Collapse Point Research Articles

Mass Inflation without Cauchy Horizons.

Mass inflation is a well established instability, conventionally associated to Cauchy horizons (which are also inner trapping horizons) of stationary geometries, leading to a divergent exponential buildup of energy. We show here that finite (but often large) exponential buildups of energy are present for dynamical geometries describing accreting black holes with slowly evolving inner trapping horizons, even in the absence of Cauchy horizons. The explicit evaluation of the adiabatic conditions behind these exponential buildups shows that this phenomenon is universally present for physically reasonable accreting conditions. This noneternal mass inflation does not require the introduction of global spacetime concepts. We also show that various known results in the literature are recovered in the limit in which the inner trapping horizon asymptotically approaches a Cauchy horizon. Our results imply that black hole geometries with nonextremal inner horizons, including the Kerr geometry in general relativity, and nonextremal regular black holes in theories beyond general relativity, can describe dynamical transients but not the long-lived end point of gravitational collapse.

Non-Spherical Cavitation Bubbles: A Review

Cavitation is a phase-change phenomenon from the liquid to the gas phase due to an increased flow velocity. As it causes severe erosion and noise, it is harmful to hydraulic machinery such as pumps, valves, and screw propellers. However, it can be utilized for water treatment, in chemical reactors, and as a mechanical surface treatment, as radicals and impacts at the point of cavitation bubble collapse can be utilized. Mechanical surface treatment using cavitation impacts is called “cavitation peening”. Cavitation peening causes less pollution because it uses water to treat the mechanical surface. In addition, cavitation peening improves on traditional methods in terms of fatigue strength and the working life of parts in the automobile, aerospace, and medical fields. As cavitation bubbles are utilized in cavitation peening, the study of cavitation bubbles has significant value in improving this new technique. To achieve this, many numerical analyses combined with field experiments have been carried out to measure the stress caused by bubble collapse and rebound, especially when collapse occurs near a solid boundary. Understanding the mechanics of bubble collapse can help to avoid unnecessary surface damage, enabling more accurate surface preparation, and improving the stability of cavitation peening. The present study introduces three cavitation bubble types: single, cloud, and vortex cavitation bubbles. In addition, the critical parameters, governing equations, and high-speed camera images of these three cavitation bubble types are introduced to support a broader understanding of the collapse mechanism and characteristics of cavitation bubbles. Then, the results of the numerical and experimental analyses of non-spherical cavitation bubbles are summarized.

Why does the Milky Way have a metallicity floor?

ABSTRACT The prevalence of light element enhancement in the most metal-poor stars is potentially an indication that the Milky Way has a metallicity floor for star formation around $\sim 10^{-3.5}$ Z$_{\odot }$. We propose that this metallicity floor has its origins in metal-enriched star formation in the minihaloes present during the Galaxy’s initial formation. To arrive at this conclusion, we analyse a cosmological radiation hydrodynamics simulation that follows the concurrent evolution of multiple Population III star-forming minihaloes. The main driver for the central gas within minihaloes is the steady increase in hydrostatic pressure as the haloes grow. We incorporate this insight into a hybrid one-zone model that switches between pressure-confined and modified free-fall modes to evolve the gas density with time according to the ratio of the free-fall and sound-crossing time-scales. This model is able to accurately reproduce the density and chemo-thermal evolution of the gas in each of the simulated minihaloes up to the point of runaway collapse. We then use this model to investigate how the gas responds to the absence of H$_{2}$. Without metals, the central gas becomes increasingly stable against collapse as it grows to the atomic cooling limit. When metals are present in the halo at a level of $\sim 10^{-3.7}$ Z$_{\odot }$, however, the gas is able to achieve gravitational instability while still in the minihalo regime. Thus, we conclude that the Galaxy’s metallicity floor is set by the balance within minihaloes of gas-phase metal cooling and the radiation background associated with its early formation environment.

