Face Of Wall Research Articles

Utilization of Cold-Formed Steel-Framed Emergency Shelter for Typhoon Reliefs in the Philippines

The destructive aftermath of storms and typhoons in the Philippines more prominently affects isolated remote locations that lack methodical and strategic procedures to address the situation. One form of assistance provided during disasters is the construction of shelters, which can be categorized as emergency, temporary, or transitional, serving as protection during recovery periods. Cold-formed steel (CFS) is widely used, and its versatility in fabrication and configurability make it an ideal candidate for building emergency shelters that are lightweight, easy to assemble, upgradeable, and cost-effective. This research aims to address gaps in existing modalities for emergency shelters during typhoon disasters through proposing an alternative design that uses CFS based on internationally accepted standards. The methodology is divided into three (3) phases, namely (1) analytical design and modeling, (2) cost sustainability assessment, and (3) shelter implementation plan. Three (3) different configurations with 4, 6, and 8 studs per wall face were designed and optimized using Midas Gen based on governing wind loads. The final frame design consisted of fully cross-braced along the failing direction, with an increase in uniform thickness of members. All of which checked for adequacy and connections designed accordingly. The overall cost was quantified lower than that of the traditionally used shelter design in terms of cost, covered area, and lifespan by a significant margin. All important information and findings are aligned in an original shelter implementation manual to ensure the shelter is aligned with the current situation in the Philippines.

Connection performance by frictional resistance at the gabion wall facing and geosynthetics reinforcements

Connection performance by frictional resistance at the gabion wall facing and geosynthetics reinforcements

Numerical Modeling of Cantilever Retaining Wall Using EPS Geofoam

Earth retaining wall structures are common civil engineering structures. Estimation of magnitude and distribution of earth pressure on retaining structures under different surcharge loading conditions is essential as they influence the design and overall economy of retaining structures. Numerical modeling using finite element code PLAXIS is used static analysis. 7 m height of non-yielding cantilever retaining wall with and without EPS geofoam structure is studied and 20 m backfill width was considered. In the present study backfill was modeled as Mohr-Coulomb yield criteria and EPS geofoam and wall were modeled as Linear-elastic. EPS geofoam densities namely 12 kg/m3 and 15 kg/m3 and two different geofoam thicknesses 0.107H and 0.143H were used for static analysis. Three different surcharge loading namely 10 kPa,30kPa and 50kPa which were kept at a distance of 2.0 m away from the wall face. In the static analysis earth pressure distribution for wall with and without geofoam were analyzed. Approximately 50% isolation efficiency was reported. At lower surcharge loads the effectiveness of EPS is more as compare to higher surcharge load and with increase in surcharge load, isolation efficiency gradually decreases and isolation efficiency decreases with increase in buffer modulus. Apart from these serviceability criteria was also checked. Serviceability criteria comprise of lateral deformation of EPS geofoam at sand-geofoam interface and backfill surface settlement were studied. Lower EPS geofoam density and higher EPS geofoam thickness reduces higher magnitude of earth pressure but in this combination the backfill surface settlement was coming very high.

Centrifuge model tests on performance of MSE walls with different facing types

The role of wall facing is crucial in the design of MSE walls. This study employed two centrifuge model tests specifically designed to analyze walls with two distinct facing types: full-height panel facing and modular block facing. Additionally, surcharge loads were applied to these MSE walls to simulate real-world conditions. The findings from these tests revealed that MSE walls with full-height panel facing exhibited superior performance under the combined effects of self-weight and surcharge loads. The measured maximum horizontal displacements in walls with full-height panel facing and modular block facing were about 55% and 85% of those predicted from current design guidelines at EOS3, respectively. The influence of the surcharge loads on the reinforcement loads was found to be substantial for both wall types, especially for the case of model wall with modular block facing, where the reinforcement loads in the upper half of the wall increased by about 30% from EOS2 to EOS3. The insights garnered from this study contribute to a deeper and more nuanced understanding of the impact of facing types on the practical construction and design of MSE walls, offering valuable guidance for future engineering applications.

