Face Of Wall Research Articles

Effect of Various Rainfall Conditions on the Roadside Stabilisation of Slopes in Gippsland

A distinctive slope stabilisation method that integrates two well-developed methods for slope stabilisation is analysed in this paper. The slope stabilisation method utilises embedded piles and geogrid-reinforced retaining walls with gabion basket wall facing. To study the effect of this integrated slope stabilisation method on the stability of the slope under the negative impacts of rainfall, a three-dimensional finite element model with fluid–solid coupling is adopted to indicate the rainfall infiltration process and investigate the corresponding slope responses. The shear strength reduction method is applied after fluid–solid coupling analysis to investigate the impact of various rainfall intensities and rainfall patterns on the stability of slopes with different configurations. The results from the comparison of slope responses among various configurations indicate that under the highest rainfall intensity, the integrated method improves the stability of the slope up to 41.2% and restrains the displacement increment of the road edge to a maximum of 12.5 mm. The most critical rainfall pattern for the stability of the slope has also been recognised in terms of the factor of safety and the variation in the negative pore-water pressure of the slope. The numerical results indicate that the back-loaded rainfall pattern always yields the lowest factor of safety and induces the highest loss of matric suction, which can be 23 kPa at the toe of the slope. Moreover, a comparison between two construction scenarios under various rainfall intensities was also conducted, which demonstrates that the reinforced filled slope configuration is preferable when the site conditions permit.

Investigation of the effect of modular construction details on the lateral behaviour of cold-formed steel framed shear walls

This paper investigates the effect of modular construction details on laterally-loaded cold-formed steel (CFS) framed shear walls sheathed with wood- and cement-based panels by means of finite-element (FE) analyses. Shell FE-based models have been developed in ABAQUS with the aim of accurately capturing the behaviour, strength and stiffness as well as the corresponding failure modes of CFS framed shear walls subjected to monotonic lateral load (i.e., wind). User-defined element subroutines were adopted for precise modelling of sheathing-to-CFS screws shear behaviour. The proposed modelling protocol is validated using experimental test results, where an acceptable concordance (4% difference) has been achieved. Subsequently, the effect of modular construction details, which go beyond the scope of the current lateral design provisions (AISI S400), on the lateral behaviour of CFS framed shear walls is assessed. In particular, this paper investigates the impact of: (i) floor and ceiling ledger beams on the interior face of the shear wall, (ii) sheathing boards having different sizes from the overall shear wall and thus the presence of both vertical and horizontal seams, (iii) cement particle boards at the bottom stripe of the shear wall and (iv) different screw spacing in the top and bottom stripes from the middle part of the shear wall. The key parameters, which have most affected the lateral behaviour, were identified, and based on that, rules have been established for optimizing the screws pattern and sheathings layout efficacy in the above-described lateral load resisting system. The obtained results shed light on the capability of the developed modelling protocol to be used as a virtual test bench, particularly in offsite mass production and manufacture (DfMA), for the development of a new CFS framed wall system for lateral stability of lightweight modular houses.

Two Iron Age duns in western Scotland

This report discusses the excavation of two stone-walled duns situated in North Knapdale, Argyll and Bute, led by Kilmartin Museum. Substantial areas of both sites were excavated, providing a good stratigraphic record of the development of the structures. Both sites proved to be multiphase, and six radiocarbon dates established a fairly restricted period of occupation for both in the last centuries of the 1st millennium BC and the first centuries AD. These dates are important contributions to an ongoing debate on the chronology of duns and forts in Argyll as there are so few reliable dates for this class of monument. At Barnluasgan an oval structure enclosing a craggy knoll was replaced by a smaller circular one. At Balure, in contrast, a primary circular structure had a series of successive enclosures added. Both circular structures had internal post holes and hearths, suggesting they were roofed ‘dun-houses’. No intramural features were seen, but median wall faces were present. Artefacts were sparse, as is usual on sites of this period, but included an unusual decorated rotary quern, and rare glass toggles. There are detailed reports on the artefacts and on the palaeobotanical remains. The landscape context of the sites is explored, and a discussion places the sites in this context and in relation to debates on classification of stone-walled structures in Atlantic Scotland.