St. Petersburg through Venetian Eyes: An Episode in Late Eighteenth-Century Book Illustration

This article analyzes a print that was published in Venice in 1797 as the opening image to a biography of Catherine II. Certainly prepared during the empress’s life, the publication appeared just months after her death in a watershed year for Europe which saw the fall of the Republic of Venice. The print imagines the moment that Peter the Great founded the new city of St. Petersburg over ninety years earlier. Through an exploration of the carefully constructed messages in the print, this paper examines the legacy of the image of Peter in Western Europe against which Catherine was understood. It considers the imagery of St. Petersburg in relation to Venice: the capitals of two empires, one in its ascendency and one at the point of collapse.

Analytical solution and spectral structure of the two-photon anisotropic Rabi-Stark model

Since the realization of the strong coupling between light and matter in experimental setups, the quantum Rabi model and its generalized models describing the interaction between the boson field and the two-level system have attracted extensive interest again. The study of anisotropic generalized Rabi models enables us to better understand the novel physical properties of the interaction between light and matter in the ultra-strong and deep-strong coupling regions. In this work, the two-photon anisotropic Rabi-Stark model (tpARSM) is analytically solved by using the Bogoliubov operator approach and the su(1, 1) Lie algebra. We derive the G-function, whose zeros give the regular spectrum of the system. By studying the pole structure of the G-function and the coefficients in the function, exceptional solutions, including the first-order quantum phase transition points, doubly degenerate exceptional solutions and nondegenerate exceptional solutions, are obtained. By discussing the spectral structure, we give the conditions for the first-order quantum phase transition of tpARSM. Furthermore, we find that the property that all of the lowest doubly degenerate crossing points in the two-photon Rabi-Stark model have the same energy only holds for the special case of the tpARSM in which the anisotropy parameter is equal to 1. Finally, from the perspective of first-order quantum phase transitions, concise conditions for the ground state energy level to collapse to or escape from the collapse point for the tpARSM are presented. A good understanding of the tpARSM will lay a good foundation for studying the extended two-photon systems involving multiple levels and multiple bosonic modes, and even the relevant open quantum systems.

Enhancing the robustness of interdependent networks by positively correlating a portion of nodes

Cascading failures caused by interdependencies make modern coupled systems extremely fragile to failures. In existing network robustness enhancing methods, maximizing interlayer degree-degree correlations has been proven to be an effective way to improve the robustness of interdependent networks under random failures. Here, we propose a portion of nodes positively correlated strategy (PNC) to improve network robustness by positively correlating a portion of nodes, in which the nodes that are positively correlated are selected in descending order of degree, starting at a cutoff value. Based on percolation theory, we verify the effectiveness of PNC on different networks. And find that, when the nodes with the highest degree are preferentially correlated, i.e. the cutoff value takes the maximum degree, this strategy achieves a state-of-the-art optimization effect. In particular, for interdependent scale-free networks with power-law exponent γ that satisfies 2<γ<3 , we theoretically demonstrate that the highest degree preferentially correlated mode can maximize network robustness by changing the coupling state of the near 0 proportion of nodes. For γ = 3, such a mode can make the network turn into a second-order phase transition at the collapse point. Finally, we discuss the relationship between the robustness of optimized networks and common links in real-world networks.

Analysis of subsidence zone of the village access road in Jatirunggo, Semarang Regency using microtremor data

The rehabilitation of the subsidence phenomenon in Jatikurung sub-village, Jatirunggo village, Pringapus Subdistrict, Semarang Regency, Central Java, has been carried out for a long time however, it has never been successful. Every time an embankment is made, it is only a matter of time before another subsidence occurs. This research aims to investigate the subsurface structure of the subsidence sites. It is proposed to be used as a reference for structural planning in the treatment of road subsidence. Subsurface information is very useful in addressing the subsidence problem more effectively and precisely. The method used was by recording microtremor data and analyzing shear wave velocity and Poisson ratio as parameters to determine the type of subsurface layer. The obtained results are in the form of clay layers to bedrock layers at a depth of 35m. The movement occurred because of the soft or loose soil below and at the edge of the road above the impermeable clay layer. In addition, to the north side of the collapse point is a fairly deep cliff, which is a burden on the bedrock. When it was raining, the soil filled with water and there was even a flow of water in the soil deposits (piping) resulting in the ground movement toward the lower part.

