Repeated Load Research Articles

Punching Shear Capacity of RC Flat Slabs with Steel and Superelastic Ni-Ti Shape Memory Shear Reinforcement under Repeated Loads

Flat slab systems are a popular choice among engineers because of their numerous advantages, such as reduced building height, flexibility in spatial layout by eliminating the need for beams, and cost savings. However, Brittle slab failure under punching shear presents a considerable challenge. The primary objective of this study was to examine how flat slabs respond to PS and conduct an experiment using steel and superelastic Ni-Ti shape memory alloy (SMA) bars as shear reinforcement to assess their effectiveness in improving the PS capacity of flat slab-column connections under vertical Repeated load. Nine half-scale samples were tested, consisting of 1100 × 1100 × 120 mm slabs with a protruding column from one side of 150 × 150 mm and 400 mm height. The factors considered in this research were the type of materials, spacing between stirrups, stabilization method, and inner RFT. After that, finite element analysis by using ABAQUS 6.14 was developed to simulate all the tested specimens. The finite element analysis showed identical results compared to the experimental ones concerning energy absorption, load capacity, absorbed energy, and model stiffness. According to the experimental and finite element analysis findings, the flat slab reinforced with inclined stirrups exhibited a significant increase in punching strength, ranging from 28.8% to 51.3% compared with the control specimen. The stiffness increases by 8.5% when the distance between stirrups is reduced to 0.5d, and inclined-shaped memory alloy stirrups are employed.

Stiffness evaluation of coarse unbound granular materials using large-scale repeated load triaxial test

This research investigates the effect of downscaling coarse unbound granular material (UGM) for characterization of the resilient modulus with large-scale repeated load triaxial testing. Four open-graded and two dense-graded materials are downscaled based on the particle size distribution curve and upper sieve size for subbase materials of crushed rock (CR) 22/125 mm and CR 0/125 mm as defined by the Norwegian road design regulation.The results were evaluated using the K-θ model and Uzan’s model. The findings for CR 4/22 mm, CR 6/32 mm, CR 8/45 mm, and CR 11/63 mm indicate that downscaling of coarse open-graded UGMs could be applicable for characterization of the resilient modulus. The results for dense-graded UGMs CR 0/22 mm and CR 0/63 mm indicate that downscaling reduces the resilient modulus. Further research should include complementary gradings and rock types.

Characterising the permanent deformation of subgrade soils under seasonal variation

Rutting, a prevalent failure mode in flexible pavements, largely stems from subgrade issues. Despite this, there is a lack of standard protocols to evaluate subgrade rutting or permanent deformation (PD). This study attempted to characterise PD in subgrades, focusing on a poorly graded sand and two silty sands. Moisture contents above and below optimum levels were considered to account for seasonal variations. The research involved adapting a test to assess the PD by determining typical stresses on the subgrade. Moreover, given these soils' unsaturated state and medium- to fine-grained nature, suction is an important factor. Suction-controlled multi-stage Repeated Load Triaxial tests were conducted, and the results were fitted by a PD model modified to account for suction. The characterisation was compared with the subgrade strain criterion used in pavement design solutions. Results indicated discrepancies between the PD characterisation and strain criteria predictions, with the silty sands performing better than the poorly graded sand, consistent with the shakedown theory.

Subsurface hardening of Al irradiated with ultrafast infrared laser

The effect of femtosecond laser shock peening on a model Al-0.3Mn alloy was investigated experimentally and numerically by molecular dynamics. Micro-diffraction experiments performed at synchrotron source revealed the depth profiles of the residual stress and the stored energy of dislocations, a measure of local plasticity. The depth of the maximum compressive stress did not coincide with that of the maximum dislocation energy, which was found at the surface. The interaction between the laser and the metal was simulated with LAMMPS using a two-temperature molecular dynamics package. The model accurately described the equation of state of aluminum and showed nearly equal resolved shear stresses on all slip systems at the wavefront. The dislocation density at a depth of 1 μm, predicted by the Meyers' model [1], was higher than the experimental data, suggesting possible recovery due to the increased temperature of the sample after repeated shock loading.

