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The lack of ductility is known to be one of the major drawbacks of amorphous state. Recently, an increase in the tensile strength and ductility was found in the ${\text{Ni}}_{82.1}$${\text{Cr}}_{7.8}$${\text{Si}}_{4.6}$${\text{Fe}}_{3.1}$${\text{Mn}}_{0.2}$${\text{Al}}_{0.1}$${\text{Cu}}_{0.1}$B₂ metal glass ribbon pre-annealed at $\beta$-relaxation temperature. This paper analyzes the surface relief transformation observed during this process and the nature of separate inhomogeneities. The most significant effect is a flattening of the surface relief. This case was confirmed by statistical processing. Thus, the surface relief change was shown to be a clear indicator of structure relaxation process, that occurs in a metal glass ribbon well below its crystallization.

Two catastrophic earthquakes occurred in the Eastern Anatolian Fault Zone on February 6, 2023, in the city Kahramanmaraş in Türkiye and directly affected the Eastern and South-Eastern Anatolia regions, where 15 million people live. These earthquakes are among the most destructive earthquakes in the history of Türkiye and destroyed both old and new structures. While many studies have been conducted to report the caused damage in the existing building stock, common damage is worth in-depth discussion since it was observed in the seismic code-compliant new buildings. This damage is the buckling of compression reinforcement (BCR) in reinforced concrete beams. In this study, the observed damage mechanism has been evaluated with the design requirement of the recent seismic codes of Türkiye. The principles of anti-buckling design requirements in literature were searched and a certain deficiency in the codes was revealed. The outcomes of the study have been applied to an existing newly constructed reinforced concrete building that experienced BCR damage in its beam. It has been demonstrated that beams designed according to Türkiye’s recent seismic codes may fail to reach the ductility level specified in the literature due to buckling of their compression bars under extreme loading.

The elastic constants are paramount to determine the strength of alloys. The elastic constants of $M$–Ir, $M_3$–Ir, and $M$–Ir₃ where $M$ represents $\mathrm{\text{Cu}}$, $\mathrm{\text{Au}}$, $\mathrm{\text{Ni}}$, $\mathrm{\text{Ag}}$, $\mathrm{\text{Pt}}$, $\mathrm{\text{Al}}$, $\mathrm{\text{Pd}}$ and $\mathrm{\text{Rh}}$ were computed at room temperature using the embedded atom method (EAM) and the alloy mixing potentials. The potential parameters of the selected pure metals were fitted to the experimental values to compute some properties of Ni–Al, Ni₃–Al, Ni–Al₃, Cu–Au, Cu₃–Au and Cu–Au₃, and by comparing the experimental data with our predictions, the employed potential predicted some results in reasonable agreement to available experimental data with discrepancies in some cases, and these discrepancies linked to the dependence of the computed elastic constants on the fitting parameters. The potential with the metallic parameters was used as alloy parameters in computing the elastic constants, bulk modulus, and the shear modulus of the iridium binary alloy. It was generally observed that, the selected metals improve the ductility of Iridium with the highest value, recorded for Pd–Ir, and consequently the minimum value for Al–Ir, and Rh–Ir which characterized them to be ductile. The balance orders for the binary alloys were provided through the formation enthalpy.

Cu-based bulk metallic glasses are of relative low cost and high strength. They have more potential to be used as engineering materials. However, the lack of ductility has largely limited their applications. In the last few years, attempts have been made to form Cu-based BMG composites with two-phase microstructure to improve the ductility of BMGs, including extrinsic composites, in-situ composites and nanocrystalline composites. In this paper, two in-situ BMG composites have been successfully prepared with TiC and Ti₂B particles respectively in-situ formed in the Cu-based BMG matrix. After the introduction of the TiC and Ti₂B particles, besides of the lineal increase of hardness, the materials exhibit significant plasticity.

