In-plane Seismic Performance Research Articles

Experimental study on the in-plane seismic performance of fully grouted interlocking block walls

The construction process of conventional masonry structures is complicated, which leads to time-consuming and skilled labor dependence. Dry-stacked interlocking system (DSIM) represents an innovative approach, with the aim of improving construction efficiency and reducing manpower needs. Interlocking masonry structures reinforced by grouting and reinforcement have great advantages because they can be applied to different intensity areas by using suitable grouting strength and reinforcement ratio. In this paper, the interlocking block was developed and mechanical properties of solid waste regeneration interlocking blocks were studied, including compressive test of a block unit, compressive test of grouted and ungrouted prisms, and shear test of grouted prisms. Subsequently, four grouted interlocking walls were designed by the orthogonal experimental method, considering three influencing parameters (aspect ratio, vertical load, as well as grouting strength and reinforcement layout). The in-plane cyclic loading was performed to evaluate the seismic behavior of grouted interlocking walls. Finally, the behavior of four fully grouted interlocking walls was analyzed in terms of load-displacement response, failure modes, stiffness, displacement ductility, energy dissipation, and rebars strain. The failure observation and deformation analysis indicate that the grouted interlocking walls exhibited flexural failure. The grouted interlocking walls had outstanding integrity and bearing capacity benefiting from the combination resistance of grouting concrete, rebars, and interlocking block.

Influence of Confining Element Stiffness on the In-Plane Seismic Performance of Confined Masonry Walls.

Confined masonry (CM) construction is being increasingly adopted for its cost-effectiveness and simplicity, particularly in seismic zones. Despite its known benefits, limited research exists on how the stiffness of confining elements influences the in-plane behavior of CM. This study conducted a comprehensive parametric analysis using experimentally validated numerical models of single-wythe, squat CM wall panels under quasi-static reverse cyclic loading. Various cross-sections and reinforcement ratios were examined to assess the impact of the confining element stiffness on the deformation response, the cracking mechanism, and the hysteretic behavior. The key findings included the observation of symmetrical hysteresis in experimental CM panels under cyclic loading, with a peak lateral strength of 114.3 kN and 108.5 kN in push-and-pull load cycles against 1.7% and 1.3% drift indexes, respectively. A finite element (FE) model was developed based on a simplified micro-modeling approach, demonstrating a maximum discrepancy of 2.6% in the peak lateral load strength and 5.4% in the initial stiffness compared to the experimental results. The parametric study revealed significant improvements in the initial stiffness and seismic strength with increased depth and reinforcement in the confining elements. For instance, a 35% increase in the lateral strength was observed when the depth of the confining columns was augmented from 150 mm to 300 mm. Similarly, increasing the steel reinforcement percentage from 0.17% to 0.78% resulted in a 16.5% enhancement in the seismic strength. These findings highlight the critical role of the stiffness of confining elements in enhancing the seismic performance of CM walls. This study provides valuable design insights for optimizing CM construction in seismic-prone areas, particularly regarding the effects of confining element dimensions and reinforcement ratios on the structural resilience.

In-plane seismic performance of historical masonry walls with various brick bond patterns using micro-modeling approach

In-plane seismic performance of historical masonry walls with various brick bond patterns using micro-modeling approach

In-plane seismic performance of precast concrete hollow-core slab panels for basement walls

In building structures, exterior basement walls should resist the soil pressure type earthquake load transmitted by the ground. Thus, the structural performance of the exterior basement walls is affected by in-plane seismic performance as well as out-of-plane load resistance. In the present study, for better constructability and cost-effectiveness of the exterior basement walls, conventional reinforced concrete walls were replaced with precast hollow core slab (HCS) panels. To investigate the in-plane earthquake load resistance of HCS for exterior basement walls, cyclic lateral loading test and numerical analysis were performed on four HCS panels with in-plane double curvature. The test and analysis results showed that the structural behavior of the HCS panels was significantly affected by the panel layout. In the test specimens using a single panel, flexural compression failure occurred at the bottom of the panel, and shear friction damage occurred at the upper and lower parts of the panel. In the test specimens using double panels, failure mode was governed by direct shear. The load-carrying capacity of the test specimens using double panels was greater than two times that of the test specimens using a single panel, because the load transfer changed from flexure into direct shear in the wall specimens using double panels. Further, to use HCS panels for exterior basement walls, a design method for prediction of in-plane seismic performance and yield displacement of HCS panels was proposed.