Unilateral laser ventriculocordectomy results in increased arytenoid stability in horses with severe left sided recurrent laryngeal neuropathy.

There is no objective information reporting the effect of unilateral laser ventriculocordectomy (VeC) on arytenoid abduction or stability. To evaluate arytenoid stability and abduction in horses with severe recurrent laryngeal neuropathy (RLN) before and after unilateral laser VeC. Prospective cohort. Eight horses with grade C or D exercising laryngeal function that underwent unilateral laser VeC were included. Exercising endoscopy was performed before and ≥6 weeks after left-sided laser VeC. Arytenoid stability at maximal exercise was calculated by measuring the left-to-right quotient angle ratio (LRQ) of the corniculate processes at the points of maximal arytenoid abduction (expiration) and maximal arytenoid collapse (inspiration). For each horse, means of measurements obtained for four breaths pre- and post-operatively were used for statistical analysis. The difference in LRQ between inspiration and expiration was lower post-operatively (median 0.039; interquartile range [IQR] 0.032-0.047) compared with pre-operatively (median 0.158; IQR 0.083-0.249; p = 0.01) confirming the left arytenoid was more stable following unilateral laser VeC. The degree of improvement was significantly greater for grade D horses compared with grade C horses (p = 0.04). The LRQ measured on maximal abduction was also lower post-operatively (median 0.467; IQR 0.444-0.506) compared with pre-operatively (median 0.578; IQR 0.554-0.655; p = 0.02) indicating the left arytenoid was less abducted following surgery. The sample size was small, no racehorses were included and post-operative assessment was conducted at a variable time after surgery. Unilateral laser VeC in grade C and D RLN-affected horses results in slightly reduced left arytenoid abduction but increased arytenoid stability.

Eco-friendly aqueous binder derived from waste ramie for high-performance Li-S battery

Even the sulfur cathode in lithium-sulfur (Li-S) battery has the advantages of high theoretical energy density, wide source of raw materials, no pollution to the environment, and so on. It still suffers the sore points of easy electrode collapse due to large volume expansion during charge and discharge and low active materials utilization caused by the severe shuttle effect of lithium polysulfides (LiPSs). Therefore, in this work, ramie gum (RG) was extracted from ramie fiber degumming liquid and used as the functional binder to address the above problems and improve the Li-S battery's performance for the first time. Surprisingly, the sulfur cathode using RG binder illustrates a high initial capacity of 1152.2 mAh/g, and a reversible capacity of 644.6 mAh/g after 500 cycles at 0.5 C, far better than the sulfur cathode using polyvinylidene fluoride (PVDF) and sodium carboxymethyl cellulose (CMC) binder. More importantly, even if the active materials loading increased to as high as 4.30 mg/cm2, the area capacity is still around 3.1 mAh/cm2 after 200 cycles. Such excellent performances could be attributed to the abundant oxygen- and nitrogen-containing functional groups of RG that can effectively inhibit the shuttle effect of LiPSs, as well as the excellent viscosity and mechanical properties that can maintain electrode integrity during long-term charging/discharging. This work verifies the feasibility of RG as an eco-friendly and high-performance Li-S battery binder and provides a new idea for the utilization of agricultural biomass resources.

