Failure Modes Of Walls Research Articles

Characterisation of timber joists-masonry connections in double-leaf cavity walls – Part 2: Mechanical model

The seismic assessment of the out-of-plane (OOP) behaviour of unreinforced masonry (URM) buildings is essential since the OOP is one of the primary collapse mechanisms in URM buildings. It is influenced by several parameters, including the poor connections between structural elements, a weakness highlighted by post-earthquake observations. The paper presents a mechanical model designed to predict the contributions of various resisting mechanisms to the strength capacity of timber-joist connections in masonry cavity walls. The research presented in this paper considers two different failure modes: joist-wall interface failure, and OOP rocking behaviour of the URM walls. Consequently, two mechanical models are introduced to examine these failure modes in timber-joist connections within masonry cavity walls. One model focuses on the joist-wall interface failure, adopting a Coulomb friction model for joist-sliding further extended to incorporate the arching effect. The other model investigates the OOP rocking failure mode of walls. The combined mechanical model has been validated against the outcomes of an earlier experimental campaign conducted by the authors. The considered model can accurately predict the peak capacity of the joist connection and successfully defines the contribution of each mechanism in terms of resistance at failure.

Prediction of Failure Modes of Steel Tube-Reinforced Concrete Shear Walls Using Blending Fusion Model Based on Generative Adversarial Networks Data Augmentation

The steel tube-reinforced concrete (STRC) shear wall plays an important role in the seismic design of high-rise building structures. Due to the synergistic collaboration between steel tubes and concrete, they effectively enhance the ductility and energy dissipation capacity of conventional shear walls. To identify vulnerable areas prone to brittle failure and optimize the design, it is essential to develop a rapid method for identifying the failure mode of STRC shear walls. In this study, a fast identification method of STCR shear wall failure modes based on a Blending fusion model with Generative Adversarial Network (GAN) augmented data is proposed. The GAN is employed to address the issue of inadequate experimental data by generating new samples. This method combines classification boosting (Catboost), Random Forest (RF), K-Nearest Neighbors (KNN), and Least Absolute Shrinkage and Selection Operator (LASSO) to establish the Blending-CRKL fusion model to improve the prediction accuracy of the failure mode of STRC shear walls. The results reveal a significant improvement in the prediction performance of KNN, Backpropagation Neural Network (BPNN), RF, Light Gradient Boosting Machine (LightGBM), Catboost, and Blending-CRKL models after augmenting the training set with GAN. On average, the accuracy increased by 13%, precision increased by 81%, recall increased by 48%, and F1 score increased by 67%. The proposed Blending-CRKL fusion model outperforms the tested KNN, BPNN, RF, LightGBM, and Catboost models, achieving an accuracy rate of 97% in predicting the failure mode of STRC shear walls. Additionally, the stability and robustness of the Blending-CRKL model were validated, while the important features and value ranges of different failure modes were analyzed. This study provides a reference for the rapid identification of the failure mode of STRC shear walls.

Experimental study on shear performance of improved high-performance polymer cement mortar–glass fiber reinforced plastic reinforced masonry wall

The improved high-performance polymer cement mortar (PCM) and glass fiber reinforced plastic (GFRP) system reinforcement was used in the research to strengthen and repair the masonry structure, so as to improve its bond stress, anchoring force, and integral performance without changing the original structure and further study the shear performance of masonry structure strengthened by the combination of the two. The optimum ratio of improved high-performance PCM was determined by analyzing the bend-press ratio of PCM test block. Improved high-performance PCM and GFRP were combined to strengthen the damaged masonry wall, and a five-piece masonry wall composed of “improved high-performance PCM+ with or without GFRP+ different original wall failure modes before reinforcement” was designed. Through diagonal loading shear test, the shear strength, vertical displacement, horizontal relative displacement, and failure models of masonry walls were obtained, and the effects of five different reinforcement methods and different materials on shear strength, stiffness, ductility, and failure modes of masonry walls were studied. The results show that compared with the unreinforced original wall, the shear strength of the masonry wall reinforced with the improved O4PCM is 43.5% higher, and its stiffness is also greatly improved, but the failure mode is still brittle failure; the shear strength of masonry walls strengthened by O4PCM and GFRP is 6.5% higher than that of masonry walls strengthened by O4PCM alone, and the stiffness is also increased. Its failure mode changes from brittle failure to ductile failure; with a failure mode of ductile failure, the shear strength of masonry walls strengthened by P4PCM and GFRP and that strengthened by P6PCM and GFRP are 4.8% and 12.7% higher than that strengthened by O4PCM and GFRP, respectively, and the stiffness is also increased compared with that strengthened by O4PCM and GFRP. After experimental comparison, it is the best scheme to strengthen masonry wall with improved P6PCM and GFRP.

