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The explosions caused by terrorism and/or accidental lead to serious damage and/or collapse in structures, economic losses, and most importantly endanger public safety. The blasting loads that can be larger than design loads are generally neglected in the design stage of civil engineering structures, despite these catastrophic effects. For these reasons, especially strategically important structures such as hospitals, military buildings, and bridges should be designed considering the blasting effects. To this aim, the effects of design parameters such as concrete strength and openings in infill walls on blasting responses of reinforced concrete (RC) buildings are investigated in this study. In situ experimental tests are firstly conducted on a test specimen constructed with brick elements to verify the finite element (FE) model criteria and assumptions. The blasting experiments are performed using 40, 150, and 290 g trinitrotoluene (TNT) explosives. Then, two RC buildings are selected as application, and blasting analyses are done with numerical and empirical methods. FE models of the buildings including structural and non-structural elements are constituted in ANSYS Workbench software. The blasting analyses are carried out with ANSYS AUTODYN software using 100 kg TNT explosives. In the analyses, two different openings in infill walls and six different concrete classes are considered. The blasting pressures, displacements, absorbed and released total energies, and damage ratios are obtained and presented as comparison parameters. The results obtained from the blasting analyses are presented with graphics and tables, comparatively. The study shows that peak pressures and maximum displacements decrease by 22.50% and 32.16% with the increase in concrete strength. Also, it is observed from numerical analyses that openings in infill walls lead to a change of 8.16% in peak pressures and 13.92% in maximum displacements.

The external envelope walls of a significant percentage of the residential building stock in Southern European countries is commonly constituted by infill masonry walls. However, thousands of square meters of this masonry wall typology presents severe issues of cracking and instability, related to the incorrect and deficient support conditions of the outer brick panel of the double-leaf wall solution. In this work, an experimental campaign divided in two phases has been performed to evaluate the effectiveness of two different remedial wall ties retrofitting techniques (Solution A and Solution B) used for double leaf horizontally hollowed clay brick masonry fa&ccedil, ades. The first phase of the experimental campaign was performed on 120 isolated specimens of horizontally hollowed clay bricks, resorting to post- and pre-NP EN 771-1 brick exemplars (that is, new and pre-existent aged bricks, respectively), as well as on 4 square wallettes, with a side length of 1.20 m, considered as representative of a real scale scenario, for evaluating the two remedial wall ties retrofitting techniques. The second phase of the experimental campaign was performed to fully characterize the different failure types as well as the slipping phenomena observed in the first phase of the experimental campaign, focusing solely on the retrofitting technique Solution B and comprises 24 tests performed on isolated specimens, resourcing to new and pre-existent aged bricks as well. The results obtained by the use of these techniques revealed an average anchorage strength value ranging from 0.25 to 2.5 kN for each tested tie-bar. Solution B reveals an increase of double of the anchorage strength value in comparison to Solution A. In this sense, the global results revealed a suitable applicability of both retrofit studied solutions.

Infill walls, which are generally assumed as dead loads in building design, affect the lateral resistance, stiffness, and energy consumption of the frames. Investigations conducted after earthquakes show that the infill walls, whose effects are neglected in the design, can change the earthquake behavior of the structure and cause unforeseen damages in the buildings and even collapses in some cases. In order to match the behavior of designed and built frames, the technique of isolating the infill wall from the RC frame with non-interacting infill was adopted. In this study, in-plane behavior of bare, traditionally infilled frames and a frame with non-interacting infill wall were investigated experimentally under reversed cycling loads, then their numerical models were calibrated. As a result, in contrast to the traditionally infilled frame, it has been seen that the frame with non-interacting infill behaves close to the bare frame in the initial drifts and maintains its lateral resistance without a damage until further drifts. Therefore, it has been found that constructing the infill wall with non-interacting joint improves the in-plane behavior.

Lateral stiffness provided by infill walls to the building structures is generally neglected in designs. Infill walls, which are only included in the calculations as dead loads, significantly affect the lateral resistance, stiffness and energy dissipation of the frames. Both the studies in the literature and the infill wall damages observed after the earthquake support the existence of these unforeseen effects in the design. It is an important problem to reflect the infill wall effects to the site application as designed. In this study, the solution to isolate the infill walls from the load-carrying frames is adopted. Three different flexible connection elements designed in this context were examined experimentally and numerically, their in-plane behavior was compared with bare and traditionally infilled frames. As a result of the study, it was observed that the frames with flexible connections behaved close to the bare frame in the initial drifts, unlike the fully infilled frame behavior, which significantly lost its lateral resistance in the initial drifts, and continued its lateral resistance without any damage until further drifts. It is thought that the flexible connections will be an important development in terms of compatibility of design and site applications.