Mechanical Behavior of Geogrid Flexible Reinforced Soil Wall Subjected to Dynamic Load

The geogrid flexible reinforced soil wall is widely used in engineering practice. However, a more comprehensive understanding of the dynamic behavior of reinforced soil wall is still required for a more reasonable application. In order to explore the mechanical behavior of a geogrid flexible reinforced soil wall, the model test was carried out to investigate the dynamic deformation of geogrid reinforced soil wall subjected to a repeated load. The numerical simulation was also conducted for comparison and extension with regards to the earth pressure and the reinforcement strain. The change rules for the deformation of the wall face, the vertical earth pressure and the reinforcement strain subjected to dynamic load with four frequencies (4, 6, 8 and 10 Hz) and four amplitudes (30–60, 40–80, 50–100 and 60–120 kPa) were obtained. The factors that affect the mechanical behavior of geogrid flexible reinforced soil wall were analyzed. The results show that the dynamic deformation characteristics of reinforced soil wall are affected by the number of vibrations, the amplitude of dynamic load and the frequency of vibration. The maximum lateral displacement of the reinforced soil wall occurs on the third to the fifth layer. With an increase in dynamic load amplitude, the development of dynamic deformation gradually increases, and after a cumulative vibration of 200 × 104 times, the cumulative lateral deformation ratio and the cumulative vertical deformation ratio of the wall face is less than 1%. The vertical earth pressure of geogrid flexible reinforced soil wall increases partially along the length of the reinforcement, and the vertical earth pressure of the third layer is basically unchanged when subjected to a dynamic load. With an increase in vibration number, the change in the reinforcement strain of the third layer is more complex, and the change rules of the reinforcement strain of each layer are different. The reinforcement strain is small, with a maximum value of 0.1%.

Evaluation of dynamic soil stress distribution in GRS bridge abutments subjected to cyclic loading

Traffic-induced cyclic loading generates repetitive stresses and cumulative deformations on the GRS abutments, which affect the serviceability of GRS abutments. To evaluate the stress distribution of GRS abutments under cyclic traffic loading, this paper presents reduced-scale GRS abutment models constructed with sand backfill and geogrid reinforcements. The GRS abutment models were subjected to staged cyclic loading with different cyclic loading amplitudes to investigate the influences of cyclic loading amplitude, bridge superstructure load, and reinforcement vertical spacing on the dynamic soil stress distributions. The results indicate that the increase in residual stresses due to stress redistribution induced by cyclic loading is most pronounced at the top of the abutment, while there is little stress redistribution down to the foundation level. Increasing the static load of bridge superstructure or the amplitude of cyclic loading results in an increase in the incremental dynamic vertical soil stresses. Reinforcement vertical spacing does not significantly impact the incremental dynamic vertical soil stresses under cyclic loading, while the cyclic load has the most significant influence. Closer reinforcement vertical spacing could provide stronger lateral confinement, resulting in larger dynamic lateral soil stresses behind wall facing.

Numerical investigation on the behaviour of Post-Tensioned Mechanically Stabilised Earth Walls (PT-MSEW)

This study reports on a numerical investigation on the behaviour of an innovative retaining wall system named Post Tensioned Mechanically Stabilised Earth Wall (PTMSEW). In the proposed system, Post-Tensioning (PT) technique was integrated into the common retaining wall and the Mechanically Stabilised Earth Wall (MSEW) construction method to improve the performance of MSEWs and limit their failure modes. The variables of this study were wall height, PT force, pre-cast segment size, surcharge load, foundation size, and soil reinforcement length. The study found that incorporating PT stress into the MSEW improved the performance of the retaining wall by decreasing horizontal displacement of the wall face, soil reinforcement tensile forces, and backfill settlements and significantly enhanced the passive resistance of the wall. The introduction of a small amount of PT force prevented local failures caused by the relative movement of face segments. It was observed that by applying only a small level of post-tensioning, the lateral load-carrying capacity and passive resistance of the proposed PT-MSEW system can be significantly improved over that of its conventional counterpart. This opens new possibilities for the use of MSEW in the construction of taller retaining walls.