Crushing of square honeycombs using disordered spring network model

The specific role of disorder in the cell-wall material of a two-dimensional cellular solid on its deformation and crushing failure under uni-axial compression was examined numerically and validated with existing experimental data. A random spring network model with nearest and next-nearest neighbour interactions was developed for the representative cellular architecture of staggered-square honeycomb. The springs were taken to be quasi-brittle in nature and to account for the disorder, spring failure properties were taken to be statistically distributed. The model is shown to be capable of reproducing the non-linear behaviour of honeycombs resulting from the damage accumulation and results are shown to be in agreement with experimental measurements in terms of stiffness, strength and energy absorption. Further, the role of disorder in the material properties on the types of failure modes was investigated. Increasing disorder in the spring failure threshold was shown to result in decrease in the peak strength but a more stable crushing response resulting from the increased separation between the two primary cell wall failure modes.

STUDY ON SHEAR BEARING CAPACITY OF COLD-FORMED STEEL COMPOSITE WALLS WITH LIGHTWEIGHT GYPSUM FILLINGS

In order to calculate the shear bearing capacity of cold-formed steel (CFS) composite walls with lightweight gypsum infillings, the full scale specimens including two unfilled walls and nine infilled walls were tested under reversed cyclic loading. The failure modes of the walls under horizontal loads were studied. The test results show that the failure modes of unfilled CFS walls are characterized by the screw connections between sheathings and CFS frames, thus causing the loss of stressed skin provided by sheathings. There are two possible failure modes of CFS walls with fillings. One is the compressive failure at the corner of gypsum fillings, and the other is the flexural failure of CFS studs. According to above-mentioned failure modes and limit equilibrium theory, a shear bearing capacity calculation model based on superposition method is proposed considering the contributions of sheathings and infill materials. Then the calculation equations of shear bearing capacity are also derived. The model can reflect the impact of screw connections strength, infill material strength and CFS frames strength on shear bearing capacity of the walls. The ratios of the theoretical calculation values to the test values are between 0.947 and 1.112, which demonstrates that the theoretical calculation values have a good agreement with tests values.

Performance of interlocking laterite soil block walls under static loading

Little is known about the performance of unreinforced interlocking block masonry walls made using CINVA-Ram blocks subjected to static compression loads. In a laboratory study, Pozzolanic cement (C), hydrated lime (L) and rice husk ash (RHA) were used to stabilize laterite soil with sandy clay loam texture. The stabilized blocks were used to make three types of walls. The results indicated that block compressive strength, water absorption and durability (1-min abrasion test) were within the recommended levels at the optimum stabilizer percentages. The wall failure modes were characterised by either diagonal cracking of individual blocks or spalling of block debris. The performance of interlocking block walls in load capacity can be divided into three parts: (1) slow closure of gaps, (2) rapid load uptake, and (3) wall failure. This paper has established that interlocking wall compressive strength can be increased while the vertical deflection reduced at the optimum stabiliser content.

