors leading to reduced performance and lifetime. This paper presents results of stress/strain calculations caused by shielding currents assuming the conductor deformations follow a linear constitutive relation. An anisotropic bulk approximation approach was used to calculate the electromagnetic field distributions in a REBCO high field coil with a stack of pancakes and a large number of turns first, and then the Lorentz force distribution and mechanical response characteristics were studied in the two-dimensional axisymmetric configuration. A new discrete contact mechanical model implemented by the finite element method, which is able to simulate the contact and separation behaviors between adjacent turns during the deformation, was proposed to analyze the distributions of hoop stress, hoop strain, radial stress and radial displacement in the coil. The influences of shielding current on those mechanical responses were obtained by comparing the simulation cases with and without taking shielding current into account. Besides, a continuum bulk mechanical model, which is parallel to the discrete contact mechanical model and treats the pancakes as continuum bulks, was modeled as well in order to understand the influences of different models on the simulation results. Furthermore, we studied the influences of a couple of practical factors (including the -value, ramp rate, and operating mode of the REBCO coil winding) on the shielding current and hoop stress. A couple of novel and important conclusions were found. (1) Neglecting the shielding current behavior would significantly underestimate the maximum local hoop stress in a REBCO high field coil. (2) The continuum bulk mechanical model is not adequate for the stress analysis of dry-wound high field coils, by which unreasonably large tensile radial stresses could be obtained. (3) The highest local hoop stresses at the fully-charged moment and the fully-discharged moment are located in a certain pancake near the end of the coil winding and the end pancake, respectively. (4) Decreasing the -value and the ramp rate of the REBCO coil could be two auxiliary ways to suppress the shielding current and maximum local hoop stress in the coil. (5) For the ramp-and-hold operating mode, the REBCO coil experiences the highest stress level at the moment when it right achieves the goal field. (6) The cycling operation of a REBCO high field coil can cause the tape experiencing alternative positive and negative hoop stresses and this may decrease the fatigue life of the tape and then the life of a magnet.

Multipoint hoop strain measurement based pipeline leakage localization with an optimized support vector regression approach

Pipelines are used to carry fluids across long distances. Given the costly and hazardous nature of some of these fluids, timely and accurate inspection for damages is imperative to prevent harmful financial and environmental consequences. In the previous research, a fiber optic based hoop strain sensor is developed and reported to accomplish the goal of pipeline corrosion and leakage monitoring. The sensors form a foundation upon which advanced damaged detection algorithms can be carried out. In this paper, the application of distributed hoop strain sensing information combined with support vector regression (SVR) is demonstrated to pinpoint leakage position on a long-distance pressurized pipeline. The SVR parameters were further optimized by a genetic algorithm (GA) in order to improve accuracy. The resulting leakage detection system had a mean squared error as low as 0.076 when no noise was present. The effect of noise (approximated by Gaussian white noise) was studied in a simulation, showing an effective 5% error for a 55 km simulated pipeline. Results also showed that the use of more sensors corresponded to heightened robustness towards different noise levels.

Behaviour of CFRP wrapped RC square columns under eccentric compressive loading

This paper presents the effects of carbon fibre reinforced polymer (CFRP) volumetric ratios on structural and failure behaviour of CFRP wrapped reinforced concrete (RC) square columns under concentric, eccentric and flexural loadings. The CFRP volumetric ratio is considered as the ratio of volume of CFRP to the volume of concrete. The applicability of existing confinement models to predict the load-moment interaction diagrams of such columns in eccentric loadings is also presented in this paper. Total 20 columns were tested. Dimensions of all columns were 175x175x800 mm with 20 mm rounded corners. Variable considered in this study were number of CFRP layers (e.g. 0, 1, 2 and 3 layers) which corresponds to CFRP volumetric ratio of 0, 0.3, 0.6 and 0.9%, respectively, increasing eccentricities (e.g. 0, 25, 35 and 50 mm) of the applied load and pure flexural loading. Results show that ultimate load capacity and axial deformation increase with increase in CFRP volumetric ratios irrespective of eccentricities. However, load capacity and deformation decrease with increasing eccentricities for any given CFRP volumetric ratio. Hoop strains also increase with increase in CFRP volumetric ratios and eccentricities. Stiffness of CFRP wrapped columns also increases with increase in CFRP volumetric ratio up to 0.6% and decreases with increase in eccentricities. Ductility of CFRP wrapped columns increases with increase in CFRP volumetric ratios and eccentricities. The algorithms for calculation of critical points for load-moment (P-M) interaction diagrams using analytical as well as numerical stress integrations are developed and compared to those of the column tests. P-M interaction diagram developed using existing confinement models agree well with the experimental P-M interaction diagrams of CFRP wrapped RC square columns under eccentric loading.