Deterministic and probabilistic prediction of maximum wall facing displacement of geosynthetic-reinforced soil segmental walls using multivariate adaptive regression splines

A surrogate model-based response surface method is proposed to predict the maximum wall facing displacement of geosynthetic-reinforced soil (GRS) segmental walls using the multivariate adaptive regression splines (MARS). The synthetic datasets are generated using the Latin hypercube sampling (LHS) technique for both training and testing purposes. For each input dataset, the maximum wall facing displacement is evaluated using the finite difference software FLAC. An expression for the maximum wall facing displacement is proposed in terms of basis functions (piecewise linear). The performance of the proposed model is assessed in terms of the ratio of predicted and simulated maximum wall facing displacement, and the results show that the performance is satisfactory. Moreover, the study identifies that the effect of soil friction angle is most apparent in predicting the maximum wall facing displacement. The efficiency of the proposed model is compared with other soft computing techniques, and the result indicates that the proposed model gives minimum error. Further, a probabilistic study is performed in terms of the normalized maximum wall facing displacement. The results show that the probabilistic prediction of the maximum wall facing displacement using the proposed model is within the range of specified limit.

Turbulent flow simulations of the common research model on Cartesian grids using recursive fitting approach

In this study, we propose a new method that uses the recursive fitting method and wall function for the three-dimensional turbulent flow simulation. The recursive fitting method based on the Cartesian grid method is employed for the automatic generation around two- and three-dimensional geometries. The grid approximately represents the concave and convex features, i.e., a wing–fuselage juncture and wing trailing edges. The wall boundary conditions can be imposed on the wall faces; thus, the conservation laws are strictly satisfied. Meanwhile, using the wall function allows turbulent boundary layers to be accurately reproduced. The turbulent flow simulation using the wall function is straightforward because the flow variables at the first cell centroid are employed for friction velocity estimation. However, the distance between the body surface and the first cell centroid varies since cells with different shapes are generated. Therefore, the simulation using the proposed method is validated through turbulent flow simulations in two dimensions. The results show the accurate predictions of the turbulent boundary layers. To investigate the capacity of the proposed method, three-dimensional simulation around aircraft at a transonic cruise condition is conducted. The automatically generated grids by the proposed method approximately represent the geometric features. The results of flow simulation show that the surface pressure and skin friction coefficient distributions agree with those of the reference simulation on a conventional body-fitted grid. Further, predicted pressure and viscous drag coefficients are reasonable compared with those of the reference simulation.

Research of a new hot-rolled connector connection to composite walls

The composite members in steel residential buildings often possess small sections and have high restrictions on the indoor space extrusion of structural components, and then traditional diaphragm type and internal or exterior stiffener connections are hardly applied. A new hot-rolled connector connection was proposed, which used the flange-to-web arch transition of hot-rolled steel beams as the intermediate connector. The smooth section transition of the connector at the column face junction can reduce the stress concentrations and premature fracture potentials of connections between H-shaped beams and small-size composite walls or CFST columns in steel residential buildings. Four hot-rolled connector connections with different connector designs and beam sizes were tested under cyclic loads, and the seismic performances and working mechanisms were investigated. Refined finite element simulations were performed to indicate the load transfer path and load sharing mode in the connection. Results indicated that the proposed connection displayed plump hysteretic relations and satisfactory energy dissipation ability. The strengthened connectors succeeded in inducing the high plasticity away from the wall or column face. The bottom beam flange to connector butt weld was prone to fracture. The HTC connection with a long HTC connecting beam and the two bolt-row construction as the web connection was suggested.