Masonry infill walls are commonly used in the frames of reinforced concrete (RC) buildings around the world. The seismic performance of these buildings is strongly affected by the presence of the infill walls and partitions, as shown by the post-earthquake damage in many cases. The effect of these components is particularly important for RC frame constructions underdesigned for seismic actions that usually are characterized by deformable frames magnifying the contribution of the infill walls to the seismic response. Also the flexibility of the floors could be influenced by the collaboration of the infill walls to the transversal stiffness of the building. The paper addresses the seismic assessment of a typical infilled RC frame building designed only for gravity loads in the 1960s in the Southern of Italy that currently is a high-seismic zone. The structural identification of the building based on ambient vibration test has been already done pointing out the significant role of infill walls and partitions through the updating of the numerical model. Based on the results of the calibrated model, the effect of the floor flexibility on the dynamic behavior of the structure is discussed, and the seismic capacity at life safety limit state (LSLS) is assessed by means of the linear dynamic analyses. The effects of the infill walls on the seismic performance of the building are discussed in detail considering a strengthening solution that involves the infill panels as masonry walls cut from the RC columns to avoid the local interaction but strengthened by composite grids in mortar matrix (FRCM).

Infill walls are commonly used in RC frame structures but are neglected in the structural analysis. It is well known that infill walls could have a significant effect on the structural performance of RC frames under seismic actions, as recently occurred in Italy during the L’Aquila event; furthermore, in many cases, the damage to infill walls is due to out-of-plane actions that can pose a risk to human life (falling of heavy parts). The current paper addresses the behavior of out-of-plane infill walls by conducting parametric linear dynamic time-history analyses. The scope of the parametric study is to evaluate the seismic demand of out-of-plane infill walls by considering the variation of the walls’ properties and the position in the building. Finally, the code provisions for evaluating the seismic action on the infill walls by equivalent static forces are examined and compared with the analytical results from the detailed dynamic analysis.

The paper describes the results of quasi-static tests performed on a real-scale adobe masonry infill wall partitioned into sub-panels by means of the introduction of vertical wooden planks, acting as sliding joints. The specimen was tested both in-plane and out-of-plane, exhibiting good performance in terms of both stability against out-of-plane actions and in-plane deformation capacity and damage control. The results emphasize the applicability of adobe masonry as material for infill walls in seismic prone regions, coupling the good structural response with the inherent positive performance in terms of indoor ambient comfort and production sustainability demonstrated in literature.

The recent earthquakes that occurred in Central Italy, in L’Aquila in 2009 and in Amatrice in 2016, have shown, once again, how infill panels and partitions, widely used as non-structural elements in reinforced concrete frames, are significantly vulnerable when subjected to seismic actions. Moreover, they highly affect the structural behavior and seismic response of typical, multi-story buildings, strongly influencing their repair costs due to the inevitable damage they usually undergo during seismic events. Therefore, they should be designed to withstand earthquakes forces, both in-plane and out-of-plane, so to ensure the safety of the occupants. In addition to seismic performance, infill panels play the primary role of providing comfort to occupants through adequate thermal and acoustic insulation. In this paper, an innovative solution of earthquake-safe and eco-friendly infill panels is presented, which are, at the same time, thermally and acoustically efficient, thus avoiding waste of energy and respecting the environment. The proposed innovative technology is tested with different surface finishes, boundary conditions and temperatures. A comparison of the proposed technology with respect to conventional infill typologies is provided, highlighting pros and cons.

In 1999 Marmara and 2011 Van earthquakes in Turkey, majority of the existing buildings either sustained severe damage or collapsed. These buildings include masonry infill walls in both the interior and exterior R/C frames. The material of the masonry infill is the main variant, ranging from natural stones to bricks and blocks. It is demanding to design these buildings for satisfactory structural behavior. In general, masonry infill walls are considered by its weights not by interaction between walls and frames. In this study, R/C buildings with infill walls are considered in terms of structural behavior. Therefore, 5 and 8-story R/C buildings are regarded as the representative models in the analyses. The R/C representative buildings, both with and without infill walls were analyzed to determine the effects of structural behavior change. The differences in earthquake behavior of these representative buildings were investigated to determine the effects of infill walls leading structural capacity. First, pushover curves of the representative buildings were sketched. Aftermath, time history analyses were carried out to define the displacement demands. Finally, fragility analyses were performed. Throughout the fragility analyses, probabilistic seismic assessment for R/C building structures both with and without infill walls were provided. In this study, besides the deterministic assessment methodology, a probabilistic approach was followed to define structural effect of infill walls under seismic loads. © 2013 Techno-Press, Ltd.