ТЕОРЕТИЧЕСКОЕ ОБОСНОВАНИЕ ТРАНСПОРТЕРА ДЛЯ ВЫГРУЗКИ КОРНЕПЛОДОВ ОВОЩНЫХ КУЛЬТУР И КЛУБНЕЙ КАРТОФЕЛЯ ИЗ ХРАНИЛИЩА

The need to develop specialized machines and equipment for laboratory and field research on potato breeding is due to the fact that the methodology of breeding processes and the first stages of seed production involves comparing many plants of different origins and selecting the best for further work up to the creation of a new variety or transfer of seeds for propagation in production conditions. The large variability of machines for unloading vegetables and potatoes does not adequately prevent damage to vegetable and potato products, which is due to the imperfect design of such machines, including the imperfection or absence of patterns of automated control of the technological process of work and justification of the parameters of their working parts. The purpose of the study is to substantiate the parameters of the conveyor for unloading vegetable crops and potatoes into storage and to determine the patterns of formation of the control signal of the transfer function of automatic control of operation. The power required to move the pick-up depends on the maximum pressure force of introducing the intake element into the embankment, the mass of the pick-up and the rolling resistance coefficients of the running wheels of the pick-up and transport sections. The length of the unloading conveyor of the machine is determined by the reserve zone to prevent wheels from hitting the tubers, their maximum difference in the embankment, the height of the layer, as well as the angle of inclination of the unloading conveyor. The width of the conveyor belt for unloading products from storage is determined by the values of the coefficient of friction of root crops on the surface of the belt, the coefficient of working time utilization and the forward speed of the conveyor belt. After removing the collapsed mass of tubers, the line of crumbling slopes and the limiting equilibrium are a straight line, characterized by an empirical equation for determining the coordinates of the tuber collapse point, the height of the tuber layer and the embankment collapse coefficient. When the feeder tubers are introduced into the surface of the embankment, the formation of slopes occurs in four stages: the formation of a natural slope, a limiting equilibrium slope, a shedding slope and a product collapse slope.

Predicting the collapse process and tipping points for mutualistic and competitive networks with k-core method

Abstract Ecosystems generally have the self-adapting ability to resist various external pressures or disturbances, which is always called resilience. However, once the external disturbances exceed the tipping points of the system resilience, the consequences would be catastrophic, and eventually lead the ecosystem to complete collapse. We capture the collapse process of ecosystems represented by plant-pollinator networks with the k-core nested structural method, and find that a sufficiently weak interaction strength or a sufficiently large competition weight can cause the structure of the ecosystem to collapse from its smallest k-core towards its largest k-core. Then we give the tipping points of structure and dynamic collapse of the entire system from the one-dimensional dynamic function of the ecosystem. Our work provides an intuitive and precise description of the dynamic process of ecosystem collapse under multiple interactions, and provides theoretical insights for further avoiding the occurrence of ecosystem collapse.

Avalanche scaling law for heterogeneous interfacial fracture

A new approach is proposed to study the statistical law of avalanches due to the fracture of a heterogeneous interface. Firstly, a discrete interface is considered as a bundle of fibers clamped with two elastic circular plates, fiber strength being either a random variable or a stochastic field. Based on the theory of solid mechanics, equations governing the dynamic fracture process of fibers under tension are exactly derived and solved. The statistical law of fracture avalanches is accurately obtained. By tuning parameters, the model covers the whole scheme of stress-transfer mechanism due to fiber breaking from local load sharing to equal load sharing. Results show that the distribution of avalanche size of interfacial fracture follows a power-law relation, with the power exponent in the range [1.5,2.5], depending on both disorders of interface and stiffness of plates. Particularly, the exponent monotonically increases with plate stiffness to the value 2.5, a universal constant obtained by Hemmer and Hansen (1992). Then, the fracture of a laminated interface is analyzed. By discretizing the interface to a set of prismatic elements, the problem reduces to that of a discrete interface. Similar statistical behaviors are also observed. Furthermore, the temporal variation of avalanche scaling law is investigated. It is shown that in the vicinity of collapse point, the exponent of each time window is smaller than the exponent evaluated with the whole time series of event, probably a precursor for imminent catastrophic failure of interface.