Numerical response prediction of full-scale concrete walls subjected to simulated in-plane seismic loading

Robust numerical predictions of the response of concrete shear walls to in-plane earthquake demands are important for the performance evaluation of structures that rely on such elements for their lateral strength and stability. Numerical modeling techniques must balance complexity and accuracy against efficiency and ease of interpretation. Correctly representing in-plane cracking and spalling can also be useful for the assessment of structural and nonstructural systems attached to the walls’ surface. A numerical model capable of representing coupled shear-flexure interaction is selected in this study and validated against tests conducted on three full-scale reinforced concrete walls with varying geometric characteristics. Results are compared at key performance states commonly used in performance-based seismic design to quantify damage. Focus is given to the distribution of the predicted crack pattern to provide insight on the likelihood of the impact of concrete damage on the performance of attachments to the wall face (structural and nonstructural connections). This validation study demonstrates the reasonable predictive capabilities of the selected model in terms of global and local responses. Despite the simplifications of the model, e.g., lack of specific modeling of reinforcement debonding and out-of-plane deformations, an overall reasonable estimation of cracking and damage distribution is observed. This study enhances efforts to provide a more reliable seismic design and performance assessment of reinforced concrete buildings.

Performance of helical soil-nailed walls under bridge abutment

In the current study, the performance of helical soil-nailed walls (HSNWs) was evaluated under bridge abutment using reduced-scale model tests. For this purpose, sixteen wall models were constructed with different lengths, patterns and inclinations of the helical nails and then were loaded to failure using the strip footing. Findings indicated that 15° can be introduced as the optimal inclination for installing helical nails in walls under bridge abutments to achieve the maximum bearing capacity and minimum lateral wall displacements. It was found that although using longer nails and installing them in a square pattern and optimal angle reduced the penetration depth of the slip surface, but caused more portion of the bridge footing pressure to be converted to connection load and, consequently, bending in the wall facing. Moreover, the role of the lower rows of nails in the stability of HSNWs was found to be more prominent than the upper rows. Also, it was concluded that the method proposed by FHWA [1] to calculate the connection load could be used as an upper bound in helical soil-nailed walls under bridge abutment.

Measurement prototype for fast estimation of building wall thermal resistance under controlled and natural environmental conditions

Most of the methods for in situ measurement of the thermal resistance of building walls implement passive approaches requiring long measurement times and specific environmental conditions. In the literature, different active approaches have been studied but they remain limited in terms of applications and do not systematically lead to short identification times. This article that follows a previous numerical benchmark study presents a new measurement prototype using a lamp box which heats up one of the surfaces (typically the interior surface) of the wall to be characterized. The use of an aluminum plate placed in contact with the wall face subjected to thermal excitation enables the homogenization of the heat flux transmitted to the wall. Three inverse procedures are implemented to estimate the thermal resistance of the studied wall. The originality of this work comes from an exhaustive measurement campaign. On the one hand, four types of wall among the most common in France, i.e. Internal Insulation Wall, External Insulation Wall and Wood Frame Wall specially built for this study and a Single Concrete Wall located in a real building, were investigated. On the other hand, the use of different climatic chambers made it possible to generate many different environmental conditions (constant, variable and natural). The results highlight the possibilities offered by this in situ experimental device for estimating in a few hours (6 to 10 h) the thermal resistance of the wall studied or of its first layers, as well as the limits depending on the type of wall and the environmental conditions. Some operational recommendations are also provided: avoiding thermal bridges, solar protection in case of strong sunlight on the exterior side of the wall and location of the device on the exterior side in the case of the External Insulation Wall.

The Distinctively Basque Stone Shelters of California’s White Mountains

Basque and French shepherds in California’s White Mountains built dry stone shelters that persist today. Despite French names carved on logs associated with a few of these structures, the typical pattern for these shelters is Basque: they closely resemble the cabañas pastoriles (shepherd’s huts) of Bizkaia. A square floor plan with walls about one meter high enclose a single chamber. The stone work is carefully laid to make one wall face. A narrow doorway, often in a corner, faces downhill in any direction except west and can be flanked by low stone “spurs”. A fireplace is usually built into the south wall. Boulders too large to move are usually in the western wall or northwest corner. Metal, glass, wood, bone or leather artifacts are present. Typically Basque arborglyphs (carvings in aspen trees) are found nearby at lower elevations. It is unclear whether the White Mountains shelters originally had roofs.

