Stiffness Of Specimens Research Articles

Fatigue fracture mechanics in gold-based MEMS notched specimens: experimental and numerical study

The characterization of fatigue fracture mechanics in gold-MEMS notched specimens is presented in this work. A test microstructure with a central notched specimen is specifically designed and built to perform on-chip fatigue test. The central specimen undergoes cyclic loading due to the application of alternating voltage. The variation in the microstructure deflection is measured using an optical profilometer and is attributed to the crack growth in the gold material, causing the variation in the specimen stiffness. The occurrence of pull-in condition is used as a fracture detector, then the fracture of the specimen can be recognized without performing scanning electron microscope inspections during the fatigue test. Crack propagation in the test specimen is simulated through a coupled-field electromechanical fracture finite element model and the resulting crack path is compared to the experimental measurments performed with scanning electron microscope analyses. Finally, Paris’ law is applied and the number of cycles to failure is computed by exploiting the results of the fracture model and experimental measurements. Both experimental and numerical results demonstrate that the notch acts as a stress and strain raiser, fostering crack nucleation, and that the linear elastic fracture mechanics theory is still valid to describe crack propagation in micro-size samples.

Experimental study on the plastic hinge region of precast segmental bridge piers strengthened by CFRP

In this study, three precast segmental pier specimens with a scale ratio of 1:5 were fabricated, and the responses of these pier specimens were studied under cyclic loading. The first reinforced concrete pier specimen (Specimen 1) had no strengthening measures or initial damage; the second pier specimen (Specimen 2) was strengthened by carbon fiber reinforced polymer (CFRP) without initial damage; finally, the third pier specimen (Specimen 3) was first tested to moderate damage, then the damaged plastic hinge region repaired by CFRP was tested for the second time. It was observed that the drift ratio, horizontal load capacity, total cumulative energy dissipation and initial stiffness of Specimen 2 were increased by 75%, 0.71%, 115% and 8.23%, respectively, compared with Specimen 1. The same performances of Specimen 3 after repairing were improved by 25%, 0.64%, 47% and 4.29%, respectively, compared with Specimen 1. Therefore, CFRP can be used for pre-seismic strengthening and post-seismic repair of precast segmental piers, providing reference for engineering application. In addition, it was found that the damage was transferred out of the strengthened region due to the confinement effect of CFRP.

Tensile properties of sandwich-designed carbon fiber filled PLA prepared via multi-material additive layered manufacturing and post-annealing treatment

Abstract Polylactic Acid (PLA) experiences widely spread applications in Fused Filament Fabrication (FFF) owing to its relatively high stiffness, strength, and environmentally friendly biodegradability. Reinforcing inclusions like short carbon fibers are introduced to virgin PLA feedstock aiming to improve the mechanical performance of FFF-made products. Nevertheless, the rigid fibers significantly reduce the ductility of the overall fabricated parts. This study prepares sandwich specimens with PLA as core and its 10 wt% chopped carbon fiber reinforced composites (i.e., CF/PLA) as shell via a low-cost FFF-based multi-material additive layered manufacturing method. The sandwich specimen has three layers, which are changed according to different material volumes, which is able to design the local strength and toughness performances of a printed part. Tensile properties of these sandwich samples printed in the different volumetric rates of virgin PLA constituents are measured. It is found that the strength of sandwich specimens with 20% vol of PLA reduces noticeably as compared to the full CF/PLA specimens. The 80% vol specimens exhibit a competitive strength as compared to the 40% and 60% vol specimens, while its toughness increases notably as compared to the other cases. Finite element simulations of the layered manufacturing process show that the thermal residual stresses of 20% vol sandwich accumulates most significantly. We also explore the effects of thermal annealing on the prepared sandwiches. Experimental results indicated that the post-annealing process improved the strength and stiffness of the sandwich specimens, while enhancing the stability of the mechanical properties of the FFF printed sandwich.