Radiative cooling and indoor light management enabled by a transparent and self-cleaning polymer-based metamaterial

Transparent roofs and walls offer a compelling solution for harnessing natural light. However, traditional glass roofs and walls face challenges such as glare, privacy concerns, and overheating issues. In this study, we present a polymer-based micro-photonic multi-functional metamaterial. The metamaterial diffuses 73% of incident sunlight, creating a more comfortable and private indoor environment. The visible spectral transmittance of the metamaterial (95%) surpasses that of traditional glass (91%). Furthermore, the metamaterial is estimated to enhance photosynthesis efficiency by ~9% compared to glass roofs. With a high emissivity (~0.98) close to that of a mid-infrared black body, the metamaterial is estimated to have a cooling capacity of ~97 W/m2 at ambient temperature. The metamaterial was about 6 °C cooler than the ambient temperature in humid Karlsruhe. The metamaterial exhibits superhydrophobic performance with a contact angle of 152°, significantly higher than that of glass (26°), thus potentially having excellent self-cleaning properties.

Distinct Element Method Analyses for Damage Assessment: The Northern Spur of Valverde Bulwark in the Venetian Fortress of Bergamo

ABSTRACT The 16th century Venetian Fortress, with more than 70,000 m2 of masonry wall facing, characterises the city landscape of Bergamo. Almost intact and well preserved, the defensive system was inscribed on the UNESCO World Heritage List in 2017. Today, the first causes of its deterioration are the vegetation growth and the lack of maintenance, which have led to instabilities and local failures, particularly in the northwest portion. Thus, in 2019 and 2020, survey campaigns were carried out to assess the safety of one of the most damaged sections, the Valverde bulwark. The survey combines on-site observations, laboratory tests, and photogrammetric and laser scanner surveys to describe the bulwark. Numerical simulations have been performed using a distinct element approach, i.e. assimilating the masonry to a system of discrete bodies consisting of blocks (usually rigid) interacting on their interfaces. A routine dedicated to defining a real-like geometrical model has been developed. The numerical analyses were run to assess the conditions of the Valverde bulwark under self-weight and earth pressure and considering seismic load. Through the detailed survey and its automatic digitisation, it is possible to fully recognise and analyse the state of health of these historic structures and their mechanical behaviour.

Superoxide signalling and antioxidant processing in the plant nucleus.

The superoxide anion radical (O2·-) is a one-electron reduction product of molecular oxygen. Compared with other forms of reactive oxygen species (ROS), superoxide has limited reactivity. Nevertheless, superoxide reacts with nitric oxide, ascorbate, and the iron moieties of [Fe-S] cluster-containing proteins. Superoxide has largely been neglected as a signalling molecule in the plant literature in favour of the most stable ROS form, hydrogen peroxide. However, superoxide can accumulate in plant cells, particularly in meristems, where superoxide dismutase activity and ascorbate accumulation are limited (or absent), or when superoxide is generated within the lipid environment of membranes. Moreover, oxidation of the nucleus in response to environmental stresses is a widespread phenomenon. Superoxide is generated in many intracellular compartments including mitochondria, chloroplasts, and on the apoplastic/cell wall face of the plasma membrane. However, nuclear superoxide production and functions remain poorly documented in plants. Accumulating evidence suggests that the nuclear pools of antioxidants such as glutathione are discrete and separate from the cytosolic pools, allowing compartment-specific signalling in the nucleus. We consider the potential mechanisms of superoxide generation and targets in the nucleus, together with the importance of antioxidant processing in regulating superoxide signalling.

P-M INTERACTION DIAGRAMS FOR REINFORCED CONCRETE WALLS RETROFITTED WITH EXTERNALLY BONDED CARBON-FIBER REINFORCED POLYMER

This research develops analytical axial load-bending moment (P-M) interaction diagrams for reinforced concrete (RC) walls retrofitted with carbon fiber reinforced polymer (CFRP). A 12-inch thick, 1-foot strip of RC wall section is considered with varying reinforcement ratios, varying axial compressive loading, and varying number of CFRP layers. The CFRP material is treated as externally bonded onto the tension face of the RC wall to investigate its impact on the flexural capacity of the section. Each P-M interaction diagram was generated considering a discretized compression zone and by satisfying principles of static equilibrium and strain compatibility. An elastic-plastic steel stress-strain relationship is used for Grade 60 reinforcement; a uniaxial nonlinear compressive stress-strain relationship is used for concrete; and a linear stress-strain relationship is used for CFRP in tension. The failure modes considered are steel yielding, concrete crushing, and CFRP debonding. The computed P-M interaction diagrams are normalized for their general use in the retrofit of existing RC walls using CFRP. Results show that as the axial compressive force on the RC wall increases, the less effective CFRP is. CFRP is more effective in sections with beam-like behavior, where the reinforcement ratio tends to be the smallest.