Bacterial decay in waterlogged archaeological compression wood varies with severity of compression wood

Abstract Bacterial decay in compression wood (CW) tracheids of waterlogged archaeological wood (WAW) was investigated using light microscopy, confocal laser scanning microscopy, transmission electron microscopy (TEM), and TEM immunogold labeling. Erosion bacteria were identified as the main degraders, and the extent of cell wall degradation differed depending on the severity of CW tracheids (mild vs. severe). Mild CW tracheids showed preferential decay in the inner S2 layer, with the locally degraded and/or fragmented S3 layer remaining. In contrast, severe CW tracheids revealed gradual degradation of the cell wall from the erosion progressing from exposed faces of the cell wall as decay progressed. The overall decay was more extensive in mild than in severe CW tracheids, and degradation of the highly lignified outer S2 layer (S2L) was only detected in mild CW tracheids. TEM immunogold labeling of 1,4-β-galactan, homogalacturonan (HG), heteroxylan, and heteromannan epitopes showed that there was no preferential degradation of pectins and hemicelluloses by action of diffusible enzymes and/or agents through the un-decayed cell wall during bacterial decay, in both mild and severe CW tracheids. Inter-CW tracheid bordered pit membranes showed higher decay resistance than CW tracheid walls. Degradation of HG and heteromannan epitopes was suppressed in pit membranes.

Experimental and Numerical Evaluation of Mechanically Stabilized Earth Wall with Deformed Steel Bars Embedded in Tire Shred-Sand Mixture

This article presents the experimental and numerical analysis behavior on Mechanically Stabilized Earth Wall (MSE) under applied overburden load performed on the 1.5 m high, 0.9 m width, and 1.2 m length reinforced with deformed steel bars embedded in sand alone and tires shred-sand mixture. The study investigates how deformed bars, strength, and geometry affect the failure mechanism. The top of the wall was laden with additional overburden weight at various stages to explore the pre-failure wall behavior. The horizontal displacements were measured using potentiometers of the wall face and by potentiometers placed at the top of the loading plate. The results of the observations were compared to the analysis results derived from a numerical model created using the Plaxis 3D software. Numerical modeling was also applied to assess the behavior of MSE wall (3D model) on the failure mechanism of the walls. The parameters for the numerical models were derived from independent tests results, which were compared with the experimental observations. A good level of agreement with measurements was confirmed for the 3D model with the experimental data. From the results, it was deduced that at 30 kPa and 40 kPa, the tire shred-sand mixture with reinforcement gave a 36% and 58% reduction in face deflection compared to sand with reinforcement. The difference between numerical and experimental values ranges from 12% to 15%.

Experimental study on the mechanical behavior of shored mechanically stabilized earth walls for widening existing reinforced embankments

Shored mechanically stabilized earth (SMSE) walls have been increasingly applied in embankment widening projects because of their good mechanical performance, simple construction, low cost, and low site requirements. In this paper, several large-scale model tests were conducted to explore the mechanical behavior of the composite structures with different connection forms and relative densities, and the wall deformation, earth pressure, reinforcement strain, potential failure surface and the effects of the connection forms behind SMSE walls were also analyzed. The results show that the deformation of SMSE walls is mainly concentrated on the upper middle part, showing a “bulging” failure trend. The deformation of the SMSE walls can be effectively controlled by improving the relative density and adopting a “sandwich” connection behind the walls. The horizontal earth pressure against the SMSE wall facing shows a “K”-shaped distribution, and the vertical earth pressure is large in the upper part and small in the lower part. The potential failure surface originated at the junction of the old and new retaining walls, forming a “double-line” failure surface. For a “sandwich” connection, the failure surface moves forward and occurs where the primary and secondary reinforcements overlap, and this connection form is recommended in engineering practice.

Design of reinforced cohesive soil walls accounting for wall facing contribution to stability

Where granular materials are not easily available, local cohesive soils are increasingly employed in geosynthetic reinforced soil walls as a cheap and sustainable option. Conventional design methods do not yet account for the beneficial effect of cohesion in reducing the amount of required reinforcement. Similarly, the contribution of the face to stability is rarely accounted for, despite plenty of experimental evidence in its favour. In this paper, a semi-analytical method based on limit analysis is developed for the design of reinforced soil walls in frictional–cohesive backfills accounting for the wall contribution. A parametric analysis was conducted to evaluate the effect of soil cohesion and friction angle, facing batter, block width, location of the reaction force acting on the face, facing–backfill interface friction, facing–foundation interface friction and reinforcement length. Dimensionless design charts providing the required amount of reinforcement for lengths recommended in design standards are provided for both uniform and linearly increasing reinforcement distributions. It emerges that accounting for the presence of cohesion and the facing element can lead to significant savings in the overall level of reinforcement, and that tension cracks can be particularly detrimental to wall stability for highly cohesive soils so they cannot be overlooked in the design.