In order to study the mechanism of decreasing tensile strength and elongation of Austempered Ductile Cast Iron (ADI) in the wet condition, various tension tests and impact tests were carried out. Three point bending fatigue tests were carried out on ADI and annealed 0.55% carbon steel to clarify the influence of water on fatigue strength. The main conclusions are as follow. Embrittlement by water begins when plastic deformation starts in a tension test. The fatigue limit of ADI in water showed a lower value than that in air. The influence of a water environment on fatigue behaviour was similar to that of annealed 0.55% carbon steel. Embrittlement such as that in a tension test was not observed in a fatigue test.

The ab initio computations have been performed to examine the structural, elastic, electronic and phonon properties of cubic $\mathrm{\text{La}}X$$(X=\mathrm{\text{Cd}}$, $\mathrm{\text{Hg}}$ and $\mathrm{\text{Zn}})$ compounds in the $B2$ phase. The optimized lattice constants, bulk modulus, and its pressure derivative and elastic constants are evaluated and compared with available data. Electronic band structures and total and partial densities of states (DOS) have been derived for $\mathrm{\text{La}}X$$(X=\mathrm{\text{Cd}}$, $\mathrm{\text{Hg}}$ and $\mathrm{\text{Zn}})$ compounds. The electronic band structures show metallic character; the conductivity is mostly governed by $\mathrm{\text{La}}$-$5d$ states for three compounds. Phonon-dispersion curves have been obtained using the first-principle linear-response approach of the density-functional perturbation theory. The specific heat capacity at a constant volume $C_V$ of $\mathrm{\text{La}}X$$(X=\mathrm{\text{Cd}}$, $\mathrm{\text{Hg}}$ and $\mathrm{\text{Zn}})$ compounds are calculated and discussed.

The Ni–Cr–Fe metal powder was deposited on EA4T steel by laser cladding technology. The microstructure and chemical composition of the cladding layer were analyzed by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The bonding ability between the cladding layer and the matrix was measured. The results showed that the bonding between the cladding layer and the EA4T steel was metallurgical bonding. The microstructure of cladding layer was composed of planar crystals, columnar crystals and dendrite, which consisted of Cr₂Ni₃, $\gamma$ phase, M${}_{23}$C₆ and Ni₃B phases. When the powder feeding speed reached 4 g/min, the upper bainite occurred in the heat affected zone (HAZ). Moreover, the tensile strength of the joint increased, while the yield strength and the ductility decreased.

The ab-initio calculations based on the density functional theory (DFT) have been performed to study the structural, mechanical, electronic, thermal and thermodynamic properties of Al₃Sc and Al₃Ti binary compounds and their ternary mixture Al₃(Sc${}_{1-x}$Ti${}_x$) in L1₂ and D0${}_{22}$ structures. The total energy calculations show that the L1₂ structure is the more stable one. The Al₃Sc${}_{0.25}$Ti${}_{0.75}$ undergoes a martensitic transformation and the formation enthalpies and the lattice parameters decrease with increasing concentration x. The elastic constants are determined and the results show that all compounds are mechanically stable and the cubic cells are more easily deformed by shearing than by unidirectional compression. The elastic modulus indicates that the addition of Ti atoms to Al₃Sc improves its ductility. The densities of states (DOSs) calculations show the strong spd hybridization which leads to the formation of a pseudo-gap near the Fermi level in ternary alloys. The densities of states at the Fermi level N(E${}_F$) confirm the phase stability. The quasi-harmonic Debye model is used to predict the thermal properties such as heat capacity, Debye temperature, Grüneisen parameter and thermal expansion coefficient of the considered alloys. The determination of Gibbs free mixing energy at different concentrations has been used to calculate the T–x diagram.

The mechanical, electronic and thermodynamic properties of Pd₃M (M=Sc, Y) compounds have been investigated using the Full Potential Linearized Augmented Plane Wave (FP-LAPW) formalism. The generalized gradient approximation (GGA) is used to treat the exchange–correlation terms. The calculated formation enthalpies and the cohesive energies reveal that the L1₂ structure is more stable than the D0${}_{24}$ one. The obtained lattice parameters and bulk modulus calculations conform well to the available experimental and theoretical results. The elastic and mechanical properties are analyzed and results show that both compounds are ductile in nature. The Debye temperature and melting temperature are also estimated and are in a good agreement with experimental findings. The total and partial densities of states are determined for L1₂ and D0${}_{24}$ structures. The density of states at the Fermi level, $N$($E_{\mathrm{\text{F}}}$), indicates electronic stability for both compounds. The presence of the pseudo-gap near the Fermi level is suggestive of formation of directional covalent bonding. The number of bonding electrons per atom $n_b$ and the electronic specific heat coefficient $\gamma$ are also determined. The quasi-harmonic Debye model has been used to explore the temperature and pressure effects on the thermodynamic properties for both compounds.