Productive chemistry induced by mechanochemically generated macroradicals.

Large or repeated mechanical loads degrade polymeric materials by accelerating chain fragmentation. This mechanochemical backbone fracture usually occurs by homolysis of otherwise inert C-C, C-O and C-S bonds, generating highly reactive macroradicals. Because backbone fracture is detrimental on its own and the resulting macroradicals can initiate damaging reaction cascades, a major thrust in contemporary polymer mechanochemistry is to suppress it, usually by mechanochemical release of "hidden length" that dissipates local molecular strain. Here we summarize an emerging complementary strategy of channelling mechanochemically generated macroradicals in reaction cascades to form new load-bearing chemical bonds, which enables local self-healing or self-strengthening, and/or to generate mechanofluorescence, which could yield detailed quantitative molecular understanding of how material-failure-inducing macroscopic mechanical loads distribute across the network. We aim to identify generalizable lessons derivable from the reported implementations of this strategy and outline the key challenges in adapting it to diverse polymeric materials and loading scenarios.

Experimental and numerical based model formulation for estimation of subgrade resilient modulus using the repeated load CBR test considering in situ state of stress

Characterizing subgrade in terms of resilient modulus is a crucial aspect of flexible pavement design. This paper proposes a methodology and predictive model to estimate the resilient modulus with better consideration of subgrade soils’ in situ stress state using a simple Repeated Load CBR (RLCBR) test. RLCBR tests were conducted on eight subgrade soils at three moisture contents. Numerical studies were conducted by simulating the CBR test in the commercial package LS-DYNA® to understand the stress state under plunger loading concerning field conditions. A new model was proposed for the characterization of subgrade soils based on laboratory RLCBR tests and the FEM, considering the stress state experienced by subgrade soils in the field. The proposed model was validated using data from four other soils and showed good agreement. The study model showed a better predictive capacity for the low plastic subgrade soils than previously developed models. Practicing engineers can use the developed model for estimating the subgrade resilient modulus at the recommended stress state for mechanistic pavement design while understanding the soil’s load-deformation behavior.

Design of a continuously repeated impact method with constant amplitude based on Hopkinson bar: Principle and impact fatigue life testing

The lack of reliable testing methods and standards hinders systematic research on the impact fatigue performance of materials. The aim of developing an impact fatigue test method is to generate repeated impact loads with a constant amplitude, which is difficult to achieve using various existing impact test devices. This study investigated the principles of cyclic loading-resetting and constant-amplitude loading based on the split Hopkinson pressure bar (SHPB) system, established a novel impact fatigue test device, and verified the developed method by testing the impact fatigue life of a Ti-6Al-4V alloy. Electromagnetic valves, laser sensors, and a vacuum pump were used in the developed device to launch and reset the striker bar; a servo motor and laser sensors were used to reset the loading bars and specimen, and the entire system was controlled by a programmable controller to achieve continuously repeated loading. To achieve constant-amplitude loading, the conditions required to ensure that the specimen moves away from the incident bar before the returning stress wave reloads the specimen was derived. It was found that a constant-amplitude repeated impact on the specimen could only be achieved through the precise design of the geometric configuration and material of the loading bars. This method is considerably simpler than various existing methods based on energy absorption and is more applicable to impact fatigue tests. The verification tests showed that the highest loading frequency of the device was 0.5 Hz, the loading rate exceeded 105 kN/s, and the amplitude error of the repeated impact loads did not exceed 2.45 %. Under loads with the same amplitude, the impact fatigue life of a Ti-6Al-4V alloy was considerably shorter than the non-impact (low strain rate) fatigue life, which indicates the necessity of investigating the strain rate effect on the fatigue performance of materials.