The Role of Dissipated Energy and Stiffness in Enhancing the Fatigue Life of Asphalt Concrete under Environmental Influence

Variation of environmental conditions exhibits various modes of failure of asphalt concrete pavement. Under cold environment, the flexible pavement experience cracking and disintegration, while under hot environment, the pavement practices rutting. Both environmental conditions can enhance the fatigue life of the flexible pavement. In the present work, the role of the change in the dissipated energy, and flexural stiffness of asphalt concrete on its fatigue life under environmental influence have been investigated. Asphalt concrete mixtures were prepared with its optimum asphalt binder requirements, and then compacted into a slab mold by laboratory roller to a target density. Beam specimens were obtained from the prepared slab samples and tested for fatigue life using three levels of constant strain of (750, 400, and 250) microstrain under dynamic flexural stresses. The specimens were tested at (5, 20, and 30) ℃ environment levels. It was noticed that specimens practicing cold environment exhibit shorter fatigue life as compared with those tested at hot environment. However, the flexural stiffness of the beam specimens decline as the testing temperature rises. Such behavior was further supported with the variation in the dissipated energy among testing environment. It was concluded that higher testing environment declines the flexural stiffness, increases the fatigue life, and changes the mode of failure of asphalt concrete from brittle to plastic mode.

A Critical Assessment of the Effect of Initial Fabric on Key Small-Strain Design Parameters of Slurry-Deposited Silts and Sands

Whereas moist-tamped specimens of silts and sands are most used in engineering practice to characterize tailings, offshore sediments, and fluvial/alluvial deposits, design parameters derived from moist-tamping data sets can be significantly different from those obtained from slurry or underwater deposition. This study shows that moist-tamped silty and sandy specimens may exhibit phase transformation at stress ratios that are 25% to 50% lower than those observed for slurry-deposited specimens. Conversely, the small-strain stiffness of the moist-tamped specimens tested can be 50% higher than those from slurry deposition. With tailings dams’ performance receiving increased worldwide attention due to recent dam failures in several parts of the world, this study provides new, specific, and concerning insights about the crucial impact that the selection of moist tamping can have on design parameters. More realistic and rigorous laboratory testing procedures involving tailings remain a key requirement for engineering assessments of tailings behavior. A novel slurry-deposition setup is presented that allows underwater reconstitution of silts, sands, and their mixtures, yielding high-quality uniform specimens. Systematic uniformity checks, which are mandatory to avoid segregation of silty materials, are described. A detailed analysis of typical errors affecting initial void ratio evaluation is also presented to ensure that comparisons between different methods are done with the highest degree of confidence possible.

Local compression behavior of UHPFRC: Experiments and bearing capacity calculation model

To evaluate the mechanical properties of the anchorage zone of prestressed UHPFRC structure, an experimental study was conducted on 54 UHPFRC specimens with central channels using local pressure tests. The local compression bearing capacity and load–displacement relationship were obtained. The experimental results indicated that there were four stages of local compression behavior in specimens: compaction, elastic deformation, crack development in the peripheral concrete and its interface with the wedge, and failure. The local compression cracking load of UHPFRC specimens was generally 40%-80% of the ultimate load. The local compression area ratio had a large effect on the vertical stiffness of UHPFRC local compression specimens. The increase in steel fiber length-diameter ratio (from 65 to 80) improved the transverse flexibility of the specimens. The average increases of UHPFRC local compression cracking load and ultimate load were up to 18.81% and 10.04% when the steel fiber volume content increases from 1% to 3%. The increase of the local compression area ratio on the local compression bearing capacity of UHPFRC ranged from 0.10% to 30.93%. Finally, the analytical formula was proposed to calculate the local compression bearing capacity of UHPFRC by fully considering the effect of the tensile strength of UHPFRC on the hooping action of peripheral concrete. This research provided a novel insight into the accurate bearing capacity calculation methods for UHPFRC in anchorage zones.

Mechanical properties of energy sustainable round bamboo - Phosphogypsum composite floor slabs

Round bamboo is a natural building material with excellent mechanical properties and has broad application prospects in green buildings. To realize the protection of round bamboo and promote the resource utilization of phosphogypsum, a kind of round bamboo-phosphogypsum composite (BPC) floor slab is proposed in this paper. To study the flexural performance of the round bamboo-phosphogypsum composite floor slabs, considering the factors of the thickness of the phosphogypsum, the number of dovetail nails, the number of round bamboo poles and the span, the flexural tests of 11 floor slabs were carried out, the influence of the factors on the flexural performance of the floor slabs was analyzed, and the calculation methods of the flexural stiffness and bearing capacity of the floor slabs were established. The results show that the bearing capacity, ductility coefficient and flexural stiffness of the control specimen are increased by 31.26%, 51.19% and 3.39 times compared with the bamboo skeleton. The ductility and flexural stiffness of the floor slab decrease with increasing span. The bearing capacity of floor slab increases with the increasing bamboo number and decreasing span. The calculation methods of flexural performance of the floor slabs established in this paper have certain accuracy. The round bamboo-phosphogypsum composite (BPC) floor slab realizes the efficient utilization of resources, which has reference significance for green buildings and sustainable development.