In this paper, site preference, phase stability and elastic parameters of MoSi₂ for Al and Nb addition are studied using first-principles calculation. The results show that alloying elements can cause MoSi₂ to change from C11_b to C40 phase and the phase transition is due to the activated 1/2[$\bar{1}$11](110) slip system for C11_b. $G∕B$ ratio reveals that the ductility is enhanced after phase transition. Ductile factor ${\sigma }_{{\gamma }_m}∕{\sigma }_c$ based on competitive processes between micro-crack opening and dislocations emission is defined to assess the ductility of MoSi₂. Interestingly, the increased ductility is due to the activated dislocation emission but suppressed crack propagation. Finally, charge density and DOS indicate that the improved ductility is due to the weakened Mo-4d and Si-3p covalent interactions.

The effect of rolling parameters on microstructure and tensile properties of nanocrystalline/microcrystalline 304 stainless steel (SS) casted by the aluminothermic reaction was investigated in this work. It was found that majority of the nanocrystalline austenite of the 304 SS rolled at 700${}^{\circ }$C and 900${}^{\circ }$C grew up and transformed to sub-microcrystalline. While the nanocrystalline/microcrystalline structure still retained rolled at 900${}^{\circ }$C with 40% deformation followed 600${}^{\circ }$C with 70% thickness reduction, and microcrystalline austenite grains distributed evenly. The strength and ductility of the various rolled 304 SS were improved compared with the as-casted 304 SS steel. The steel rolled at 900${}^{\circ }$C with 80% deformation exhibited a uniform elongation as large as 31.3%, which is almost the same ductility level of counterpart coarse-grained steel. The rolled steel at 700${}^{\circ }$C with 80% deformation achieved the maximum tensile strength but the smallest elongation. The sample, two-step rolled at 900${}^{\circ }$C with 40% thickness reduction and then 600${}^{\circ }$C with 70% thickness reduction, yielded the satisfactory combination of strength and ductility. The yield strength and elongation were appropriate 767 MPa and 22.8%, respectively, which resulted from the optimized nanocrystalline/microcrystalline structure and distribution.

The concept of equivalent linearization is extended for the soil-structure systems, in which the strength ratio (defined as the ratio of the yielding strength to the elastic strength demand) is known rather than the ductility ratio. The nonlinear soil-structure system is replaced by a linear single-degree-of-freedom (SDOF) system, which can capture the response of the actual system with sufficient accuracy. The dynamic characteristics of the equivalent linear SDOF system are determined through a statistical approach. The super-structure is modeled by an inelastic SDOF system with bilinear behavior, and the homogeneous half space beneath the structure by a discrete model, following the Cone Model. To cover a wide range of soil-structure systems, a comprehensive parametric study is conducted using a set of nondimensional parameters for the soil-structure system. The accuracy of the equivalent linear parameters is then assessed. The results confirm that the proposed equivalent linear model can capture the simultaneous effects of soil-structure interaction (SSI) and nonlinearity in the super-structure concerning the maximum inelastic response of the soil-structure system.