Experimental database and analysis of in-plane seismic behaviour of double steel-plate composite walls for wind power tower

A double-steel-plate composite wall (DSCW) is composed of two steel plates, infilled concrete, and connectors. Because of their superior mechanical performance, DSCWs have been widely used in engineering, especially in the field of wind power tower. However, only a few studies have been conducted on the in-plane seismic performance of DSCWs. This study focused on the in-plane seismic performance of DSCWs, and a dataset of the in-plane flexural and shear behaviours of DSCWs including over 200 specimens from more than 30 studies was built. First, various structural configurations and mechanical response parameters were adjusted to the same standard. The same parameters studied by different scholars were extracted and analysed to obtain the general rules of the influence of these parameters on the hysteresis performance of DSCWs (forward analysis), such as the distance-to-thickness ratio, axial load ratio, shear span ratio, connector type, steel plate thickness, material strength, and partition number. Second, a backward analysis using the entire database was conducted on the factors influencing different mechanical response parameters, including the failure modes, yield displacement angle, ultimate displacement angle, ductility, and energy dissipation capacity. Finally, the accuracy of the shear capacity equations in the different codes was verified using shear failure specimens from a database to provide suggestions for engineering practice.

An experimental study on the in-plane seismic performance of the confined semi-interlocking masonry system using DIC method

A new earthquake-resistant system for masonry buildings was hypothesised based on utilising Semi-Interlocking Masonry (SIM) panels in Confined masonry (CM) system. This combination was named Confined Semi-Interlocking Masonry (CSIM) and aimed to further improve the seismic performance of confined masonry currently used in buildings. In a CSIM system, walls are intended to resist both gravity and lateral loads, and they simultaneously act as the energy dissipation device for the building. In previous studies, the CSIM system was introduced, and numerical detailed micro and macro models were developed to represent the in-plane behaviour of CSIM. In the current study, the structural capacity, and the seismic performance of CSIM is assessed by performing an experimental in-plane cyclic test on a full-scale CSIM wall. The Digital Image Correlation (DIC) method is employed to observe the crack patterns and the displacement of the wall at different stages of the testing. According to the key findings from the laboratory test, a suitable structural performance with significant values of energy dissipation is attained from the CSIM wall.

In-plane seismic performance of rammed earth walls: an eastern Croatia reconnaissance based study

In-plane seismic performance of rammed earth walls: an eastern Croatia reconnaissance based study

Experimental study and mechanism analysis of out-of-plane seismic performance of reinforced concrete shear walls

Compared with the in-plane seismic performance, the out-of-plane seismic performance of reinforced concrete shear walls is weak and usually neglected, which leads to an inadequate study of the out-of-plane damage mechanism of shear walls and a lack of clear protective measures. In order to compare the similarities and differences in seismic performance of reinforced concrete shear walls when subjected to in-plane and out-of-plane loads in different directions and to clarify the key influencing factors, low cyclic loading tests were carried out on typical shear wall specimens in both in-plane and out-of-plane directions. The moment-curvature simulations of shear wall sections in both in-plane and out-of-plane directions are analyzed. The effects of parameters such as axial pressure ratio, wall thickness, height to width ratio and concrete grade on in-plane and out-of-plane seismic performance were analyzed at the member level in combination with finite element variable parameter analysis; at the structural system level, the time history analysis of 2 frame shear wall structures for single seismic action and main-aftershock sequence is established, and the structural damage is evaluated through the maximum story drift and rotation. The results reveal that the out-of-plane seismic performance of shear walls is significantly weaker than their in-plane seismic performance, with a difference of 1/20∼1/15 times in bearing capacity, where wall thickness and aspect ratio are the main parameters affecting in-plane and out-of-plane seismic performance; when the shear walls in the structure are subjected to seismic action in the out-of-plane direction, their out-of-plane direction will undergo large deformation and damage will occur easily, especially in the Single directional wall with less structure. The out-of-plane nonlinear analysis of the cross-section can be performed more accurately and quickly by using the new principal structure model proposed in this manuscript and some traditional principal structures. In the seismic design of shear walls, both in-plane and out-of-plane seismic performance should be ensured, and the wall thickness and height to width ratio of shear walls should be reasonably controlled.

