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An experimental and numerical research, aimed at evaluating the in-plane seismic performance of an innovative external steel modular system for the strengthening of load-bearing masonry walls, is currently underway at the EUCENTRE Foundation in Pavia. This paper presents, in particular, the results of the experimental part of this research campaign. Solid clay brick and hollow clay "doppio UNI" masonry typologies, representing common solutions in Italian existing buildings, were considered. After the mechanical characterization of the masonry and of the components of the reinforcement system, cyclic in-plane pseudo-static tests on full-scale specimens were performed in order to investigate the influence of the proposed system on the in-plane response of the walls, compared to the unreinforced conditions. The main seismic parameters of the masonry walls (i.e. elastic stiffness, lateral resistance, displacement capacity and energy dissipation) were assessed depending on the achieved damage mechanism. The proposed reinforcement system provided very promising results, improving the in-plane seismic performance of masonry walls at serviceability and especially at ultimate conditions, with a significant increase of deformation capacity above all in the case of shear mechanisms. [ABSTRACT FROM AUTHOR]

A simple and accurate analytical model for defining the lateral strength of the multi-span RC frame with masonry infill has been developed in this study. This model is developed due to the limitation of the current analytical model which only can be applied to the single-span RC frame. Meanwhile, the structure in the building also is in a multi-span frame and masonry infill greatly impacts the portal structure. In the existing building, this analytical method is needed to calculate the lateral strength of the RC frame. Besides, the analytical method was developed based on the lateral strength analysis method of a single-span RC frame in which the modeling of a multi-span RC frame with masonry infill along with uniform span spacing was applied. Furthermore, an equivalent diagonal strut with the same thickness and material as the masonry panels was used instead of masonry infill in the frame structure. The external column has diagonal compressive forces on the top or bottom of the column. On the other hand, diagonal compressive forces work at the top and the bottom of the column in the internal column. The lateral strength of the infill was determined based on the frame infill contact length. Furthermore, in order to obtain the lateral strength of the structure, the experimental study of a multi-span RC frame with masonry infill under cyclic load was also tested. Applying the analytical model has shown promising results even after being compared with the results of the experimental work. [ABSTRACT FROM AUTHOR]

This paper studies the lateral strength of traditional (unstabilized) adobe walls subjected to lateral loading, either in-plane or out-of-plane, using the finite element method. The focus of the numerical parametric study is on adobe walls that have a moist region in their lower part immediately above the footing. The variables of the parametric study are the length, height, and water content of the moist region. The lateral strength of adobe walls can be affected by the moist region depending on its size and water content. Generally, the threshold of gravimetric water content of the moist region associated with a considerable decrease in lateral strength is 12% for I-shaped walls under in-plane lateral loading and 10% for cantilever walls under out-of-plane lateral loading. A short moist region that is at most one-third or one-fourth of the wall length for out-of-plane or in-plane loading, respectively, does not compromise significantly the wall lateral strength even at relatively high water content. Even though the results depend on the model geometry and characteristics, this information can be useful to those working in adobe repair and preservation because approaching or exceeding these limiting water contents might indicate an immediate need for shoring the walls. [ABSTRACT FROM AUTHOR]

This article discusses the results of an experimental program to retrofit unreinforced masonry walls by means of diagonal and vertical steel strips. The technique has several advantages such as simplicity to apply, relatively low costs, and insignificant disruption of service functions during the repair. The tests were conducted on three specimens: two with both diagonal and vertical steel strips and one with only diagonal steel strips, and all attached to one face of the walls. The tests showed that the steel strips improved lateral strength, increased non-linear displacement capacity, and changed the nature of the failure modes. [ABSTRACT FROM AUTHOR]

This paper discusses the experimental results for defining the seismic performance of the brick masonry infilled reinforced concrete (RC) frame with a central opening under lateral static reversed cyclic loading. The influence of the presence of the rebar reinforcements on the opening interface to the masonry is compared to the opening without rebar reinforcement. In this study, six of 1/4 scale-down of single-story singlebay RC frame specimens have been constructed and tested. These specimens included one bare RC frame, one unreinforced brick masonry infilled RC frame, two unreinforced brick masonry infilled RC frames with a central opening and two brick masonry infilled RC frames with a central opening embedded with 2Ø6 horizontal steel reinforcements above and below of the opening. The ratios of opening size to the panel area of the infilled specimens were 25% and 40%. The experimental results confirm that the existence of the opening reduces the stiffness, the lateral strength and energy dissipation of the RC infilled frame system. However, the infilled frames with 25% and 40% opening ratios show better performance compare to bare frame specimen. Although the strengthening by using embedded rebars does not significantly increase the performance of the RC frame system, the brick infill with horizontal reinforcements installed above and below the opening was verified to resist large deformation of masonry infill in out of plane direction. [ABSTRACT FROM AUTHOR]