Seismic performance of corroded non-seismically and seismically detailed RC beam-column joints rehabilitated with High Strength Fiber Reinforced Concrete

The experimental investigation was undertaken to restore the seismic performance of the corrosion-damaged beam-column joint (BCJ) rehabilitated with High Strength Fiber Reinforced Concrete (HSFRC). A total of eight exterior beam-column sub-assemblages were cast following two types of reinforcement detailing as per IS 456:2000 and IS 13920:2016, respectively. Three specimens from each reinforcement detailing regime were subjected to three different levels of corrosion and thereafter rehabilitated with HSFRC. The hysteresis behavior, energy dissipation, stiffness degradation, crack patterns, and damage index of all rehabilitated specimens are analyzed and compared with the conventional specimens. Test results indicate that the replacement of damaged concrete with HSFRC can recover the strength of corrosion-damaged BCJ when the corrosion ratio is within 10 %. The peak load-carrying capacity and initial stiffness of rehabilitated specimens showed a significant increase up to 36 % and 84 % respectively, when compared to control specimens. The ductile detailing rehabilitated specimens showed up to 90 % higher equivalent viscous damping ratio than the non-ductile ones, exhibiting close stirrups arrangement superiority. Despite recovering the load-carrying capacity at initial drifts, the seismic performance of non-ductile and ductile rehabilitated specimens having 17.76 % and 20.32 % corrosion ratio were not recovered at higher drifts.

Flexural Behavior of Corroded Concrete Beams Strengthened with Carbon Fiber-Reinforced Polymer.

The present study investigates the flexural behavior of reinforced concrete (RC) beams; the longitudinal reinforcing rebars of the beams were corroded and then strengthened with carbon fiber-reinforced polymer (CFRP). The corrosion of the longitudinal tension reinforcing rebars in eleven beam specimens was accelerated in order to obtain different corrosion levels. Afterwards, the beam specimens were strengthened by bonding one layer of CFRP sheets to the tension side to restore the strength loss due to the corrosion. The failure modes, flexural capacity, and midspan deflection of the specimens with different corrosion levels of the longitudinal tension reinforcing rebars were obtained by the four-point bending test. It was found that the flexural capacity of the beam specimens decreased with the increase in the corrosion level of the longitudinal tension reinforcing rebars and that the relative flexural strength was only 52.5% when the corrosion level was 25.6%. The stiffness of the beam specimens decreased significantly when the corrosion level was higher than 20%. Through a regression analysis of the test results, a model for the flexural bearing capacity of the corroded RC beams strengthened with CFRP was proposed in the study.

Shear resistance and deflection prediction of steel–concrete–steel sandwich panel with headed stud connectors

Bending tests were conducted on eight specimens to investigate the mechanical behavior of steel–concrete-steel (SCS) sandwich panels with headed studs, taking into account the effects including loading mode, steel plate thickness, concrete core thickness and connectors spacing, and one sandwich panel was used as a control specimen. The failure characteristics and crack patterns of the specimens were recorded and the vertical displacement in the span was measured. The test results were used for the validation of the finite element model (FEM). Further parametric studies of the FEM yielded the effect of steel plates on the load-bearing capacity of the sandwich structure. Analytical models applicable to the initial stiffness and shear resistance of specimens with headed studs were proposed. The shear strength considered the effect of steel plate and pin action. The deflection calculation models of the sandwich panel were obtained based on the energy method and were in good agreement with the load–displacement response curves obtained by FEM results. The research results of this paper will have an impact on the large deformation and ultimate strength prediction of sandwich protective panels.

Reliable Methods for Classification, Characterization, and Design of Cellular Structures for Patient-Specific Implants.