The previously formulated model of the gravity-driven collapse of the twin towers of the World Trade Center (WTC) on September 11, 2011 was shown to match all the existing observations, including the video record of the crush-down motion of the top part of tower during the first few seconds, the seismically recorded duration of collapse, the size distribution of particles caused by impact comminution of concrete floor slabs, the loud booms due to near-sonic lateral ejection velocity of air and dust, and precedence of the crush-down collapse mode before the crush-up. Nevertheless, different degrees of ductility, fracturing and end support flexibility of WTC columns could lead to an equally good match of these observations and remained uncertain, due to lack of test data. Recently, Korol and Sivakumaran reported valuable experiments that allow clarifying this uncertainty. They revealed that, under the simplifying assumptions of rigid end supports and unlimited ductility (or no fracturing) of unheated columns, the energy dissipation of the WTC columns would have been at maximum 3.5-times as large as that calculated by the plastic hinge mechanism normally considered for small-deflection buckling. This increase would still allow close match of all the aforementioned observations except for the first two seconds of the video. The proper conclusion from Korol and Sivakumaran’s tests, based on close matching of the video record, is that the fracturing of unheated columns and the flexibility of their end restraints must have significantly reduced the energy dissipation in columns calculated under the assumptions of no fracture and no end restraint flexibility.

The complexity in nonlinear behavior of torsional-irregular buildings in combination with uncertainty due to the natural randomness of earthquake records has been always a main challenge for buildings’ seismic design. To find a solution to this challenge, three reinforced concrete (RC) building archetypes were designed and next developed into their nonlinear models. Nonlinear static (pushover) analyses were performed to calculate the capacity of the archetype models in all principal and non-principal directions while incremental dynamic analyses (IDAs) were conducted by applying 30 accelerograms from both near-field and far-field earthquakes. The IDA capacity curves, collapse fragility curves and log-normal cumulative distribution functions (CDFs) were established by including both the aleatory randomness and epistemic uncertainty. Despite previous studies wherein fragility curves were given by evaluating structures’ collapse along structural reference axes or simply on $x$, $y$-axes, in this paper, possible building collapse on a critical non-principal direction (where maximum seismic response was observed) was simulated and its probability was accounted for developing IDA curves and log-normal CDFs. Accordingly, this issue was mirrored in computing available/acceptable collapse margin ratios (CMRs). In addition to the well-known outline used for calculating CMRs in the literature (that is based on estimation of collapse capacity in terms of earthquake intensity measure (IM)), the framework proposed here includes a new method for calculating the CMRs in terms of displacement-based drift, ductility, and damage. The superiority of the proposed method over the former is consistent with the buildings’ design procedure that is governed by storey drift control rather than base-shear strength. Refined statistics of CMRs given by taking into account displacement-based responses illustrate the available CMRs exceed the acceptable CMRs, meaning that a satisfactory safety margin against collapse will be anticipated in the targeted building class if a suitable yielding mechanism with sufficient ductility is provided for seismic force-resisting system by applying seismic design provisions of the current codes.

The role of soil-structure interaction (SSI) in the seismic response of structures is reexplored using recorded motions and theoretical considerations. Firstly, the way current seismic provisions treat SSI effects is briefly discussed. The idealised design spectra of the codes along with the increased fundamental period and effective damping due to SSI lead invariably to reduced forces in the structure. Reality, however, often differs from this view. It is shown that, in certain seismic and soil environments, an increase in the fundamental natural period of a moderately flexible structure due to SSI may have a detrimental effect on the imposed seismic demand. Secondly, a widely used structural model for assessing SSI effects on inelastic bridge piers is examined. Using theoretical arguments and rigorous numerical analyses it is shown that indiscriminate use of ductility concepts and geometric relations may lead to erroneous conclusions in the assessment of seismic performance. Numerical examples are presented which highlight critical issues of the problem.

An analytical solution is presented for the response of a bilinear inelastic simple oscillator to a symmetric triangular ground acceleration pulse. This type of motion is typical of near-fault recordings generated by source-directivity effects that may generate severe damage. Explicit closed-form expressions are derived for: (i) the inelastic response of the oscillator during the rising and decaying phases of the excitation as well as the ensuing free oscillations; (ii) the time of structural yielding; (iii) the time of peak response; (iv) the associated ductility demand. It is shown that when the duration of the pulse is long relative to the elastic period of the structure and its amplitude is of the same order as the yielding seismic coefficient, serious damage may occur if significant ductility cannot be supplied. The effect of post-yielding structural stiffness on ductility demand is also examined. Contrary to presently-used numerical algorithms, the proposed analytical solution allows many key response parameters to be evaluated in closed-form expressions and insight to be gained on the response of inelastic structures to such motions. The model is evaluated against numerical results from actual near-field recorded motions. Illustrative examples are also presented.