URL: http://sujest.selcuk.edu.tr/sumbtd/article/view/355 DOI: 10.15317/Scitech.2016320517, Having poor seismic performance reinforced concrete frame must be strengthened to reach sufficient seismic performance. The main factor that affects the seismic performance, designing and application of the anchor dowels in the connection zone of infill shear wall and weak reinforced frame. Connection between the frame and the infill wall are usually achieved by using dowels that are placed in the holes drilled into inner faces of the frame members, and fixed by a resin. In this study, the design and detailing guidelines for the design of the post-installed anchors in TEC (2007), ACI 318, JCI (2001) and IS15988 have been compared. According to the results, in ACI 318-14, the shear capacity of anchors is effected by embedment depth, anchor bar diameter, concrete strength, strength of the bar and edge distance. In TEC-2007, shear strength is affected only by two properties of the anchor bar: strength and diameter. JCI-2001 design code considers the two factors outlined in TEC-2007 and concrete strength. Based on the comparison conducted in this study, there are insufficient guidelines in TEC-2007 for the design and detailing of anchor bars that are typically used as connection between an existing frame and new RC infill wall., Deprem performansı yetersiz olan betonarme çerçevelerin yeterli performans seviyesine gelebilmesi için betonarme perde duvarlar ile güçlendirilmesi gerekmektedir. Sonradan yapılan betonarme perde duvarların davranışını etkileyen en önemli unsur çerçeve ve betonarme duvar arasında bağlantı olarak kullanılan ankrajların tasarımı ve uygulamasıdır. Çerçeve ve betonarme dolgu duvarlar arasındaki bağlantı genellikle çerçeve parçalarının iç yüzeylerine açılan deliklere yerleştirilen ankraj donatılarının reçine ile sabitlenmesiyle elde edilir. Bu çalışmada ankrajlar için TEC–2007, ACI 318–14, JCI–2001 ve IS1–5988 gibi yönetmeliklerde verilen tasarım kuralları karşılaştırılmıştır. Yapılan karşılaştırmaya göre ACI 318-14’te, ankrajların kesme dayanımının gömme derinliği, donatı çapı, beton dayanımı, ankraj donatı dayanımı ve kenar mesafesi ile ilişkili olduğu görülmüştür. TEC-2007’de ise ankrajların kesme dayanımı sadece ankraj donatısının çekme dayanımı ve ankraj çapından etkilendiğinden bahsedilmektedir. ISI–5988, JCI-2001’in TEC- 2007’ gibi beton basınç dayanımına dikkat ettiği görülmüştür. Bu çalışmada dört yönteminde kıyaslanması sonucunda, mevcut çerçeve ve yeni betonarme dolgu duvar arasında bağlantı olarak kullanılan ankrajlar için TEC-2007’nin yetersiz kaldığı görülmüştür

An innovative technique is being developed for the structural rehabilitation of Reinforced Concrete (RC) structures. In particular, the infill walls of RC framed structures are often identified as non-structural elements, but currently are considered with an important role in the structural behavior because they participate to the in-plane strength and stiffness of the frames and they can give very dangerous crashes out-of-plane. In this paper a strengthening technique aimed to repair infill walls is proposed. It is based on the application of outer thin layers of ultra-high ductile fiber reinforced mortar (UHDFRM) applied according to the shotcrete technique, including the use of embedded through section (ETS) connectors. This strengthening system can exhibit a high strength and ductile behavior, increase the load carrying capacity, energy absorption and dissipation capacities, and ultimately improve the structural response of RC structures when submitted to loading conditions typical of seismic events. An experimental program was outlined in order to assess the contribution of different types of ETS connectors on the behavior of the strengthening system. The experimental program comprised the performance of push-out tests on samples representative of the structural strengthening solution, namely low strength concrete samples. The experimental results are discussed in detail in order to highlight the effectiveness of the various types of ETS connectors tested., The authors acknowledges the support provided by the project n. 23024, INOTEC - Innovative material of ultra-high ductility for the rehabilitation of the built patrimony, co-financed by the European Regional Development Fund (FEDER) through the Operational Program COMPETE. The collaboration provided by Owenscorning (glass fibers), Exporplas (polypropylene fibers), Fisipe (PAN Fibers), Sika (superlasticizers), Pegop (Fly ash) and PIEP (in the preparation of the connectors) are acknowledged.