Numerical analysis of geocell-reinforced retaining wall failure modes

Numerical analyses on the failure mode of geocell-reinforced retaining walls by the finite element strength reduction technique are reported. The effectiveness of the numerical model was validated by the centrifuge model test results. Parametric studies were conducted using the calibrated finite element procedure to investigate the effects of the apparent cohesion of geocell-reinforced soil, the friction between the wall base and the footing, the weak interlayer in the wall, and the layout of the two-tiered geocell-reinforced retaining wall on the failure surface and the factor of safety. The study results indicated that when the apparent cohesion was very large, or the friction between the wall and the footing was small, or there existed a weak interlayer in the wall, sliding failure was found to occur in geocell-reinforced retaining walls, similar to the failure mode of rigid retaining walls. Coulomb's wedge theory was suitable for the stability analysis of geocell-reinforced retaining wall in these conditions. However, in other conditions, which are more relevant in engineering applications, the failure mode of geocell-reinforced retaining walls was similar to that of slopes and the strength reduction technique for the stability analysis of slope may be suitable to analyze the stability of geocell-reinforced retaining walls.

Modelling the nonlinear behaviour of masonry walls strengthened with textile reinforced mortars

Textile Reinforced Mortars (TRMs) have found extensive attention for externally bonded reinforcement of masonry and historical structures. However, only few information is available regarding their mechanical properties and effectiveness in improving the seismic performance of strengthened structures. This paper presents an extensive numerical investigation on the effect of TRM composites on the nonlinear response and failure modes of masonry walls. The effect of boundary conditions and the TRM type on the performance of strengthened walls are critically discussed and presented. It is shown that the performance and failure mode of the walls can significantly change after strengthening, an important issue that should be considered at the design stage. Finally, the effect of TRM application on the nonlinear response of a large historical masonry façade in Macau is investigated and presented.

Flow-type landslide fragility of reinforced concrete framed buildings

Flow-type landslides may be triggered by several events such as heavy rainfalls, typically producing huge losses. Landslide risk may be rationally evaluated and mitigated with probabilistic approaches. In this paper, physical vulnerability of reinforced concrete buildings to flow-type landslides is assessed. Fragility analysis was carried out by assuming flow velocity as intensity measure, several damage states, and different mechanical models for beams, columns and masonry infill walls. Uncertainties in landslide impact loading, material properties, size and reinforcement of members, and capacity models were taken into account. Both earthquake-resistant and gravity-load designed framed buildings were assessed as being representatives of two building classes. Based on Monte Carlo simulation and a specific fragility analysis methodology, a set of landslide fragility curves were derived. Analysis results show that landslide fragility significantly depends on the presence and type of infill walls, which influences both out-of-plane and in-plane failure modes of walls themselves and RC frames. In addition, the proposed landslide fragility curves demonstrate that seismic design of RC buildings also plays a key role in the mitigation of their flow-type landslide fragility.

Seismic Response Evaluation of Ductile Reinforced Concrete Block Structural Walls. I: Experimental Results and Force-Based Design Parameters

The reported experimental study documents the performance of six fully grouted reinforced concrete block structural walls tested under quasistatic cyclic loading. The walls fall under the ductileshear walls and the special reinforced masonry walls seismic force resisting system (SFRS) classification of the Canadian and U.S. standards, respectively. The test matrix consisted of one rectangular, one flanged, and two slab-coupled walls, all with an overall aspect ratio of 1.4. In addition, two rectangular walls, representing the individual components of the slab-coupled wall systems, were tested to quantify the wall slab coupling effects. In addition to discussing the experimental results, the study also presents key force-based seismic design (FBSD) parameters, such as the wall lateral load capacity, plastic hinge length, wall failure modes, and displacement ductility capacities. Moreover, the effects of wall cross-sectional configuration and slab coupling on the cyclic response and deformation capabilities of the walls are discussed. In general, the yield and ultimate loads were found to be accurately predicted using the Canadian Standards Association (CSA) S304-14 and Masonry Standards Joint Committee (MSJC) formulations. The wall experimental displacement ductility values (calculated at 20% strength degradation) ranged between 5.4 and 7.6, whereas the idealized displacement ductility values at the same strength degradation level ranged between 3.4 and 5.4. The analysis results reported in the paper highlight the fact that walls designed and detailed within the same SFRS classification possess significantly different FBSD parameters. The results also indicate that slab coupling, although not recognized as a wall coupling mechanism in the current editions of the CSA and MSJC, can have significant influences on the seismic response of ductile/special reinforced masonry wall systems.