Role of secondary components in the numerical analysis and in-plane seismic performance assessment of glass curtain walls

Glass façades are complex mechanical systems, in which brittle and vulnerable glass panels interact with metal members and secondary components. Under extreme design actions, such as seismic events, glass failure in tension (cracking) or compression (crushing) is a critical condition for structural performance assessment. Compared to full-scale experiments, in this regard, Finite Element (FE) numerical tools can offer a robust support in design. Besides, many primary and secondary façade components should be properly taken into account, because responsible of possible major approximations in their expected mechanical interactions. In this paper, the in-plane seismic response of glass curtain walls is investigated with geometrically accurate and detailed (“MREF”) or simplified and efficient (“MSIMP”) numerical models. Comparative results are critically discussed, based on dynamic numerical simulations, with a primary attention which is focused on the mechanical performance of glass panels.

Numerical Analysis of Low-Velocity Impact Behaviour of Protective Concrete-Filled Steel Plates Composite Wall.

In this research, a protective concrete-filled steel plate composite wall (PSC) is developed, consisting of a core concrete-filled bilateral steel plate composite shear wall and two lateral replaceable surface steel plates with energy-absorbing layers. The PSC wall is characterised by high in-plane seismic performance as well as out-of-plane impact performance. Therefore, it could be employed primarily in high-rise constructions, civil defence initiatives, and buildings with stringent structural safety criteria. To investigate the out-of-plane low-velocity impact behaviour of the PSC wall, fine finite element models are validated and developed. Then, the influence of geometrical and dynamic loading parameters on its impact behaviour is investigated. The results show that the replaceable energy-absorbing layer could significantly decrease the out-of-plane displacement and plastic displacement of the PSC wall due to its large plastic deformation, which could absorb a significantly large amount of impact energy. Meanwhile, the PSC wall could maintain high in-plane seismic performance when subjected to impact load. The plastic yield-line theoretical model is proposed and utilised to predict the out-of-plane displacement of the PSC wall, and the calculated results agree very well with the simulated results.

In-plane seismic performance of different infill wall systems in ductile reinforced concrete frames

In-plane seismic performance of different infill wall systems in ductile reinforced concrete frames

In-plane seismic performance of an innovative steel modular reinforcement system for URM walls

An experimental and numerical research, aimed at evaluating the in-plane seismic performance of an innovative steel modular system for the reinforcement of load-bearing masonry walls (named "Resisto 5.9", designed by Progetto Sisma s.r.l.), is currently underway at the EUCENTRE Foundation in Pavia. Two different masonry typologies, representing common solutions in Italian existing buildings, were considered in this campaign: one made up with solid clay bricks and lime mortar, with "header bond" pattern, and the other with a typical Italian hollow clay "doppio UNI" unit and cement-lime mortar, assembled in a "Flemish bond" pattern. The experimental tests included first the complete mechanical characterization of units, mortars, masonry typologies and of the strengthening system components (i.e. steel elements and anchors). In-plane quasi-static tests were performed on different batches of full--scale specimens to investigate the influence of the proposed reinforcement system on the lateral in-plane response of the walls, compared to their unreinforced conditions. The cyclic behaviour of the masonry piers was analysed in terms of elastic stiffness, lateral strength, displacement capacity and energy dissipation, depending on the achieved damage mechanism. The numerical study of the ongoing campaign consisted of a series of parametric analyses on advanced discontinuous models based on the Distinct Element Method (DEM), considering different wall dimensions, vertical load levels and boundary conditions, in addition to those tested experimentally. Moreover, the numerical campaign was extended also to other possible masonry typologies, varying the bond pattern and the mechanical properties with respect to the experimentally tested solutions. In this paper, the results of the experimental tests on solid brick masonry together with a preliminary overview of the findings of the numerical study, still ongoing, were reported.

In-plane cyclic behavior of brick walls strengthened with CFRP plates embedded in the horizontal mortar joint