Research on a kind of positioning anti-eccentric fixture for measuring thin wall gear with special big inner hole

This paper mainly studies and designs the clamping tool which is installed in the measuring of big gears with big inner holes and thin walls. This paper analyzes the disadvantages of conventional clamping of large gears with special inner holes, and presents an example of the research and development of the Assembly of the mounting and positioning device of the special large inner hole gear based on the gear measuring instrument. At present, in the field of gear measurement, the measurement of large gears is always a technical problem. The technical ability of gear testing in our country is restricted by various factors. Most gear high-precision instruments and their accessories still depend on imports, which cannot be a good solution to the measurement of special gear installation and positioning problems from the economy and timeliness. Especially, large gears with large bores and thin walls face the problem of determining the position of the measuring device and the measured gears, that is, the measuring datum is difficult to determine [1]. This paper proposes how to use the existing gear measuring instrument to develop and use small accessories, so as to help the production enterprises and measuring institutions solve the problem of reference positioning in the actual production measurement process and determine the accuracy of special gear samples.

Physical and Numerical Models of Mechanically Stabilized Earth Walls Using Self-Fabricated Steel Reinforcement Grids Applied to Cohesive Soil in Vietnam

Mechanically stabilized earth (MSE) walls have been widely applied in construction to maintain the stability of high embankments. In Vietnam, imported reinforcement materials are expensive; thus, finding locally available materials for MSE walls is beneficial. This study examines the behavior of an MSE wall using local reinforcement materials in Danang, Vietnam. The MSE was reinforced by self-fabricated galvanized steel grids using CB300V steel with 3 cm ribs. The backfill soil was sandy clay soil from the local area with a low cohesion. A full-scale model with full instrumentation was installed to investigate the distribution of tensile forces along the reinforcement layers. The highest load that caused the wall to collapse due to internal instability (reinforcement rupture) was 302 kN/m2, which is 15 times greater than the design load of 20 kN/m2. The failure surface within the reinforced soil had a parabolic sliding shape that was similar to the theoretical studies. At the failure load level, the maximum lateral displacement at the top of the wall facing was small (3.9 mm), significantly lower than the allowable displacement for a retaining wall. Furthermore, a numerical model using FLAC software 7.0 was applied to simulate the performance of the MSE wall. The modeling results were in good agreement with the physical model. Thus, self-fabricated galvanized steel grids could confidently be used in combination with the local backfill soil for MSE walls.

Analysis of the maximum reinforcement loads of four MSE walls compared to the values predicted by the AASHTO 2020 specification

Mechanically stabilized earth (MSE) systems are a well-known and applicable solution for retaining walls, that presents a composite structure consisting of layers of backfill soil with rigid or flexible reinforcement inclusions. The stability of the wall system is derived from the interaction between the backfill and soil reinforcements involving friction and tension. The wall facing has as its main function to prevent erosion of the structural backfill. The design of MSE walls is usually divided in two phases: external and internal stability. Although there are many methods to design MSE walls, the Coherent Gravity Method is the most common used for MSE walls reinforced with inextensible (steel) reinforcements, the Simplified Method for both steel and geosynthetics reinforced wall systems and the new one included in 2020, Stiffness Method, to calculate the maximum reinforcement loads, Tmax, for extensible (geosynthetics) reinforced MSE walls (all these methods are outlined in Section 11 of the AASHTO LRFD Bridge Design Specifications 2020) . The main objective of this paper is to carry out the analysis of the 3 methods available at AASHTO and compare the results from full-scale MSE walls and the predicted Tmax values.

Analysis of the Influence of External Wall Material Type on the Thermal Bridge at the Window-to-Wall Interface.