Axial load behaviour of pierced profiled composite walls with strength enhancement devices

This paper presents the results of experimental and theoretical investigations on a novel form of pierced double skin composite wall (DSCW) system consisting of two skins of profiled steel sheeting with an in-fill of concrete. Nineteen composite walls are tested to failure under axial loading. The test variables include: types of profiled steel sheeting, types of load transfer device, size/orientation of opening/holes, wall height and types of strength enhancement devices around holes. The effects of each of these variables on axial load–deformation response, axial strength, steel–sheet concrete interaction, failure modes (including concrete core cracking and steel sheet buckling) and stress–strain development are critically evaluated. Strengthening of hole boundaries is found to be essential in enhancing the axial strength of the walls. The performance of strength enhancement devices installed in the walls is found satisfactory based on axial strength–deformation characteristics and failure modes of walls. Theoretical model for the prediction of axial strength of both pierced and non-pierced composite walls is developed taking into consideration the reduction of concrete capacity due to profiling and buckling of steel sheeting. The performance of the model is validated through comparisons with experimental results.

Study on Failure Mode of Steel Fiber Reinforced High Strength Concrete Wall under Blasting Load

The dynamic response of the SFRHSC wall under blasting load is simulated and analyzed by establishing the 1/4 wall model with finite element explicit dynamic analysis software ANSYS/ls-dyna. Considering the damage and strain rate effect, the J-H-C model is used as material model, and model parameters are calculated by using the test of literature data. The explosion loaded by CONWEP model and *LOAD_BLAST keyword. Different failure modes of wall under different scaled distances are analyzed, the results show that shear failure will occur when the scaled distance is small, flexure failure will happen when the scaled distance is large, in addition, comparing with normal reinforced concrete, the displacement in the center of the SFRHSC wall is smaller under the same condition, which embodied that the high tensile strength and compressive toughness of SFRHSC are significantly enhanced the anti-explosion ability of the wall. The research results of this article can provide reference for the design of SFRHSC fender wall.

Loading Height on Reinforced Brick Masonry Wall’s Failure Mode and Seismic Performance with Finite Element Analysis Method

Masonry structure, the number of large, wide area distribution, and earthquake damage survey, masonry structure severely damaged. In this paper, using the finite element tool ABAQUS, combined with an equivalent volume element simulation technology, the establishment of spatial finite element model to study the loading height of the brick wall failure modes and effects of seismic performance issues in depth analysis of its constant vertical pressure, different loading height seismic performance and failure modes under. The results show that: the greater the load height, the wall more prone to bending failure, otherwise prone to shear failure; loading height bigger, better ductility of the wall, the ultimate bearing capacity is smaller.

Numerical modeling on brittle failure of coal wall in longwall face—a case study

In China, as the shearer cutting height increases in longwall face, serious coal wall failure and spallings occur often, especially for brittle coal seam, which leads to large block spallings, equipment damage, and casualties. In this paper, 2D finite difference models are constructed, aiming to exam the brittle failure of coal wall during longwall mining in Majialiang coal mine, Shuozhou, China. The strain-softening constitutive model is used to reveal the brittle failure characteristics of the coal wall. A numerical algorithm is developed to simulate the longwall goaf compaction process, and obtain the proper mining-induced stress around the longwall face. Based on extensive field surveys, three numerical models, i.e., intact coal wall, coal wall including vertical discontinuities and criss-cross discontinuities, are presented for investigating the brittle failure mode and spalling mechanism of the coal wall. The numerical results show that both coal wall failure modes and the failure (spalling) depths are in good agreement with the field observations. The simulations reveal that the sizes of the spalling blocks are closely related to the failure mode. For intact coal wall or coal wall including large space vertical discontinuities, occurrences of the large block spallings are favorable. For coal wall including small space vertical discontinuities and criss-cross discontinuities, small segment spallings play a dominant role. In light of this, analyses are conducted to investigate the effects of the face stoppage time and face guard on the failure mode and spallings of the coal wall. The result of this study indicates that the mining operation should accelerate and the length and pressure of the face guard should increase in this longwall face.