Investigation on Dynamic Stability of Cement-Stabilized Expansive Soil Subgrades Subjected to Repeated Heavy-Haul Train Loads

The dynamic characteristics of the filler are intricately linked to the stability of the subgrade. In this investigation, relying on Haoji (Haolebaoji-Ji’an, China) heavy-haul railway engineering, cyclic triaxial tests were executed to scrutinize the dynamic attributes exhibited by the 3%–5% cement-stabilized expansive soil (CSES) across a series of diverse cyclic stress, confining pressures, and frequencies. Concurrently, in situ vibration trials were undertaken to dissect the dynamic characteristics inherent to the CSES subgrade. The outcomes of cyclic triaxial tests indicate that the augmentation in both the dynamic shear strength and modulus of CSES by a factor of 2–3, coupled with an escalation of the critical dynamic stress threshold by five tosix times, is attributed to the heightened internal structural density within the CSES compared to virgin expansive soil. In identical settings, it is noteworthy that the mean critical dynamic stress threshold observed for CSES surpasses that of Group A filling by a factor of 1.5–1.7. Furthermore, the maximum critical dynamic stress exhibited by CSES achieves a 1.2-fold superiority over its lime-stabilized expansive soil (LSES). The outcomes gleaned from the in situ vibration tests elucidate that, when subjected to the passage of a high-velocity train traveling at 120 km/hr, bearing the load of 25–30 tons per axle, the subgrade surface exhibits dynamic stress ranging from 98.57 to 116.07 kPa. Meanwhile, the dynamic stress undergoes a notable escalation due to rainfall infiltration, intensifying by a factor of 1.02–1.28 times its original magnitude. The influence depth of dynamic stress extends 1.4–1.6 times beyond the designed subgrade bed thickness of 2.5 m. Notably, the critical dynamic stress of the filler surpasses the dynamic stress at the same position, underscoreing the capacity of 3%–5% CSES filling for heavy-haul railways to ensure long-term dynamic stability.

Numerical investigation on the effect of repeated surface surcharge loading on soil deformation and tunnel displacement in structured soft clay

Shanghai soft clay is a typical marine clay with specific structural characteristics. The tunnel and overlying soft clay may undergo repeated surface surcharge loading, such as the temporary soil stacking. Assessing the extent of structured soft clay deformation and tunnel displacement caused by repeated surface surcharge loading is of great significance for evaluating of the safety of ground structures and underground tunnels. In this study, the effects of repeated surface surcharge loading on the soil and tunnel displacement were numerically investigated. The finite element code DBLEAVES with an elasto-plastic constitutive model (Shanghai model) that describes the mechanical properties and structural characteristics of natural clay was used to simulate the soil response. The parameters of the constitutive model were obtained through geotechnical testing. The effects of the soil structural characteristics, seepage conditions, and loading conditions on the soil response and tunnel displacement were analyzed. The numerical results show that the maximum excess pore pressure of clay decreased as the number of loading cycles increased. The effects of the structural characteristics cause greater displacement, whereas the effects of the degradation parameters of the structure are more significant than the initial degree of the structure. The differences in the vertical displacement of the tunnel and overlying soils owing to the structural characteristics become apparent with an increase in surface surcharge loading. However, the effects of structural characteristics become less significant as the depth increases. The seepage conditions and loading method primarily affect the build-up of excess pore pressure and the development of effective stress paths. For soils inside the surcharge area, a flexible surcharge produces a greater vertical displacement than a rigid surcharge. As the burial depth increased, the effects of the seepage conditions and loading method showed a declining tendency.