In literature, there are many methods proposed for structural analysis based on discrete element formulations, mainly for nonlinear problems. One of these new methods is the Fibre Contact Element Method (FCEM). Many of these methods have been used for structural dynamic analysis problems. However, there are some questions about their precision in capturing the dynamic elastic response of structures when comparing to methods based on continuous models, like the well known Finite Element Method (FEM). For this reason, the results obtained with FCEM were extensively compared with FEM results and with laboratorial tests, to better understand the performance of this new method in capturing the elastic dynamic response of structures. Results indicate that this kind of discrete methods are able to determine the vibration modes of a structure with equal or better precision level than the obtained with FEM. FCEM was also used to capture the dynamic response of a reinforced concrete frame with infill walls, as a way to show the method capabilities in reproducing the dynamic behaviour of structures that have an almost continuous mass distribution.

This paper presents a pushover analysis using ABAQUS (Dassault Company, Providence, Rhodes Island, USA) for spatial reinforced concrete (RC) frames. The main purpose is to study the effect of the infills on failure patterns of the RC frames. The Finite Element Method (FEM) model considered an RC frame with fulfilled infills, half-filled infills, and without infills. Column moment, the effective width of the cast in situ slab, and the required ratio of column to beam strength are calculated and analyzed. Research findings indicate that the location of the inflection point varied because of the effect of infills. Some of the calculated values of column moments are larger than those values according to the design code. The effective slab width and the required ratio of column to beam strength are found to be reduced due to the infill effects. The actual effective width of the slab should be considered in the required ratio of column to beam strength. Reasonable advice is proposed and discussed for design purposes.

The vulnerability of the masonry envelop under blast loading is considered critical due to the risk of loss of lives. The behaviour of masonry infill walls subjected to dynamic out-of-plane loading was experimentally investigated in this work. Using confined underwater blast wave generators (WBWG), applying the extremely high rate conversion of the explosive detonation energy into the kinetic energy of a thick water confinement, allowed a surface area distribution avoiding also the generation of high velocity fragments and reducing atmospheric sound wave. In the present study, water plastic containers, having in its centre a detonator inside a cylindrical explosive charge, were used in unreinforced masonry infills panels with 1.7m by 3.5m. Besides the usage of pressure and displacement transducers, pictures with high-speed video cameras were recorded to enable processing of the deflections and identification of failure modes. Additional numerical studies were performed in both unreinforced and reinforced walls. Bed joint reinforcement and grid reinforcement were used to strengthen the infill walls, and the results are presented and compared, allowing to obtain pressure-impulse diagrams for design of masonry infill walls., This work was performed under Project CH-SECURE, with reference PTDC/ECM/120118/2010, funded by the Portuguese Foundation of Science and Technology - FCT. The authors acknowledge the support. The first author also acknowledges the support from his PhD FCT grant with the reference SFRH/BD/45436/2008.

The performance of various composite materials applied to strengthen hollow masonry panels under out-of-plane actions is compared here. The strengthening solutions belong to three reinforcement Externally Bonded (EB) wet lay-up systems: (i) bidirectional composite meshes applied with inorganic matrices, i.e., Textile Reinforced Mortars (TRM); unidirectional composite textiles applied with (ii) inorganic matrices, i.e., Steel Reinforced Grouts (SRG), or (iii) organic (epoxy) matrices, i.e., Fibre Reinforced Polymers (FRP), Steel Reinforced Polymers (SRP) and Natural FRPs. Carbon FRP, flax and hemp NFRP, and basalt and glass-based TRM were examined. As inorganic matrix, a cement-based mortar was used for TRMs; in the case of SRGs, comparisons with a magnesia-based matrix were also carried out. Twenty-seven specimens were subjected to simplified four-point monotonic bending tests, aimed at reproducing in the laboratory the failure condition of infill masonry walls under out-of-plane actions. The results are compared in terms of failure mode and mechanical improvement, and provide an analytical evaluation of moment–curvature behaviour according to bilinear laws.