Recent studies provided opportunities to review some of the principles, which have been used in the formulations of internationally accepted code-recommendations relevant to the seismic design of ductile buildings also subjected to torsional phenomena. With the progress of this study, features emerged which are considered to have contributed to a better understanding of structural behaviour. Moreover, the identification of deeply embedded fallacies, relevant to ductile response, suggested the introduction of some changes in seismic design strategies, yet not widely known or appreciated. Reasons for necessary re-interpretations of traditional structural properties, together with illustrative examples, demonstrating applications, rather than set code-type rules, are offered.

A seismic design procedure for partially concrete-filled box-shaped steel columns is presented in this paper. To determine the ultimate state of such columns, concrete and steel segments are modelled using beam-column elements and a pushover analysis procedure is adopted. This is done by means of a new failure criterion based on the average strain of concrete and steel at critical regions. The proposed procedure is applicable to columns having thin- and thick-walled sections, which are longitudinally stiffened or not. An uniaxial constitutive relation recently developed is employed for concrete filled in the thick-walled unstiffened section columns. Modifications are introduced to this model for other types of columns. Subsequently, the strength and ductility predictions obtained using the present and previous procedures are compared with the corresponding experimental results. Comparisons show that the present procedure yields better predictions. It is revealed that the inclusion of the confinement effects and softening behaviour of concrete is important in the present kind of prediction procedures. Furthermore, an extensive parametric study is carried out to examine the effects of procedures and geometrical and material properties on capacity predictions.

A comprehensive study is undertaken to assess and calibrate the force reduction factors (R) adopted in modern seismic codes. Refined expressions are employed to calculate the R factors "supply" for 12 buildings of various characteristics represent a wide range of medium-rise RC buildings. The "supply" values are then compared with the "design" and "demand" recommended in the literature. A comprehensive range of response criteria at the member and storey levels, including shear as a failure criterion, alongside a detailed modelling approach and an extensively verified analytical tool are utilised. A rigorous technique is employed to evaluate R factors, including inelastic pushover and incremental dynamic collapse analyses employing eight natural and artificial records. In the light of the information obtained from more than 1500 inelastic analyses, it is concluded that including shear and vertical motion in assessment and calculations of R factors is necessary. Force reduction factors adopted by the design code (Eurocode 8) are over-conservative and can be safely increased, particularly for regular frame structures designed to lower PGA and higher ductility levels.

The results of some simulated seismic load tests on reinforced concrete one-way interior and exterior beam-column joints with substandard reinforcing details typical of buildings constructed in New Zealand before the 1970s are described. The tests were conducted using both deformed and plain round longitudinal reinforcement. The interior beam-column joint cores lacked transverse reinforcement and the longitudinal bars passing through the joint core were poorly anchored. The exterior beam-column joint units contained very little transverse reinforcement in the members and in the joint core. In one exterior beam-column joint unit the beam bar hooks were not bent into the joint core. That is, the hooks at the ends of the top bars were bent up and the hooks at the ends of the bottom bars were bent down. This anchorage detail was common in many older buildings constructed before the 1970s. In the other exterior beam-column joint unit the hooks at the ends of the bars were bent into the joint core as in current practice. The improvement in performance of the joint with beam bars anchored according to current practice is demonstrated. In addition, tests were conducted on interior joints with lap splices in the beam longitudinal reinforcement bars near the column face. The tests were conducted using both deformed and plain round longitudinal reinforcement. Tests were also conducted on columns with plain round bar longitudinal reinforcement and inadequate transverse reinforcement.

The reinforcing details were close to identical to those in an existing seven storey reinforced concrete building that was designed and built in New Zealand in the late 1950s.

The test results give an indication of the performance of beam-column joints and members with the above now out-of-date reinforcing details.

The test results reported are a summary of results reported in a number of publications written since 1994.