Highlights • A dataset collecting the results of 188 in-plane cyclic tests on URM piers has been developed. • Different masonry typologies constituted by bricks and blocks are included. • A preliminary investigation on the in-plane lateral strength and displacement capacity has been performed. • Some inconsistencies between code criteria and experimental evidence have been pointed out. • The dataset provides a tool available for future studies on the in-plane response of URM piers. Abstract In this paper, a dataset collecting the results of in-plane cyclic tests on unreinforced masonry piers, carried out within different research projects, is presented. The dataset includes brick and block walls with different materials, bed-and head-joint typologies, dimensions, boundary conditions and vertical applied loads. The development of such dataset aims at providing a tool for the improvement of the understanding and the evaluation of the main parameters that may influence and govern the lateral response of the URM piers under seismic excitation. A preliminary investigation on the in-plane lateral strength and displacement capacity, being two of the most significant parameters used in seismic analyses for the design and assessment of masonry buildings, has been proposed. The dataset, that already groups several specimens, is freely shared and might be continuously updated. This source of information of consistent and reliable test results represents a necessary step into the process of definition of shared rules within the scientific and technical community, in particular for the improvement of codified criteria, analytical and numerical models and testing procedures. [ABSTRACT FROM AUTHOR]

This article proposes a numerical modeling approach to account for the weakening effect of moisture on the in-plane (lateral) resistance of adobe masonry walls. The approach uses a variable that links the water content of the soil to its strength properties, with varying locations of a moist region in the wall (i.e., length across the wall). A nonlinear, isotropic finite element model was used to study adobe walls at the macro scale. The adequacy of the proposed approach was examined numerically through finite element (FE) analysis for I-shaped adobe walls with varying length and water content of a moist region along the base. The analysis showed that the lateral strength of adobe walls, defined as the maximum force required to cause a given displacement, may drop considerably (up to about 40% for the cases considered) depending on the length, location, and water content of the moist (weakened) region of the wall. [ABSTRACT FROM PUBLISHER]

This paper presents the results of several experimental campaigns recently carried out by the authors and devoted to the investigation of the mechanical performance of wall panels strengthened by applying repointing mortar and high strength stainless steel or composite cords. The reinforcement system, known as Reticulatus, allows the reinforcement of regular and irregular-shape masonry walls, when the fair-faced aspect must be kept. In the perspective of using this reinforcement method, this article summarizes the research that has been done so far, presenting new original test results and discussing the design procedures. Twenty-two square wall panels were loaded in their plane by means of a single point load acting through the panel's diagonal. Experimental results are presented for four types of cord reinforcement using matched samples, reinforced and not. Increases in shear strength from 15 to 170 % were achieved for the strengthened panels. Each wall panel was loaded well into the lateral post-elastic regime and then unloaded. Experimental results were in good agreement with predictions from simple models which assume the wall panels to behave like a plate, neglecting the contribution of the repointing mortar, and accounting for the non-linear behavior of the masonry. [ABSTRACT FROM AUTHOR]

This study presents an experimental study on responses of eight constrained masonry walls with tie columns and ring beams, subjected to in-plane cyclic loading before and after being retrofitted with basalt-fiber-reinforced polymer (BFRP). Among these eight walls, two without any strengthening measures served as reference specimens; two were directly strengthened with horizontal and diagonal BFRP strips after they were constructed; and the rest were tested to defined damage levels and then repaired for retesting. The opening in the wall, the layer of the BFRP strip, and the vertical compression level were considered in the test design. Experimental results showed different failure modes of the specimens. Details of testing results were discussed regarding strength and drift, hysteretic characteristics, stiffness degradation, energy dissipation, and BFRP strip strains. A performance comparison analysis was also conducted between the constrained masonry walls and the unreinforced ones. Finally, a calculation method was proposed to estimate the ultimate lateral strength of BFRP retrofitted masonry walls. [ABSTRACT FROM AUTHOR]