New insights into the load sequence effect: Experimental characterization and incremental modeling of plain high-strength concrete under mode II fatigue loading with variable amplitude

Reinforced concrete (RC) infrastructure typically endures repeated subcritical loading throughout its operational lifespan, potentially compromising structural integrity. A realistic loading condition of these structures consists of constantly changing maximum and minimum load events. Characterizing the fatigue response of concrete proves challenging due to its heterogeneous and quasi-brittle nature, leading to varying fatigue lifetimes depending on the loading sequence. Understanding the impact of this so-called load sequence effect stands as a critical facet in ensuring structural longevity and reliability of current infrastructure. This paper offers insights into this phenomenon, focusing on unraveling the intricate behavior of plain concrete under multistage fatigue loading. Since the experimental investigation of the load sequence effect is highly complex due to the large scatter of test results, a newly developed, mode II test setup was employed. The advantage of this test setup resides in the precise specification of stress state and fracture zone. The systematic investigation of over 50 specimens elucidates the pronounced load sequence effect and provides insight into the underlying mechanisms. Based on these experimental results, a deformation-based incremental modeling approach was developed which considers the effect of loading sequence and provides not only the fatigue life but also the entire evolution of deformation. The experimental recalculation underscores the efficacy of this approach over the conventional Palmgren–Miner (P–M) rule.

Design and Performance Study of a Six-Leg Lattice Tower for Wind Turbines

A new type of spherical node was used to design a laboratory-scale prototype of a six-leg lattice of steel tubes and concrete for application as a wind turbine tower. Repeated load tests were performed on the prototype tower for several weeks to evaluate its load-carrying capacity, deformation, energy consumption, stress distribution based on damage patterns, hysteresis curves, skeleton curves, strength, and stiffness degradation curves. The findings indicated that the prototype tower underwent thread damage to the high-strength bolts of the inclined web and weld damage between the inclined web and sealing plate. Although the stress differences between different measurement points were significant, the stress values were small at most of the measurement points. The maximum equivalent stress value was 294 MPa, which appeared in the middle layer of the BC surface. The P-Δ hysteresis curve had an inverse “S”-shape, and the bearing capacity was high. The maximum energy dissipation appeared in the 1.75 Δy loading stage. The peak load of the specimen can reach 376.2 kN, and the corresponding peak displacement is 37 mm. However, the average ductility coefficient was only 2.33, indicating little plastic deformation. The maximum strain of the tower column foot is 1800 με, and the force of the inclined web member in the middle layer is the largest. The strain of the transverse web bar increased significantly after the tower yielded, which contributed to maintaining the integrity of the structure.

Evaluating the Fatigue-Cracking Resistance of North Dakota’s Asphalt Mixtures

Fatigue cracking is a critical pavement distress caused by extreme environmental conditions and heavy repeated cyclic loading. Performance-based design methods that use mechanistic models focus on material performance properties, creating an opportunity to use engineered and recycled materials such as reclaimed asphalt pavement (RAP). The primary goal of this study was to use the simplified viscoelastic continuum damage (S-VECD) model to assess the fatigue behavior of North Dakota’s asphalt mixtures. Eight mixtures typically used in North Dakota were sampled and underwent | E*| testing to determine their linear viscoelastic (LVE) properties. The S-VECD tests were conducted on the same mixtures to determine their damage characteristics. The outputs from the two tests were exported to the FlexMATTM software to obtain their damage characteristic curves, DR failure criterion parameters, and Sapp-index values. CT-index values for the same mixtures were obtained from the North Dakota Department of Transportation (NDDOT). The results revealed that the mixture used for HWY 52, which does not contain RAP, was least susceptible to fatigue cracking. The mixture used for HWY 6, which contains the highest RAP content (25%), had the lowest fatigue resistance, revealing RAP’s stiffening effect on asphalt mixtures. The mixture used for HWY 1, which used the performance grade (PG) 58S-34 binder, had the second-highest fatigue-cracking resistance despite containing 15% RAP, indicating that binder grade affects an asphalt mixture’s fatigue behavior. A relatively low correlation was observed between the CT-index and Sapp-index.