Improving voltage collapse point under transmission line outage by optimal placement and sizing of SVC using genetic algorithm

In many power systems, voltage instability can increase the risk of voltage collapse and, as a result, turn the power system toward a blackout. Therefore, increasing the voltage collapse point is required. A transmission line outage is an emergency condition in power systems that can lead to voltage instability and voltage collapse. Thus, it is expected to employ shunt-connected flexible AC transmission systems (FACTS) such as the static var compensator (SVC) to increase the voltage collapse point when lines outage. This paper presents the genetic algorithm (GA) application to optimal placement and sizing of an SVC for increasing voltage collapse points following lines outage. The continuation power flow (CPF) technique has been used to determine the maximum loading point (MLP) corresponding to the point of voltage collapse. Also, to reduce the number of scenarios when line outages occur, a list in ascending order is established based on the line outage priority (LOP). The IEEE 14-bus test system is chosen to carry out simulations, and an SVC will be installed in the system based on the GA results. Simulation results confirm the effectiveness of an SVC for improving voltage stability as well as increasing voltage profile.

Piezofluorochromism in Hierarchical Porous π-stacked Supermolecular Spring Frameworks from Aromatic Chiral Cages.

Piezochromic materials that exhibit pressure-dependent luminescence variations are attracting interest with wide potential applications in mechanical sensors, anticounterfeiting and storage devices. Crystalline porous materials (CPMs) have been widely studied in piezochromism for highly tunable luminescence. Nevertheless, reversible and high-contrast emission response with a wide pressure range is still challenging. Herein, the first example of hierarchical porous cage-based πOF (Cage-πOF-1) with spring structure was synthesized by using aromatic chiral cages as building blocks. Its elastic properties evaluated based on the bulk modulus (9.5 GPa) is softer than most reported CPMs and the collapse point (20.0 GPa) significantly exceeds ever reported CPMs. As smart materials, Cage-πOF-1 displays linear pressure-dependent emission and achieves a high-contrast emission difference up to 154 nm. Pressure-responsive limit is up to 16 GPa, outperforming the CPMs reported so far. Dedicated experiments and density functional theory (DFT) calculations illustrate that π-π interactions-dominated controllable structural shrinkage and porous-spring-structure-mediated elasticity is responsible for the outstanding piezofluorochromism.

Piezofluorochromism in Hierarchical Porous π‐stacked Supermolecular Spring Frameworks from Aromatic Chiral Cages

AbstractPiezochromic materials that exhibit pressure‐dependent luminescence variations are attracting interest with wide potential applications in mechanical sensors, anticounterfeiting and storage devices. Crystalline porous materials (CPMs) have been widely studied in piezochromism for highly tunable luminescence. Nevertheless, reversible and high‐contrast emission response with a wide pressure range is still challenging. Herein, the first example of hierarchical porous cage‐based πOF (Cage‐πOF‐1) with spring structure was synthesized by using aromatic chiral cages as building blocks. Its elastic properties evaluated based on the bulk modulus (9.5 GPa) is softer than most reported CPMs and the collapse point (20.0 GPa) significantly exceeds ever reported CPMs. As smart materials, Cage‐πOF‐1 displays linear pressure‐dependent emission and achieves a high‐contrast emission difference up to 154 nm. Pressure‐responsive limit is up to 16 GPa, outperforming the CPMs reported so far. Dedicated experiments and density functional theory (DFT) calculations illustrate that π–π interactions‐dominated controllable structural shrinkage and porous‐spring‐structure‐mediated elasticity is responsible for the outstanding piezofluorochromism.

Limiting Overdistention or Collapse When Mechanically Ventilating Injured Lungs: A Randomized Study in a Porcine Model.