Unreinforced masonry (URM) buildings exhibit significant vulnerability under in-plane seismic loads due to poor tensile strength and integrity. An experiment was carried out to investigate the effectiveness of embedding carbon fiber reinforced polymer (CFRP) plates in the horizontal mortar joint on improving the in-plane seismic performance of URM wall that was prone to fail by diagonal shear failure mode. A total of five half-scale specimens, each measuring 2250 mm × 1500 mm × 240 mm, including two un-strengthened brick walls and three strengthened walls, were tested undergoing pre-compression stress combined with incremental lateral displacement. The CFRP plates were only embedded in the wall on one side in order to reduce the impact on building appearance and different reinforcement ratios were adopted. The failure mode, hysteretic behavior, shear strength, ductility, stiffness degradation and energy dissipation capacity of the specimens were discussed. The results showed that reinforcement can control the initiation and rapid growth of diagonal shear cracks. The strengthened masonry walls exhibited flexural rather than brittle shear failure with good ductility and energy dissipation. The ductility of the strengthened walls increased significantly with the increased reinforcement ratio and there was an optimal reinforcement ratio that maximized the ductility. The strengthened wall with medium reinforcement ratio showed the highest increase in ductility factor of 45.71% compared with the control specimen. The strengthened specimens displayed greater bearing capacity compared with the un-strengthened specimen. The largest increase in the shear strength of the strengthened walls was 10.16%, which indicates the effectiveness of the reinforcement method of used to embed CFRP in the horizontal joint to improve the in-plane seismic performance of URM walls. In addition, the abilities of several analytical models used to predict the shear capacity of the URM and strengthened walls were analyzed.

Study on the influence of constructional column on the seismic performance of infilled wall frame structure

Aiming at the problems of poor construction quality and low efficiency in the construction of cast-in-situ constructional columns, this paper puts forward a kind of fabricated constructional column. Through four full-scale model tests and numerical simulation, the hysteretic energy consumption, stiffness degradation and deformation capacity of infilled wall frames with fabricated constructional columns were studied. The results showed that the specimens with fabricated constructional columns have good in-plane seismic performance. The test phenomenon showed that the crack development mode of masonry infilled wall was changed by the setting of cast-in-situ constructional columns, and its failure was mainly the “X" shaped shear crack. The failure of the infilled wall without any constructional column or with the fabricated constructional column was mainly caused by the horizontal slip cracks. Compared with the cast-in-situ constructional column specimens, the fabricated constructional column specimen has low damage characteristics under the same drift. Finite element simulation can effectively fit the failure and seismic performance of the specimens. This paper can provide references for the application of the new construction technology.

Seismic performance evaluation of non-structural light-gauge-steel frame drywall partition subjected to in-plane cyclic loading

A light-gauge-steel (LGS) drywall partition is an interior non-structural wall system widely used for frame buildings across the globe. In Japan, this system features a sliding track-stud connection of the base frame. An experiment was conducted to investigate the in-plane seismic performance of a typical light-gauge-steel (LGS) wall constructed in accordance with Japanese practice. Fifteen light-gauge-steel (LGS) walls were subjected to in-plane cyclic loading, and the results showed that the degree of damage was related to the envelope curves of the strength-story drift ratio relationship of light-gauge-steel (LGS) specimens. The characteristic points of the envelope curve were defined based on the test results to generate the performance level of the light-gauge-steel (LGS) wall. By evaluating these characteristic points, equations for strength, stiffness, and story drift ratio were established. The prediction results from the equations of drift ratio were found to be within the safe margin. Subsequently, the equations were adopted to define the damage limit states based on damage observations during the test.

Seismic Performance Target and Fragility of Masonry Infilled RC Frames under In-Plane Loading

Masonry infilled RC frames are one of the most common structural forms, the damage of which, in earthquake events, usually cause serious losses. The determination of the seismic performance target is the key foundation of performance-based seismic evaluation and design for masonry infilled RC frames. In this paper, an extensive database of experimental tests on infilled RC frames loaded in an in-plane direction is collated. According to the crack propagation and elastic-plastic characteristics of infilled RC frames, the damage process is divided into four stages, and then the criteria of the damage states (DS) are proposed. In addition, the seismic performance targets expressed as inter-story drift ratio (IDR) for the four stages are suggested, which would support the performance-based in-plane seismic analysis of infilled RC frames. Finally, the proposed in-plane seismic performance target is utilized to analyze the fragility of two masonry infilled RC frame structures.