The Effect of Nano-Hydrated Lime on the Durability of Hot Mix Asphalt

Recently, some of Iraq's newly constructed asphalt concrete pavements showed premature failures with significant negative impacts on roadway safety and the economy. Using Nano hydrated lime (NHL) in pavement construction could be one of the possible steps to improve pavement durability. This article discusses how NHL affects the durability of hot mix asphalt. NHL was added in two methods to the asphalt concrete mixture for the wearing course. The first is the dry method, i.e., on the aggregate, whereas the second is the wet addition method, i.e., to the bitumen. The percentages were tried for each additional method; 1, 2, and 3% by weight of aggregate for the dry method and 0.5, 1, and 1.5% by weight of asphalt concrete for the wet method. The optimum asphalt cement contents were evaluated using the Marshall procedure. Asphalt concrete mixes were prepared at their optimum asphalt content and then tested to evaluate their durability properties, including moisture damage and permanent deformation. These properties have been evaluated using indirect tensile strength and uniaxial repeated loading tests. The results show that the NHL has improved the permanent deformation characteristics and resistance to moisture susceptibility.

Experimental research into the dynamic damage characteristics and failure behavior of rock subjected to incremental repeated impact loads

The damage to rocks caused by frequent disturbance loads is a major issue in rock engineering. Understanding the failure behaviors and establishing the dynamic energy-damage model of rock under constant and incremental repeated impact loads are key to the structural safety and stability design of rock mass engineering works. In this work, the split Hopkinson pressure bar (SHPB) system and an ultrasonic measuring system were used to test constant and incremental repeated impact loads on red sandstone. The damage evolution of red sandstone was revealed under constant and incremental repeated impact loads, the energy-damage model of constant and incremental repeated impact loads was established, the crack expansion pattern and fatigue failure properties were studied, and the changing trend of the critical damage amount and the fractal characteristics of block after fatigue failure were investigated. The experimental results show that: the dynamic strength of red sandstone shows an overall decreasing trend with the impact velocity and the number of impacts under constant repeated impact loads. The damage evolution of the specimens follows an inverted S-shaped pattern of development. The critical damage amount is negatively correlated with the impact velocity. As the impact velocity is increased, the crack expansion velocity and main-body block size of the specimens after destruction increase. Under incremental repeated impact loads, the dynamic strength of red sandstone increases with the velocity incremental gradient and the number of impacts, and the damage to the specimens shows an accelerated upwardly concave trend. The critical damage amount and the incremental gradient demonstrate an alternating trend of negative-positive correlations. The crack expansion velocity is gradually accelerated, and the main-body block size of specimens after destruction displays a trend of growing and then reducing with the incremental gradient.

Comparative analysis of cold in-place recycling for roadway maintenance and rehabilitation from the perspectives of technical-cost-environmental nexus

Cold-in-place recycling (CIR) is a sustainable road pavement maintenance technology for its on-site operation and complete reuse of reclaimed asphalt pavement. However, its sustainable performance has not been thoroughly investigated. This study aims to systematically assess and compare CIR against three alternative maintenance technologies from technical, cost and environmental perspectives, specially taking into account different numbers of repaired layers. The technical improvement in full-depth loading resistance is evaluated using a newly developed multi-sequenced repeated load (MSRL) test. Environmental impacts are assessed through life cycle assessment (LCA), while cost analysis is conducted using life cycle cost analysis (LCCA), with consistent system boundary applied. Additionally, a nexus analysis is performed using a modified Boston Consulting Group (BCG) matrix to comprehensively examine the sustainable performance of different treatments and further explore the synergies and trade-offs among various assessment aspects. The multi-dimensional sustainable assessment results reveal the influence factors in each perspective. Final BCG matrix shows that CIR can achieve the comparable technical performance to the conventional maintenance treatment, while reducing GHG emissions by 60.8% and cost by 45.8%. The methodology and findings of this study are expected to provide helpful insights for decision-makers in reducing negative impacts and promoting integrated management for sustainability.