Rationale: It is unknown whether preventing overdistention or collapse is more important when titrating positive end-expiratory pressure (PEEP) in acute respiratory distress syndrome (ARDS). Objectives: To compare PEEP targeting minimal overdistention or minimal collapse or using a compromise between collapse and overdistention in a randomized trial and to assess the impact on respiratory mechanics, gas exchange, inflammation, and hemodynamics. Methods: In a porcine model of ARDS, lung collapse and overdistention were estimated using electrical impedance tomography during a decremental PEEP titration. Pigs were randomized to three groups and ventilated for 12 hours: PEEP set at ⩽3% of overdistention (low overdistention), ⩽3% of collapse (low collapse), and the crossing point of collapse and overdistention. Measurements and Main Results: Thirty-six pigs (12 per group) were included. Median (interquartile range) values of PEEP were 7 (6-8), 11 (10-11), and 15 (12-16) cm H2O in the three groups (P < 0.001). With low overdistension, 6 (50%) pigs died, whereas survival was 100% in both other groups. Cause of death was hemodynamic in nature, with high transpulmonary vascular gradient and high epinephrine requirements. Compared with the other groups, pigs surviving with low overdistension had worse respiratory mechanics and gas exchange during the entire protocol. Minimal differences existed between crossing-point and low-collapse animals in physiological parameters, but postmortem alveolar density was more homogeneous in the crossing-point group. Inflammatory markers were not significantly different. Conclusions: PEEP to minimize overdistention resulted in high mortality in an animal model of ARDS. Minimizing collapse or choosing a compromise between collapse and overdistention may result in less lung injury, with potential benefits of the compromise approach.

The poverty of embodiment in the work of Juhani Pallasmaa

In books such as The Eyes of the Skin, architectural theorist Juhani Pallasmaa posits unmediated sensual encounters as the site of authentic engagement with the built environment. Such ideas are prevalent in mainstream architectural discourse today. In this article, I show that they are also highly problematic. Pallasmaa rejects visual intentionality, construing it as the instrument of an objectifying reason that distances us from our ‘being-in-the-world’. Referring to the phenomenologist philosophies of Martin Heidegger and Maurice Merleau-Ponty, and indebted to Henri Bergson’s concept of duration through lived experience, Pallasmaa’s theory promises a poetic inhabitation of the world, irreducible to reason and characterised by an animistic embodiment, allegedly offering a more meaningful architectural experience. Informed by contemporary rationalist thought and drawing on neuroscientific, anthropological and philosophical arguments, I first argue that Pallasmaa’s project is weakened to the point of collapse by the misunderstanding of his intellectual resources, particularly with respect to the use of incompatible concepts of embodiment in Heidegger’s and Merleau-Ponty’s works. I then show how his ideas of embodiment, disinterested vision and sensuality constitute an impoverished account of lived experience that, far from overcoming alienation, mystifies it. I specifically discuss Pallasmaa’s analysis of Frank Lloyd Wright’s Taliesin West, his comparisons of human- and animal-created structures and his forays into neuroscience. Finally, I dispute Pallasmaa’s claim that an immediate sensual encounter is the route to authentic engagement with the world, and question whether the unmediated lived experience he yearns for is even possible.

Changes in vulnerability of global container shipping networks before and after the COVID-19 pandemic

To explore the changes in vulnerability of global container shipping networks before and after the COVID-19 pandemic, this study presents a novel method for identifying the critical collapse point of the global container shipping network based on geospatial connectivity changes and network collapse process under the deliberate attack. Additionally, we propose a quantitative approach to assess the trends and degree of changes in network vulnerability. To accomplish this, we construct the global container shipping network for 2015, 2017, 2019, and 2021, utilizing port and route statistics of the top 100 global container liner companies for analysis. The outcomes indicate that the global container shipping network's tolerance to deliberate attacks was 7.98%, 8.52%, 9.57%, and 9.72% in 2015, 2017, 2019, and 2021, respectively, implying that the global container shipping network continued its trend of gradual strengthening before the COVID-19 pandemic, but with a relatively low change in tolerance of 1.57%. The factors influencing the changing vulnerability of the global container shipping network before and after the COVID-19 pandemic include declining port efficiency, shorter and more trans-regional routes, and retaliatory increases in global container shipping trade. Ultimately, we provide relevant policy recommendations to continuously secure the global container shipping network's interconnectivity.