Although many works focus on increasing the energy efficiency of buildings, there are still a number of problems that need to be solved, such as reducing heat losses at the window-to-wall interface, especially since the requirements for saving energy used for heating/cooling rooms are constantly increasing. This paper analyses the impact of the material parameters of the external wall and the window installation in the insulation layer on the size of thermal bridges around the window. The aim of the work is to demonstrate the benefits resulting from the correct installation of the window, the appropriate location of the window in relation to the face of the external wall, as well as the correct selection of construction materials. In order to show the improvement in the energy efficiency of buildings, an analysis of the heating/cooling energy consumption was carried out for the selected buildings. The thermal and humidity analyses were carried out using TRISCO program, while the economic analysis was performed using the Audytor OZC program. It was found that the proposed system of window installation in the thermal insulation layer reduced the annual heating demand by at least 10% on average. It has been shown that the method of window installation and the type of the wall structural materials are interrelated and therefore should be considered simultaneously. Their proper selection allows for a reduction in the amount of energy needed for heating and cooling buildings, and thus a reduction of heating/cooling costs, as well as limiting greenhouse gas emissions.

Cyclic tests on two-leaf rubble stone masonry spandrels strengthened with CRM coating on one or both sides

The paper reports the results of an original experimental campaign carried out on full-scale, two-leaf rubble stone masonry spandrels retrofitted using the Composites Reinforced Mortar (CRM) technique, applied on one or both wall faces. The CRM system consisted of a mortar coating reinforced with Glass Fibre-Reinforced Polymer (GFRP) meshes and GFRP transverse connectors to promote the connection with the existing masonry. When the coating was applied on one side, additional transverse connectors, made of grout cores with embedded steel ties (artificial diatons), were also used. These elements further strengthened the connection between the coating and the masonry and connected the leaves of the multi-leaf stone masonry walls.The GFRP mesh in the mortar coating provided the walls with the capacity to resist tension: once the coating and the masonry cracked, the strengthened samples withstood higher distortions, exhibited increased ductility and developed very diffuse crack patterns before collapsing, yielding greater energy dissipation. Furthermore, the transverse connectors enabled the composite action of the CRM coating and the walls and, in the case of artificial diatons, prevented the separation of the masonry leaves.The resistance of the walls with the CRM coating on one and both sides was 2.8 and 3.4 times that of the plain samples, respectively; in both cases, the ultimate drift was more than five times larger than the reference, while the cumulative dissipated energy was more than 30 times. The equivalent hysteretic damping in the damaged state was 11–14% (for CRM on one side) and 8–9% (for both sides).

Numerical investigation on strengthening of brick masonry wall using mortar joint technique

Many parts of the world have used and continued to use brick masonry throughout history. Because of severe earthquakes occurring all over globe time and again, the walls face lots of damage. Hence, it is necessary to study the behavior of masonry walls and provide correct solution to strengthen it. The study is focused on providing a comprehensive review of earlier works, validation of an experimental study in a published paper using numerical analysis, ANSYS Workbench 2021 R2, wherein brick models are strengthened by providing mortar collar joint, for enhancing the load resisting capacity of the structural element. Load- deflection behavior and failure pattern illustrated explains how strength of wall improves using this technique. Also, this paper discusses how change in mechanical properties bring significant amount of change in load resisting characteristics. Cracks and deflection get minimized and load resisting capacity of masonry walls increases upto 24% (minimum).