Bender element sensor technology to quantify local stiffness enhancement of geogrid-stabilized aggregate specimens

Geogrids improve pavement performance and extend lifespan by making the unbound aggregate base/subbase course stiffer. Extruded (i.e., punched and drawn) geogrids are widely used in pavement applications. This paper presents an experimental evaluation of multi-axial extruded geogrids with various aperture shapes for pavement applications. The study quantified modulus enhancement ratio and identified the extent of the geogrid-stiffened zone. Two types of aggregates (i.e., crushed limestone and partially crushed gravel), commonly used in Illinois for base or subbase course, were utilized. Repeated load triaxial tests were conducted on 6-in. diameter and 12-in. height cylindrical specimens instrumented with embedded shear wave transducers in the form of Bender Element (BE) sensors. The BE pairs were horizontally placed at three different heights above the geogrid. Resilient moduli of the aggregate samples were determined following the AASHTO T 307 standard test procedure. Concurrently, the localized small-strain moduli at different heights above the midheight of the specimen were determined from the shear wave velocities computed according to the first arrival times from the BE sensors recorded at the end of the application of each stress state. The results reveal that resilient modulus tests do not capture the geogrid effects, while BE sensors can quantify the local stiffness enhancement due to a geogrid, and the extent of the geogrid-stiffened zone. Results show that the multi-axial geogrids provided a 45% increase in small strain modulus for both aggregate types in the vicinity of the geogrid.

Repeated load triaxial tests of WickGrid™ stabilized base materials

In road construction, geogrids are frequently used to stabilize the base course through their lateral confinement applied to the base materials. Wicking fabrics are also used to improve road performance by installing them at the road base and subgrade interface to remove water from the road and reduce the build-up of pore water pressure while providing a separate function to mitigate the weak subgrade intrusion into the base course. However, the combined use of these two materials on the road has not been reported. This study aims to investigate the effectiveness of using an innovative geosynthetic composite called WickGrid™ in stabilizing the base materials. WickGrid™ is made by high stiffness biaxial polypropylene (PP) geogrid, heat bonded to a continuous filament nonwoven geotextile having wicking properties. To achieve the objectives, repeated load triaxial tests were conducted on sand materials to evaluate the improvement of the base materials in accordance with the AASHTO T 307-99(2021). The specimens were stabilized with WickGrid™ placed at the mid-height of the specimens. Meanwhile, unstabilized specimens and specimens stabilized with biaxial geogrids were also tested for comparison. The outcomes of these tests would allow for quantifying the beneficial effects of WickGrid™ on the improvement of road bases.

The response of glass fibre reinforced PEKK laminates subjected to single and multiple impact loading

This paper presents a study on the impact behaviour of newly-developed composites based on S-glass fibre reinforced PEKK (GF/PEKK) composites subjected to single and repeated impact loading. The laminates, with a thickness of 2 mm and fibre weigh fraction of 60 wt%, were manufactured by stacking eight plies of GF/PEKK woven prepregs using a hot compression moulding technique, and impacted centrally using a drop-weight apparatus. Beginning with a single impact test, these samples were subjected to repeated impacts using the same projectile and energy until full perforation was achieved. During each test, the impact response characteristics, contact force, velocity, displacement and energy absorption with respect to time were measured and recorded. The results show that, for a single impact test, the absorbed energy increases significantly at low impact energies, while repeated impacts lead to a decrease in the values of peak force and stiffness of the composite panels. Here, up to 5 times of energy can be absorbed over multiple low energy impacts compared to that required to perforate the target with a single impact. For multiple impacts at different impact energy levels, accumulation of damaged area increases rapidly around the impact location up to perforation failure (e.g. the rate of damage from 2 mm2 per impact at 1 J case jumping to 25 mm2 per impact at 2 J case, further to 68 mm2 per impact at 3 J case). The rate of damage progression (per impact) appears to be related strongly to the rate of energy absorption. The continuous nature of the absorbed energy and damage progression over multiple impacts suggest that semi-empirical analytical relationships, similar to that used in a fatigue analysis, could be useful in providing a means of assessing impact damage in a laminated structure and predicting the remaining ‘impact fatigue’ life.