Large-scale molecular dynamics simulations of bubble collapse in water: Effects of system size, water model, and nitrogen

Molecular dynamics simulations in the microcanonical ensemble are performed to study the collapse of a bubble in liquid water using the single-site mW and the four-site TIP4P/2005 water models. To study system size effects, simulations for pure water systems are performed using periodically replicated simulation boxes with linear dimensions, L, ranging from 32 to 512 nm with the largest systems containing 8.7 × 106 and 4.5 × 109 molecules for the TIP4P/2005 and mW water models, respectively. The computationally more efficient mW water model allows us to reach converging behavior when the bubble dynamics results are plotted in reduced units, and the limiting behavior can be obtained through linear extrapolation in L−1. Qualitative differences are observed between simulations with the mW and TIP4P/2005 water models, but they can be explained by the models’ differences in predicted viscosity and surface tension. Although bubble collapse occurs on time scales of only hundreds of picoseconds, the system sizes used here are sufficiently large to obtain bubble dynamics consistent with the Rayleigh–Plesset equation when using the models’ thermophysical properties as input. For the conditions explored here, extreme heating of the interfacial water molecules near the time of collapse is observed for the larger mW water systems (but the model underpredicts the viscosity), whereas heating is less pronounced for the TIP4P/2005 water systems because its larger viscosity contribution slows the collapse dynamics. The presence of nitrogen within the bubble only starts to affect bubble dynamics near the very end of the initial collapse, leading to an incomplete collapse and strong rebound for the mW water model. Although nitrogen is non-condensable at 300 K, it becomes highly compressed and reaches a liquid-like density near the collapse point. We find that the dissolution of nitrogen is much slower than the movement of the collapsing water front, and the re-expansion of the dense nitrogen droplet gives rise to bubble rebound. The incompatibility of the collapse and dissolution time scales should be considered for continuum-scale modeling of bubble dynamics. We also confirm that the diffusion coefficient for dissolved nitrogen is insensitive to pressure as the liquid transitions from a compressed to a stretched state.

Strengthening of RC beams with inadequate lap splice length using cast-in-situ and anchored precast ECC ferrocement layers mitigating construction failure risk

Design standards necessitate the use of a sufficient lap splice length when dealing with longer spans of Reinforced Concrete (RC) members. An inadequate lap splice length results in a reduction of both the flexural strength and ductility of reinforced concrete beams. The failure risk of these beams is considered a potential threat which is experimentally identified, numerically analyzed, and carefully mitigated in this research to increase building safety and sustainability to avoid risk of construction failure. The ongoing experimental and numerical research focuses on examining the structural performance of RC beams with insufficient lap splice length, which have been fortified through various applications of Engineered Cementitious Composite (ECC) ferrocement layers. A total of eleven beams, divided into four groups, were purposefully designed and tested under bending loads until they reached the point of collapse. The investigated parameters included the casting technique, installation strategy, and anchorage length (La) for such layers. Cast in situation and pre-casting scenarios were utilized in order to cast the strengthening ECC layers. The La for all layers was designed to be the main studied variable beside type of casting and installation technique. Three La values were studied: 30D, 40D, and 50D where D is the bar diameter of main reinforcement steel in tension side. It was found that, the application of chemical anchor bolts in cast in situation ECC ferrocement layers credited the higher enhancement in both cracking and ultimate stages by about 92–137% and 114–164% for cracking and ultimate levels, respectively. Then, the experimentally measured outcomes were employed for developing nonlinear Finite Element Models (FEMs) to simulate the performance of such ECC ferrocement layers that employed. The variance between numerical results and experimental counterparts ranged in between 6% and 9%, achieving an acceptable variance.