Low and mid-rise reinforced concrete (RC) buildings consist of an important portion of the building stock in many earthquake prone countries. Therefore understanding their seismic behaviour is important for mitigation studies. This study aims to evaluate how much and when; seismic code, number of stories, concrete strength, amount of transverse reinforcement and infill-wall contribution parameters are important for seismic performances of RC buildings. Seismic performances of the models reflecting different cases are determined for different performance levels and seismic loading conditions. Based on the considered values of the parameters, it is concluded that: modern code specifications and higher transverse reinforcement 50%, the concrete strength up to 66%, infill-walls 15% and number of story 55% increase the seismic performance for life safety level. Evaluations on the effect of the considered parameters for different performance levels and seismic loadings in relation with other parameters are also given in this paper. © 2014 Indian Academy of Sciences. :107M569 2010FBE098, 2010FBE099, 2008FBE005 The authors thank the Scientific and Technical Research Council of Turkey (TUBITAK) under Project No:107M569 and support of Pamukkale University Research Fund Unit (PAU-BAP) under Project No: 2008FBE005, 2010FBE098 and 2010FBE099 for support.

The objective of this paper is to study the effects of structural non-linear behaviour on Floor Response Spectra (FRS) of existing reinforced concrete frames. This study examines how the FRS vary with the level of post-elastic behaviour in buildings of different number of stories and masonry infill wall configurations. The effect of damping modelling assumptions is also investigated. Differences and similarities with findings from the literature are discussed. On the basis of the obtained results, a commentary on the adequacy of basic assumptions used in predictive equations proposed by different seismic codes is offered.

This paper discusses the issue of performance requirements and construction criteria for masonry enclosure and infill walls. Vertical building enclosures in European countries are very often constituted by non-load-bearing masonry walls, using horizontally perforated clay bricks. These walls are generally supported and confined by a reinforced concrete frame structure of columns and beams/slabs. Since these walls are commonly considered to be nonstructural elements and their influence on the structural response is ignored, their consideration in the design of structures as well as their connection to the adjacent structural elements is frequently negligent or insufficiently detailed. As a consequence, nonstructural elements, as for wall enclosures, are relatively sensitive to drift and acceleration demands when buildings are subjected to seismic actions. Many international standards and technical documents stress the need for design acceptability criteria for nonstructural elements, however they do not specifically indicate how to prevent collapse and severe cracking, and how to enhance the overall stability in the case of moderate to high seismic loading. Furthermore, a review of appropriate measures to improve enclosure wall performance and both in-plane and out-of-plane integrity under seismic actions is addressed.

Experimental or theoretical tests show that dramatically changes of infill area causes soft story mechanism. "Soft story" mechanism is the most frequent failure mode of reinforced concrete (R.C.) structures. This phenomenon is caused by the fact that the overall shear force applied to the building by an earthquake is higher at the base floor. If the lower story is not originally weakened, it is however there that infill are the most stressed, so that they fail first and create the weak story and finally leads collapse of structures. This kind of collapse was observed many times in Turkey caused by earthquake. The aim of this paper is to show the contribution of infill walls to the building response during earthquake. Different type of configuration of infill walls are modeled and analyzed by the Finite Element Method. These models also have soft story risk. The nonlinear force-displacement behavior is used for structural analysis. El Centro N-S component is used for time-history analysis. © Guney and Aydin.

In designing and implementing earthquake resistance for clay block masonry infill integrated into a structural frame, with or without openings, the infill wall should be taken into account. Presumably, simplified models, acceptable for practical use, could be applied for that purpose. However, the anisotropy of clay block masonry units, masonry mortar joints, and unit contact properties as well as the high variance of material properties limit their ability to describe the actual earthquake resistance of clay block masonry. In this work, we consider a three-dimensional micromodel of a clay block masonry wall, with the inclusion of masonry unit anisotropy and masonry mortar joint and unit contact properties. To avoid the excessive calibration procedure of the wall micromodel, the wall constituents were calibrated separately beforehand, which resulted in a high correlation of computational and experimental results without further need for calibration. Using a calibrated micromodel, the influence of variance in material properties on the wall’s resistance was investigated. The influence was showed not to be negligible, which may significantly affect the presumed behaviour of the whole structure.