Numerical Studies on the Reinforced Fly Ash Wall in Tiered Configuration

This paper presents the findings of the numerical studies performed on a two-tiered reinforced fly ash wall. Fly ash was used as backfill material and jute geotextile was used as reinforcement as well as facing material. Wrap-around facing was used in which the jute geotextile was folded at the face. Three-dimensional models of fly ash walls showing offsets at varying distances between the two tiers and the length of reinforcement were prepared. The horizontal displacement on the wall face, tensile forces on reinforcement, and settlement behavior of the backfill wall were analyzed. Further, the wall model was scaled 10 times to generate large-scale fly ash models to understand the behavior of a life-size reinforced fly ash tiered wall. The displacement in the horizontal direction at the face of the wall reduced with the increase in length of the reinforcement and the distance between the tiers. The influence of the offset distance between the tiers on the tensile forces acting on the reinforcement was also investigated. The critical distance between the offsets was identified as 0.6 times the lower tier height. The tiered wall in the present study showed significant reduction in mobilized tensile force in the reinforcements especially at the lower tier as compared with a single (without tier) reinforced fly ash wall of the same height. The maximum tensile force for a single wall was observed to be 1.25 times and 5.35 times the two-tiered wall with D/L = 0.6 for upper and lower tiers, respectively, where D = distance of the offsets between the two tiers and L = height of lower tier. The safety factors were determined by using strength reduction factors. The factor of safety increased with an increase in the offset distance. Similar trends were observed for large-scale models.Practical ApplicationsJute geotextile reinforced fly ash models were analyzed using finite-element analysis. The results are relevant for the construction of fly ash wall reinforced with jute geotextile. The distance between the offsets was varied and a critical distance between the offsets was identified as 0.6L. The practical implication of the study is a reduced offset distance. The previous studies have identified a larger value of such distance. The current ratio for offset distance should be considered while designing the reinforced fly ash wall in tiered configuration. A change in position as well as value of tensile force acting on reinforcement was observed with the change in the distance between the offsets, thereby changing the location of failure plane. This should be taken in to account while designing the reinforcement for the wall.

Finite element analysis of compaction load to investigate the stress-deformation behavior of soil geosynthetic composite mass: A case study

When building Soil Geosynthetic Composite (SGC) walls, fill compaction is normally carried out by operating a compactor in a general direction parallel to the wall face. In other words, a moving point or area load is often used to apply a compaction load on a newly installed soil lift. Pham (2009) and Wu and Pham (2010) demonstrated that the compaction-induced stress (CIS) caused by multiple passes of a compactor moving toward or away from a section can be calculated by taking into account the compaction load applied directly above the section under consideration using a simplified stress path proposed by Duncan and Seed (1986). Additionally, by simulating the compaction, the CIS due to fill compaction may be correctly assessed. The CIS resulting from fill compaction can also be accurately assessed by simulating the compaction load, such as by applying a distribution load on top of each backfill layer or a distribution load at the top and bottom of each soil layer, or by applying various widths of strip load to the top of each backfill layer. The objective of this study was to validate the numerical simulation of the compaction load to stress deformation behavior of SGC mass under operating stress conditions. In order to conduct the numerical analysis, data from both a full-scale instrumented SGC mass based on large-scale soil geosynthetic composite (SGC) experiments and a 6 m-high SGC (Pham, 2009) were employed. This study will examine a few SGC behavior parameters, including reinforcement strains, lateral displacements, and reinforcement strains. The objective of the FE modeling is to demonstrate the effect, emphasize the significance of the compaction conditions to the stress-deformation behavior of SGC mass, and validate the findings from the field-scale experiments and proposed model by Pham (2009) and Wu and Pham (2010).

THE RIGHT-BANK TSIMLYANSK FORTRESS OF THE KHAZAR KAGANATE BASED ON THE 2006–2021 EXCAVATIONS

The right-bank Tsimlyansk settlement is a white-stone fortress doomed to destruction by the construction of the Tsimlyansk reservoir. The estimates of experts in bank transformation show that the fortress will disappear in the next 75 years, while the bank stabilization will take 200 years or longer. The paper presents the results of the 2006–2021 excavations along more than 56 m of the eastern fortress wall and in tower IV which were built from white limestone blocks laid on a base of shell rock and sandstone slabs. No wooden posts under the wall were found, as in the case of the southern corner of the fortress. The location of the tower corresponds to the 1743 plan by I. Satsyperov. Two options for its reconstruction are proposed. A unique feature of many blocks is the decoration in the shape of a straight and oblique grid. A number of building materials of Byzantine origin were found, including roof tiles and kalypters, as well as ceramic tiles. Another yurt dwelling (structure no. 50) typical for the fortress was uncovered. It is of fundamental importance that the dwelling adjoins the inner face of the fortress wall. Earlier, two more dwellings were found near the inner facade, but none has been found under the wall. This circumstance casts doubt on S.A. Pletneva’s hypothesis unsupported by M.I. Artamonov about the existence of an earlier settlement on the site of the fortress.