In our research, our goal was to develop a characterization method that can be universally applied to periodic cell structures. Our work involved the accurate tuning of the stiffness properties of cellular structure components that can significantly reduce the number of revision surgeries. Up to date porous, cellular structures provide the best possible osseointegration, while stress shielding and micromovements at the bone-implant interface can be reduced by implants with elastic properties equivalent to bone tissue. Furthermore, it is possible to store a drug inside implants with a cellular structure, for which we have also prepared a viable model. In the literature, there is currently no established uniform stiffness sizing procedure for periodic cellular structures but also no uniform designation to identify the structures. A uniform marking system for cellular structures was proposed. We developed a multi-step exact stiffness design and validation methodology. The method consists of a combination of FE (Finite Element) simulations and mechanical compression tests with fine strain measurement, which are finally used to accurately set the stiffness of components. We succeeded in reducing the stiffness of test specimens designed by us to a level equivalent to that of bone (7-30 GPa), and all of this was also validated with FE simulation.

Shear performance of the epoxy-bolt interface between UHPC slabs and GFRP girder

The shear performance of the epoxy-bolt interface between ultrahigh-performance concrete (UHPC) slabs and glass fibre-reinforced polymer (GFRP) girder was evaluated via push-out tests. A total of thirteen GFRP-concrete push-out specimens, including eleven GFRP-UHPC specimens with an epoxy-bolt interface, one GFRP-UHPC specimen with a bolt interface and one GFRP-normal-strength concrete (NSC) specimen with a bolt interface, were compared. Experimental parameters included the concrete strength, interface type, bolt spacing (sbolt), bolt-embedding length (hbolt), bolt number (nbolt), bolt diameter (dbolt) and bolt strength (σbolt). The test results revealed four failure modes, i.e., debonding of the epoxy layer, bolt shank shear failure, GFRP flange shear-out failure and concrete failure. Compared to the GFRP-UHPC specimen with a bolt interface, the bearing capacity and shear stiffness of the GFRP-UHPC specimen with an epoxy-bolt interface were approximately 10% and 40% higher, respectively, and the ultimate slip was approximately 3.5% lower. The employment of the UHPC slab substantially improved the shear stiffness by 19% compared with the GFRP-NSC push-out specimen. The nbolt, dbolt and σbolt showed a positive influence on the bearing capacity, whereas the hbolt showed a negative influence. The epoxy-bolt interface was recommended in the GFRP-UHPC hybrid beams to improve the composite action. Finally, the bearing capacities of the GFRP-UHPC push-out specimens with the epoxy-bolt interface were predicted.

Prediction of the mechanical performance of compressed circular CFST columns with circumferential debonding gap

Concrete-filled steel tubular (CFST) structures have been widely used in high-rise buildings and long-span bridges for the high strength and ductility due to the confinement effect of the concrete core provided by the steel tube. This beneficial composite action could be damaged by circumferential debonding gap (CDG), which is nearly unavoidable in real CFST structures. Reliable formulations to predict the influence of CDG on the mechanical performance of compressed circular CFST columns are needed. In this paper, the experimental parameters and results of compressed circular CFST columns with CDG are summarized to discuss the deficiencies of the parameters chosen in the tests. Detailed finite element simulation procedures for compressed circular CFST columns with CDG, based on ABAQUS, are then introduced, verifying their accuracy by test results. Based on the validated finite element models, a database of compressed circular CFST columns with and without CDG, including strength, ductility and stiffness of specimens is established; it is obtained by covering suitable parameter ranges for CDG and CFST structures, in accordance with real applications. Successively, new formulations able to predict the ultimate load capacity, the reduction factor, the ductility and the stiffness of specimens are derived by the Evolutionary Polynomial Regression (EPR) methodology, demonstrating good accuracy and low complexity.

Effect of different load levels on the flexure performance of RC beams exposed to fire

The paper presents the effect of different load ratios on the thermal and flexural behaviour of RC beams during and after fire. Full scale beam specimens of normal strength concrete of dimensions 230 mm × 400 mm × 4000 mm were exposed to design fire curves for the same duration under load ratios of 0.0, 0.20 and 0.40 of the ultimate load. Finally the beams were mechanically loaded till failure to estimate the residual capacity after cooling. The results showed that with the increase in the pre-load during fire alters (a) the thermal profile of the specimens (b) The performance of the beam specimens and (c) The ultimate capacity and flexural stiffness of the beam specimens after fire. A numerical model was also proposed to validate the experimentally obtained results..