In-Plane Seismic Behavior of Brick Masonry Walls Reinforced with Twisted Steel Bars and Conventional Steel Bars

The in-plane seismic performance of old unreinforced brick masonry walls strengthened with stainless-steel twisted bars and conventional steel bars (usually used in concrete reinforcing) was investigated in the present study. For this purpose, a total of seventeen masonry wallettes reproducing masonry walls of traditional Lisbon buildings from the 1930s–1950s (known as “placa” buildings) were constructed. The specimens were assembled using original bricks from demolished old buildings and a sand-cement bedding mortar with the same proportions as reported in building design documents of the time. Out of the fourteen wallettes tested in diagonal compression, three were unreinforced, and eleven were strengthened in different layouts. Additionally, axial compression tests were performed on the other three unreinforced masonry wallettes. The tested specimens were reproduced with numerical models calibrated based on the experimental results. The experimental and numerical results of the reinforced specimens were compared to the unreinforced specimens to draw conclusions on the effectiveness of the strengthening solutions when applied to masonry walls of the typology under study. The most important result of the strengthening was an important increase in the ductility of the specimens that were originally brittle. In addition, in some cases a slight increase of shear strength was also observed.

In-plane seismic performance of open masonry walls retrofitted with steel-bar truss units

In this experimental study, the in-plane seismic performance of masonry walls with openings that were incorporated with external prestressed truss units was evaluated based on cyclic loading tests. The external prestressed truss units comprised two vertical, two diagonal, and two horizontal members. In addition, prestressing force was applied to the vertical members. Each unreinforced masonry wall (URM) exhibited an open window or an open door. Meanwhile, the reinforced masonry wall comprised four external prestressed truss units, which were installed on the front and back of the wall-piers on both sides of the opening. The peak strength of the reinforced masonry wall with window opening increased by 146%–153% compared with that of the URM. Furthermore, the peak strength of the reinforced masonry wall with door opening increased by 120%–144% compared with that of the URM. Moreover, the energy dissipation capacity of reinforced specimens increased more compared with that of URM. However, the proposed reinforcement technique does not increase the overall displacement capacity as all the specimens at the same target drift ratio ended up with a stability problem. In addition, the strengthening method did not improve the effective stiffness and ductility of the reinforced masonry wall, and they were lower than that of the URM. The masonry walls reinforced with external prestressed truss units exhibited behavior similar to those of a moderate coupled wall. As there was no retrofitting unit in the upper beam of the opening, shear failure occurred at the interface between the wall piers and upper beam.

A simplified method for seismic assessment of unreinforced masonry buildings

ABSTRACT The paper presents a simplified vulnerability assessment method for unreinforced masonry buildings based on the evaluation of a few structural parameters, which can be determined from visual inspection and a geometry survey. The authors proposed an empirical approach with the aim to assess the in-plane vulnerability quickly by predicting the damage failure of bearing masonry walls. Field observations reveal different behaviours: out-of-plane and in-plane seismic responses. Several simplified assessments focus on out-of-plane behaviour. Few studies deal with in-plane seismic behaviour, which is also the expected response for more masonry buildings. The proposed seismic method provides a vulnerability index, which is evaluated as the weighted sum of 10 parameters markedly affecting the in-plane seismic performance. The reliability of the method is investigated through an application on buildings located in Central Italy, damaged by the 2016 earthquake. The mean damage and damage probability distributions were predicted for each building using the proposed method. Then, fragility functions were estimated from the results of non-linear static analysis, and the damage probability distributions were derived. The capability of the simplified method to foresee the damage probabilities was confirmed by a comparison between different approaches, confirming the reliability of the method in large-scale seismic assessment.

Experimental study on out-of-plane behaviour of an infilled masonry wall with damping layer joint

A damped infilled wall (DIW) is an innovative configuration for improving the in-plane (IP) seismic performance of infilled masonry walls (IMWs) through the introduction of a damping layer joint (DLJ). The out-of-plane (OOP) behaviour of IMWs in an earthquake event plays an important role in their overall seismic performance. This study is aimed at the further investigation of the OOP behaviour and resistance mechanism of a DIW. The OOP behaviour and resistance mechanism of a DIW with a modified-asphalt-waterproof-based (MAW-based) DLJ and mortar-based DLJ are investigated. The results indicate that a DIW with a MAW-based DLJ resists the OOP force mainly via the bending of the masonry unit, while this occurs via the coupled arching action and bending of the masonry unit in the case of a DIW with a mortar-based DLJ. The deformation and damage pattern for the DIW with a MAW-based DLJ and mortar-based DLJ are characterised by the fracture lines of the one-way and two-way slabs, respectively. The OOP capacity of the DIW with a MAW-based DLJ is much lower than that of the DIW with a mortar-based DLJ; however, both of these exhibit ductile behaviour and possess the capacity to resist the maximum earthquake action of the main seismic countries or regions. The DIW is able to remain stable when the OOP displacement at the wall centre reaches 1.2 times the wall thickness.