Development of a method for calculating the transmission‐line constants of cables installed in a rectangular tunnel

AbstractAccurately calculating the transmission‐line constants of underground cables is important for various types of power system simulations such as electromagnetic transient, power flow, and transient stability simulations. The transmission line constants of cables installed in a tunnel must be calculated taking the skin and proximity effects into account, since the cables are spaced closely to each other and also to a wall face of the tunnel. However, the conventional method, which is capable of considering the skin and proximity effects, has been restricted to circular cross‐section conductors such as cables and a circular tunnel. Therefore, the method cannot handle a tunnel with a rectangular cross section. In this paper, a method for calculating the transmission‐line constants of a conductor system in which both circular and rectangular cross‐section conductors present in the same space is proposed. Then, the walls of a rectangular tunnel are represented by eight rectangular conductors, and cables represented by circular conductors are placed inside the eight rectangular conductors. In this paper, the proposed method is verified by experiments using a conductor system in which three circular conductors are arranged in a rectangular conductor. Calculated results obtained by the proposed method agree well with the measured results.

Investigation of the Usability of Nevşehir (Kavak) Region Cherry Colored Ignimbrite in Wall Facing

Farklı renklerdeki doğal taşların dekoratif görüntüsü ve bazı fiziksel özelliklerinden dolayı son yıllarda inşaat sektöründe kullanımı gittikçe artmaktadır. Gelişen taş işleme teknolojisiyle birlikte doğal taşlar özellikle duvar kaplama malzemesi kullanılmaktadır. Bu doğal taşlar arasında en yaygın kullanılanlardan birisi de ignimbiritlerdir. Bu çalışmada Nevşehir (Kavak) yöresinden temin edilen vişne renkli ignimbirit taşının teknik özellikleri araştırılmıştır. İgnimbirit örnekleri üzerinde TS EN 1469 ve TS 699 standartlarında önerilen fiziksel özelliklerinden porozitesi, yoğunluğu ve farklı etkiler altındaki su emme özellikleri incelenmiştir. Mekanik özelliklerinden ise basınç, eğilme ve dolaylı çekme dayanımları, nokta yükleme ve saplama deliğinde kırılma yükü özellikleri belirlenmiştir. Araştırma sonucunda elde edilen verilere göre ignimbiritlerin fiziksel özellikleri bakımından gözenekli bir yapıya sahip olup su emme kapasitesinin yüksek olduğu belirlenmiştir. Mekanik özeliklerinden eğilme dayanımı 11,9 MPa iken ortalama kırılma yükü 1180 N bulunmuştur. Bu özelikler TS EN 1469’da belirtilen doğal taş kaplama plâkalarında aranan ölçütleri karşılayamadığı ve bu nedenle inşaat sektöründe kaplama taşı olarak kullanımının uygun olmadığı değerlendirilmiştir.

Natural disaster mitigation using advanced ferrocement – Future research directions for improved building resilience