FULLY CHARACTERIZING SPINAL LOAD DISPLACEMENT BEHAVIOUR USING VISCOELASTIC MODELS

Lower back pain (LBP) is a global problem. Countless in vitro studies have attempted to understand LBP and inform treatment protocols such as disc replacement devices (DRDs). A common method of reporting results is applying a linear fit to load-displacement behaviour, reporting the gradient as the specimen stiffness in that axis. This is favoured for speed, simplicity and repeatability but neglects key aspects including stiffening and hysteresis. Other fits such as polynomials and double sigmoids better address these characteristics, but solution parameters lack physical representation. The aim of this study was to implement an automated method to fit spinal load-displacement behaviour using viscoelastic models.Six porcine lumbar spinal motion segments were dissected to produce isolated disc specimens. These were potted in Wood's metal, ensuring the disc midplane remained horizontal, sprayed with 0.9% saline and wrapped in saline-soaked tissue and plastic wrap to prevent dehydration. Specimens were tested using the University of Bath spine simulator operating under position control with a 400N axial preload.Specimens were approximated using representative viscoelastic elements. These models were constructed in MATLAB Simulink R2020b using the SimScape library. Solution coefficients were determined by minimizing the sum of squared errors cost function using a non-linear least squares optimization method.The models matched experimental data well with a mean % difference in model and specimen enclosed area below 6% across all axes. This indicates the ability of the model to accurately represent energy dissipated. The final models demonstrated reduced RMSEs factors of 3.6, 1.1 and 9.5 smaller than the linear fits for anterior-posterior shear, mediolateral shear and axial rotation respectively.These nonlinear viscoelastic models exhibit significantly increased qualities of fit to spinal load-displacement behaviour when compared to linear approximations. Furthermore, they have the advantage of solution parameters which are directly linked to physical elements: springs and dampers. The results from this study could be instrumental in improving the design of DRDs as a mechanism for treating LBP.

Theoretical and Experimental Study on Normal Contact Stiffness of Plane Joint Surfaces With Surface Texturing

Effects of surface texturing on normal contact stiffness have been investigated by experiments in previous research studies; however, there are relatively few theoretical models in this regard. This article aims to investigate the influence of surface texturing on the normal contact stiffness in theory and experiment. In the present research, a rough surface with surface texturing is divided into two parts, the textured zone and the remaining zone, and their theoretical models of normal contact stiffness are established respectively, considering surface morphology and material properties. For the textured zone, microtextures are modeled theoretically based on the three-dimensional topographic data obtained via a laser profilometer. For the remaining zone, the surface topography is characterized based on fractal theory, and a calculation model is established considering the elastoplastic deformation of surface asperities. In the experiment, the normal contact stiffness of specimens is obtained through the self-developed experimental platform. The proposed theoretical model is appropriate through the comparison of test results and theoretical predictions. The research results show that the effect of surface texture on the contact stiffness is related to the surface roughness, Sa. For the joint surfaces with Sa > 2.69 μm, the normal contact stiffness can be effectively increased through proper surface texturing.

Fabrication, design, and optimization of hierarchical composite Kagome honeycomb sandwich structure under uniaxial compression

Abstract In this study, a hierarchical composite Kagome honeycomb sandwich (HCKHS) structure was manufactured based on the interlocking method, and its uniaxial compression performance was explored. Through experiments, the compressive strength, stiffness, energy absorption, and failure process of HCKHS specimens of seven different sizes were determined and compared. Mechanical analytical models were established, and the variation trend in the specific strength was predicted and compared with those of other advanced sandwich structures. The size effect of the HCKHS specimens was analyzed. The influence of a single variable on the core modulus, failure strength, and failure modes was discussed, and failure mechanism maps were drawn. The structure was optimized based on the maximum specific strength and engineering application, and the optimal size design ratio was obtained. The results showed that the HCKHS specimens exhibited excellent compressive properties with a convenient manufacturing process, making them suitable for lightweight applications in engineering. The optimization ideas presented herein are also applicable to other two-dimensional hierarchical or normal composite honeycomb sandwich structures with diamond, triangular, and hexagonal shapes.