Stiffness and damping characteristics of jointed rocks under cyclic triaxial loading subjected to prolonged cyclic loading

A modelled rock joint set featuring a rough joint surface inclined at 60° was fabricated, and cyclic triaxial and conventional monotonic triaxial experiment series were carried out at various confining stresses. Cyclic deviatoric loading was applied up to 500,000 cycles at 8 Hz frequency to evaluate the impact of prolonged repeated loading on the stiffness and damping properties of rock joints and their variation with irreversible axial strain. The analysis of the experimental data revealed that, under the tested conditions, the accumulation of irreversible axial strain exhibited a progressive rise as the repeated loading advanced, particularly in the early stage of deformation. Furthermore, the resilient moduli demonstrated a downward trend in relation to cumulative irreversible axial strain, while the damping ratio showed a rapid decrease initially and then increased slowly with cumulative irreversible axial strain. Moreover, with the rise in confining stress, the accumulated irreversible axial strain reduced while resilient moduli and Young’s moduli increased, and the damping ratio decreased. Through nonlinear regression analysis, empirical relationships for the resilient moduli variation with the irreversible axial strain and variation of critical dynamic irreversible axial strain with cyclic stress ratio were developed.

Department of Pharmacology of the Military Medical Academy in the 21st century: New achievements based on historical traditions (2000–2023)

In the early 2000s at the Department of Pharmacology, active research was launched into the mechanisms of hypoxia, creation of antihypoxic drugs, study of means and technologies for increasing performance, and drugs with immunomodulatory and reparative effects. The mechanisms of hypoxia and life support in extreme conditions have been a traditional area of scientific research of the department. Starting back in the 1960s under the leadership of V. M. Vinogradov, this direction gained development and scientific recognition by the end of the 1990s. During this period, new antihypoxants of direct and indirect actions were created and thoroughly studied, namely, gutimin, bemithyl, amtizol, trimetazidine, and others. Nearly all employees of the department and numerous applicants for academic degrees from among both academic and nonacademic employees participated in the research. The use of approaches and concepts of molecular physiology and pharmacology achieved very interesting and promising results for implementation. An unconditional success in scientific research in this area has been the elucidation of the molecular mechanisms of action of aminothiol-type antihypoxants, which consist in optimizing energy production and energy consumption in cells and the ability of compounds to reduce membrane damage caused by lipid peroxidation and clearly activate antioxidant systems. The second direction was the study of the molecular mechanisms of sustainable adaptation to various factors, which was started by Prof. A. V. Smirnov. Thus, long-term adaptation patterns were established in the body’s adaptation to high-altitude hypoxia, overheating, and heavy repeated loads. The contribution of individual organs to the development of these adaptive phenomena was quantitatively determined. In the experiment, effective schemes for emergency adaptation were developed using “pulse modes” of training influences against the use of pharmacological adaptogens. A significantly more pronounced adaptogenic activity has been established for drugs such as thiobenzimidazole (bemythyl) and trecrezan in comparison with known adaptogens, such as dibazole and eleutherococcus. Based on experimental data, similar schemes for pharmacologically enhanced and accelerated emergency adaptation have been developed and tested on healthy volunteers, particularly to sharp changes in climatic conditions (overheating, hypothermia, and hypoxia) and metabolic cocktails based on the antihypoxant bemityl (B-100, B-200, and B-300). These schemes and pharmacological interventions make it possible, in just a few days, to make the body noticeably adapt to the action of certain climatic factors. The third direction was the creation and study of new pharmacological agents for the correction of the effects of hypoxia, toxic pulmonary edema, and liver and immune system damage based on condensed indole systems and their product transformations. Consequently, indole derivatives (approximately 60 compounds have been synthesized and studied) are low toxic and have antihypoxic, antiedema, hepatoprotective, actoprotective and antiviral activities.