In-plane behavior of perforated brick masonry walls

This paper reports the results of experimental and theoretical research conducted on perforated brick masonry walls under in-plane loading. The walls’ structural behavior depends strongly on their specific features, e.g. geometry, mechanical properties of the masonry material, brick arrangement and loading conditions. The experimental program was designed to study the incidence of brick arrangement in the spandrels and piers, and of the acting vertical load on the failure mode and load-bearing capacity of the walls. Six specimens of brick masonry wall with a central opening were submitted to a constant vertical load and a monotonic horizontal force that was gradually increased until the kinematic mechanism condition was reached. The object of the theoretical research was to develop a simplified analytical model for describing the kinematic mechanism of the walls. The results of the experiments indicate that brick arrangement strongly influences the failure mode and load-bearing capacity of the walls. Proper a priori assessment of the failure mode of walls becomes fundamental to an accurate evaluation of their load-bearing capacity using the proposed model.

Shaking table study and modelling of seismic behaviour of confined AAC masonry buildings

The response of autoclaved aerated concrete confined masonry buildings to seismic ground motion has been studied. Three 1:4 scale models of residential buildings with the same distribution of walls in plan but different types of floors and number of stories have been tested on a uni-directional shaking table. Lightweight prefabricated slabs have been installed in the case of the three-storey model M1, whereas reinforced concrete slabs have been constructed in the case of three-storey model M2 and four-storey model M3. Model M1 was subjected to seismic excitation along the axis of symmetry, whereas models M2 and M3 were tested orthogonal to it. Typical storey mechanism, characterised by diagonal shear failure mode of walls in the ground floor in the direction of excitation has been observed in all cases. Taking into consideration the observed behaviour, a numerical model with concentrated masses and storey hysteretic rules has been used to simulate the observed behaviour. Storey resistance curves calculated by a push-over method and hysteretic rules, which take into account damage and energy based stiffness degradation hysteretic rules, have been used to model the non-linear behaviour of the structure. Good agreement between the experimentally observed and calculated non-linear behaviour has been obtained.

BEHAVIOR OF SHEAR WALLS UNDER AXIAL LOAD AND CYCLIC LOAD

Reinforced concrete walls are often introduced into multistory buildings toresist lateral forces which can be exists due to winds or earthquakes. Inthe present study, six models I–section shear wall models were tested undercombined action of a constant axial load and reversal horizontal increasedloading until failure. The study has investigated the effects of someparameters such as, the height – to – width ratio, the compressive strengthof concrete, and the variation of main flexure reinforcement ratio on thebehavior of high - strength concrete shear walls. The obtained resultsfrom the tests have helped to identify the causes of wall failure modes. Thetest results included the determination of ultimate load, deflection, mode offailure, crack pattern, ductility, stiffness, and energy absorption.

Damaged masonry walls in two-way bending retrofitted with vertical FRP strips

Unreinforced masonry (hereafter termed ‘masonry’) structures comprise a significant proportion of the building stock in many countries worldwide, however their walls do not behave well under out-of-plane loading, such as that experienced during seismic events. Consequently, many existing masonry structures require some form of retrofit to comply with existing codes. As part of ongoing research at The University of Adelaide on the out-of-plane bending behaviour of masonry walls, eight full-scale walls (with window openings) were tested under reversed-cyclic loading. Four of the severely damaged walls were subsequently retrofitted using externally bonded (EB) (three walls) and near-surface mounted (NSM) (one wall) fibre-reinforced polymer (FRP) strips and tested again to quantify the increase in strength and ductility relative to the original capacities. A debonding mechanism not yet quantified for retrofitted masonry walls was observed and identified as displacement induced (DI) debonding. It is a result of a differential out-of-plane displacement at either side of a crack in the wall. NSM strips are more susceptible due to their orientation. This paper presents the results of the wall tests along with detailed accounts of the wall failure modes.