Seismic behavior of steel plate wall with stiffeners and concrete slab in the box-plate steel structure

The box-plate steel structure is a box-type building in which stiffened steel plates are directly used as load-carrying walls and floors. The seismic behavior of the stiffened steel plate walls (SSPWs) in the box-plate steel structure is the key to ensuring the safety of the box-type building when it is used in a seismic precautionary zone. In order to improve the seismic behavior of the SSPWs in the box-plate steel structure, precast concrete slab is set on the side without stiffeners. Thus formed the steel plate wall with stiffeners and concrete slab in each side (CS-SSPW). In this paper, one SSPW specimen and three CS-SSPW specimens were designed and tested to study the seismic performance of CS-SSPW and to understand to what extent the setting of concrete slabs can improve the load-carrying capacity and seismic performance of SSPW. The quasi-static test results showed that, compared with the SSPW specimen, the load-carrying capacity, energy dissipation capacity, stiffness and deformation capacity of the CS-SSPW specimens were significantly improved. Subsequently, in order to further clarify the force mechanism and failure mode of CS-SSPW, the finite element simulation analysis was carried out on the four specimens, and the finite element analysis (FEA) models were verified by the test results. Moreover, parametric analysis was conducted to investigate the influence of various parameters on shear capacity of the CS-SSPW. Through parameter analysis, the design suggestion of CS-SSPW was given. Finally, based on the results of experiment and FEA, the force mechanism of CS-SSPW was analyzed, and a calculation method was proposed to evaluate the ultimate shear capacity of CS-SSPW which could be used as the design basis for practical engineering.

Long-term mechanical performance of 3D printed thermoplastics in seawater environments

This study investigates the effects of 3D-printed thermoplastics' long-term exposure to ocean water. The work focuses on seawater diffusivity rates and mechanical performance to discuss material candidates for long-term undersea structures. Several commonly available thermoplastics were printed using Fused Deposition Modeling and then submerged in an ocean water solution for a prolonged period at elevated temperatures. The thermoplastics studied included Nylon, ABS, PLA, PCTG, PETG, and ASA. The different temperatures corresponded with distinct accelerated rates of water mass diffusion. The solution's water level, temperature, and salinity were monitored and maintained during the accelerated weathering process. The total mass of each specimen and its elastic modulus were recorded daily using a precision scale and a Dynamic Mechanical Analyzer machine. The change in mass was used to calculate the activation energy of each material system by defining the degradation to have an Arrhenius behavior and using a new polynomial fit-based technique. The new polynomial fit-based method was robust compared to a one-dimensional system that uses Fick's law of diffusion. Results also showed that the 3D printed structures, regardless of their composition, are susceptible to extremely high diffusivity rates compared to their bulk material behavior. Lastly, mechanical properties decreased for all polymers, and the stiffness of the aged specimens was proportionally affected by the change in mass.

In-plane/out-of-plane seismic performance of masonry infilled RC frame structure made of nano-SiO2 reinforced mortar: Experimental study

Due to the seismic vulnerability of conventional masonry infill wall Reinforced Concrete (RC) frame buildings, which caused the infill wall structure to break and collapse, resulting in serious casualties and property damage. It was necessary to fully understand the action mechanism and seismic strengthening of the infill wall structure. Considering that few researches had paid attention to the effect of mortar performance on the seismic behaviors of infill wall structure, this study was the first to use a nano-SiO2 (NS) reinforced mortar to construct masonry infill wall RC frame structure. The pure out-of-plane (OOP) and in-plane and out-of-plane (IPOOP) loading tests were conducted to validate the structure's seismic performance. The experimental results of comparison with ordinary mortar specimen were shown. Due to the mitigation of the cracking of wall in pure OOP test, the initial stiffness, load-bearing capacity and ultimate displacement of new mortar specimen were increased by 65.88%, 23.57% and 11.12%, respectively. However, both infill wall specimens exhibited the similar cracking characteristics and load-displacement response, those indicated that the improvement in mortar performance was not sufficient to change the failure mode. In the in-plane (IP) tests, the infill walls constructed with new mortar provided a better diagonal bracing mechanism, resulting in a 13.32% and 12.67% increase in the IP load-bearing and energy dissipation capacity. The less side shear cracking of infill wall caused stiffness degrades more slowly. In the IPOOP tests, at approximately the same previous IP damage level, the slower propagation of crack resulted in a slower reduction in the load-bearing capacity and an increase in the deformability during subsequent OOP loading. Therefore, the application of the new mortar improved the shear and bond strength of the members, which mitigated IP damage and improved the stability of the wall, while slowed down the OOP cracking of the wall and reduced the risk of collapse.