Natural disaster mitigation encompasses a wide range of activities which are required to avert the occurrence of natural disasters and is a major goal of the Sendai Framework applicable to all exposed territories worldwide. With respect to earthquakes and hurricanes, the structural retrofitting of buildings which were designed before the availability of seismic codes of practice, or the enforcement of existing codes, can be an effective form of mitigation. Advanced Ferrocement (AF), which is ferrocement based on Lamination Theory (LT), encompasses the use of mesh angle, layer-by-layer mesh layup, possibly with non-metallic mesh, and/or non-standard mortars, for the design and construction of structural components. As a pilot study, a set of core research questions and nine research directions or study areas are presented for investigating the use of AF for retrofitting existing buildings, in the context of earthquake and hurricane resilience. This is also useful for deriving new structural components for new buildings,. The experimental results of the pilot study are that when ferrocement overlays were applied to the faces of concrete masonry-infilled walls of steel frames, the lateral yield strength and displacement at yield increased by factors of 1.50 and 2.30, respectively. For the tested ferrocement shear panels of channel-shaped cross-section, the lateral maximum strength-to-weight ratio was 3.37 times higher than that for an alternative reinforced concrete masonry minimum cost solution. For the tested AF one-way spanning roof panel, the wind load capacity had a strength-to-weight ratio 10.78 times higher compared with the present minimum cost metal sheet-and-purlins solution. LT suggests that the performance of the infilled-frame retrofit, and the ferrocement wall panel, can be increased by aligning the mesh in the principal stress directions, etc. The research directions and preliminary findings presented can serve as the basis for an extensive research effort regarding AF as the application of LT to mesh-reinforced cementitious composite structural building components.

Seismic response of geogrid-reinforced fiber-cement soil walls using shaking table tests

Improving the characteristics of local low-strength soils at the construction site is one of the appropriate approaches to employ the soils as a backfill of geogrid-reinforced soil (GRS) walls. In this study, the fiber-cement-treated sand–silt mixture was used as the backfill of walls. The post-earthquake performance of the walls was evaluated by applying the sinusoidal waves on 1 m high reduced-scale physical models and conducting a series of 1g shaking table tests. A comparison of the wall models constructed with treated and untreated backfill indicated the advantages of geogrid-reinforced fiber-cement-treated soil walls subjected to strong ground motion. The results revealed the better behavior of the wall models backfilled with treated soil mixtures under dynamic loading. Such improved performance was more evident in (i) deformation responses, including the lateral displacement of wall facing, deformation mode, failure surfaces, and settlement of backfill surface and (ii) acceleration response in different locations, including facing, reinforced, and retained zones of walls.

Laterally-loaded pile-MSE wall system performance under different design configurations

The need for constructing a shallow or deep foundation (e.g. piles) in a mechanically stabilized earth (MSE) wall for superstructure support has increased. However, the performance of laterally loaded piles within the MSE wall and their interaction with soil and reinforcement are not fully understood. Limited full-scale tests and numerical studies have been conducted to evaluate the behavior of laterally-loaded piles within MSE walls. In this study, thirteen reduced-scale model tests were performed to investigate the effects of changing the wall configuration (wall height, and reinforcement spacing and length) and the pile location on the performance of the pile-MSE wall system under static lateral loads. This experimental study found that the piles in high walls could develop larger maximum compressive and tensile strains. Low walls resulted in larger wall facing deflections and maximum tensile strains in the geogrid reinforcement. Small reinforcement spacing and long reinforcement length resulted in higher pile lateral load capacities, smaller wall facing deflections, and smaller reinforcement tensile strains. The pile offset from the back of the wall facing is a critical factor that affected the pile capacity, the wall facing deflection, the reinforcement tensile strain, and the lateral earth pressure distribution behind the wall facing.

Effect of internal drainage on deformation behavior of GRS wall during rainfall

Global warming-induced changes in the pattern and amount of precipitation are important from the viewpoint of long-term stability of geo-structures. In this paper, the effectiveness of in-plane drainage provided by permeable geosynthetic reinforcement was evaluated as a means to relieve the rainfall infiltration effect on GRS walls backfilled with marginal soil. A series of laboratory tests were performed using a reduced-scale model geosynthetic reinforced soil (GRS) wall (constructed with due consideration of the similitude law) with different rainfall characteristics and backfill soils. Layers of nonwoven geotextiles were used as reinforcement as well as in-plane drainage media. The results showed that the inclusion of internal drainage facilitated the dissipation of pore water pressure, thereby reducing the wall facing displacement. The discharge water volume and volumetric water content data measured in the reinforced soil zone supported the observation. The degree to which the internal drainage improves the deformation behavior of the GRS wall during rainfall was found to depend on the rainfall characteristics and the backfill soil type. Practical implications of the findings are discussed in detail.