Anisotropic crack propagation and deformation in dentin observed by four-dimensional X-ray nano-computed tomography

Understanding the cracking behaviour of biological composite materials is of practical importance. This paper presents the first study to track the interplay between crack initiation, microfracture and plastic deformation in three dimensions (3D) as a function of tubule and collagen fibril arrangement in elephant dentin using in situ X-ray nano-computed tomography (nano-CT). A nano-indenter with a conical tip has been used to incrementally indent three test-pieces oriented at 0°, 45° and 70° to the long axis of the tubules (i.e. radial to the tusk). For the 0° sample two significant cracks formed, one of which linked up with microcracks in the axial-radial plane of the tusk originating from the tubules and the other one occurred as a consequence of shear deformation at the tubules. The 70° test-piece was able to bear the greatest loads despite many small cracks forming around the indenter. These were diverted by the microstructure and did not propagate significantly. The 45° test-piece showed intermediate behaviour. In all cases strains obtained by digital volume correlation were well in excess of the yield strain (0.9%), indeed some plastic deformation could even be seen through bending of the tubules. The hoop strains around the conical indenter were anisotropic with the smallest strains correlating with the primary collagen orientation (axial to the tusk) and the largest strains aligned with the hoop direction of the tusk. Statement of SignificanceThis paper presents the first comprehensive study of the anisotropic nature of microfracture, crack propagation and deformation in elephant dentin using time-lapse X-ray nano-computed tomography. To unravel the interplay of collagen fibrils and local deformation, digital volume correlation (DVC) has been applied to map the local strain field while the crack initiation and propagation is tracked in real time. Our results highlight the intrinsic and extrinsic shielding mechanisms and correlate the crack growth behavior in nature to the service requirement of dentin to resist catastrophic fracture. This is of wide interest not just in terms of understanding dentin fracture but also can extend beyond dentin to other anisotropic structural composite biomaterials such as bone, antler and chitin.

Axial Compression Behaviour of Hybrid Double-Skin Tubular Columns Filled with Rubcrete

Double-skin tubular columns (DSTCs) have become a competitive candidate for column members due to their important advantages compared with conventional reinforced concrete columns, including their better weight-to-strength ratio and ease of construction. Using Rubcrete in hybrid DSTCs is of great interest due to the potential of this system to overcome the Rubcrete material deficiencies and to add more ductility, toughness, seismic resistance, confinement effectiveness, and environmentally-friendly features to that structural system compared to conventional concrete. In this paper, hybrid DSTCs made out of Rubcrete, sandwiched between a fibre reinforced polymer (FRP) tube and a steel tube, were tested. The examined variables were concrete sand or stone replacement ratio (0% and 20%), FRP wall thickness (1- and 2-layers), steel wall thickness (3.2 mm and 4.5 mm), void ratio (50% and 76%), and void shape (circular or square). The axial and lateral stress–strain responses were monitored, measured, and compared. According to this investigation, using Rubcrete in hybrid DSTCs can enhance the axial and hoop strain capacities, especially with fine rubber particles. It was also observed that the adverse influence of using rubber on column ultimate capacity was much lower in DSTC specimens, compared with that of unconfined Rubcrete columns. Therefore, using Rubcrete with fine rubber particles is recommended in DSTC structural columns.

Inflation and rupture of vaginal tissue.

Around 80% of women experience vaginal tears during labour when the diameter of the vagina must increase to allow the passage of a full-term baby. Current techniques for evaluating vaginal tears are qualitative and often lead to an incorrect diagnosis and inadequate treatment, severely compromising the quality of life of women. In order to characterize the failure properties of the vaginal tissue, whole vaginal tracts from rats (n = 18) were subjected to free-extension inflation tests until rupture using a custom-built experimental set-up. The resulting deformations were measured using the digital image correlation technique. Overall, the strain and changes in curvature in the hoop direction were significantly larger relative to the axial direction. At a failure pressure of 110 ± 23 kPa (mean ± s.d.), the hoop and axial stresses were computed to be 970 ± 340 kPa and 490 ± 170 kPa, respectively. Moreover, at such pressure, the hoop and axial strains were found to be and , respectively. Rupture of the vaginal specimens always occurred in the hoop direction by tearing along the axial direction. This knowledge about the rupture properties of the vaginal tissue will be crucial for the development of clinical approaches for preventing and mitigating vaginal tearing and the associated short- and long-term traumatic conditions.

Combined Study on Mold Taper and Corner Radius in Bloom Continuous Casting by FEM Simulation and Trial Experiment

A plane stress model was developed to study the coupled effect of mold taper and corner radius on the thermal–mechanical behavior of a 250 mm × 280 mm continuously cast bloom for a given special steel. Good agreement was obtained in both shell thickness and the off-corner cracking location from modeling and trial experiment. The results show that increasing mold taper results in the obvious decrease of surface temperature near the corner, while enlarging mold corner radius makes the shell surface temperature at the corner region more even with the mold taper between 0 and 1.5% m−1. It is also found that both the mold corner radius and taper are the key factors influencing the shell crack sensitivity but with different mechanism. For the internal crack, the mold taper takes more dominant effect for its corner radius between 0–10 mm, as the hoop strain at the solidification front decreases with increasing mold taper. For the surface crack, more sensitivity is noticed to the mold corner radius. Increasing mold corner radius leads to the increase of the surface hoop strain in the corner region, almost regardless of mold taper. The proper mold taper and corner radius for the present bloom casting should be 1.0–1.5% m−1 and 15–25 mm respectively.