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1.
Strength characteristics of stone masonry 总被引:2,自引:0,他引:2
K. Venu Madhava Rao B. V. Venkatarama Reddy K. S. Jagadish 《Materials and Structures》1997,30(4):233-237
This paper deals with an experimental investigation on the strength of stone and stone masonry. Granitoidgneiss is commonly used for masonry construction in India. The compressive strength of stone has been determined through 80 mm size cubes. It has been found that the compressive strength of granitoid-gneiss is greater when the load is parallel to the mineral bands. The compressive strength of stone masonry was studied through masonry prisms using 1∶4 and 1∶8 cement mortars. These tests have revealed that masonry strength is higher when the load applied is parallel to the mineral bands. The flexural bond strength of stone masonry walls was studied through full-scale tests. Flexural bond strength appears to play a major role in the failure of stone masonry walls. 相似文献
2.
Alexander Frank Sandra Heinrichsberger Thomas Kranzler Jürgen H. R. Küenzlen Norbert Sack 《Mauerwerk》2020,24(1):37-44
Burglary resistance with lightweight concrete masonry The product palette of lightweight concrete blocks ranges from heavy, high‐strength blocks for internal walls, cavity walls and externally insulated (ETICS) external walls to lightweight, highly insulating blocks with lower density and lower compressive strength for monolithic external walls. In the German National Annex to EN 1627, suitable wall constructions for the installation of burglary‐retarding building elements are given. Masonry walls made of heavy, high‐strength blocks fulfil all requirements up to the highest resistance class RC 6. The installation of burglary‐retarding building elements in modern, highly insulating blocks for monolithic masonry is therefore not covered by the standard yet. At the institute for window technology in Rosenheim (ift Rosenheim), testing has been undertaken of the burglary resistance of building elements installed in monolithic masonry made of highly insulating lightweight concrete blocks. For the usual 365 mm thick lightweight concrete masonry units of compressive strength class 2 and density class 0.40 with a lightweight plaster of Type I, the burglary resistance class RC 2 (recommended by the police in Germany) was verified in all the investigated variants of blocks. The results of the research project have been implemented in a proposed change of the German National annex to DIN EN 1627. 相似文献
3.
The application of three different intervention techniques on three-leaf rubble stone masonry walls are discussed here. Injections, repointing, and the placing of ties connecting the two external whytes were considered, both singularly and in combination. Lime-based products were chosen for injection grouts and repair mortars, to ensure better compatibility with the original materials. The experimental tests, performed on seventeen large scale samples under compressive loads, showed that: (i) injections are very effective to improve the mechanical characteristics of the walls; (ii) the other techniques have less influence on the strength but can operate in avoiding ‘brittle’ failure modes (ties placing) and in improving the durability of the masonry (repointing); (iii) the combination of the techniques ensures the enhancement of the global behavior of the walls. The integration of the experimental results with data available in literature allowed the calibration of an analytical model able to predict the compressive strength of injected walls, based on parameters given by simple experimental tests. 相似文献
4.
In many towns in the south of Italy are present archeological ruins, churches, castles, aqueducts, bridges, retaining walls, private houses which are made of tuff stones coupled with bricks according to a traditional technique named “listed masonry”. Although these structures represent an important part of the cultural heritage of Italy, up till now no studies, devoted to experimentally characterize this kind of masonry, are available in literature. The present paper originates from this lack and focuses on the compressive behavior of tuff-brick listed masonry panels. The results, deduced from an experimental investigation carried out by the authors during the first phase of a research program, are presented in detail. Moreover, numerical analyses aimed at emphasizing further aspects and considerations have been also performed and the obtained results have been analyzed in the light of both the experimental evidences and the directions contained in many current guidelines. The results emerged from this study underline some peculiarities concerning the role of brick-bands on the compressive behavior of the examined panels, particularly in terms of strength, stiffness and cracking configuration. 相似文献
5.
农村房屋抗震是我国防震减灾工作的重要内容。砖砌体结构作为农村房屋的主要结构形式,如何提高其抗震能力具有重要研究意义。为研究砂浆强度、构造措施和窗洞口对砖砌体抗震性能的影响,该文首先对农村砖砌体房屋常用的几种砂浆和砖砌体进行了抗压强度试验,得到了相应材料及构件的强度参数;然后对不同砂浆强度、不同构造措施和开洞的12个墙片进行了拟静力试验,对比分析了不同因素对墙体力学性能影响。试验结果表明,砂浆强度影响最大,构造措施和开洞影响次之。最后依据试验分析结果为我国农居防震减灾工作提出建议。该文相关研究可为农居的抗震设防、标准制定以及施工提供参考。 相似文献
6.
Mojmir Uranjek Vlatko Bosiljkov Roko Žarnić Violeta Bokan-Bosiljkov 《Materials and Structures》2012,45(6):861-879
The injection of grout into multi-leaf stone masonry walls with a sufficient amount of voids can be an effective technique
for the seismic strengthening of such walls. In order to evaluate the effectiveness of different types of commercial grouts
that fulfilled the adopted criteria, the stone masonry walls of an actual building were strengthened by means of grout injection,
using cement and combined cement–lime grouts. The quality and effectiveness of grout injection technique was assessed by non-destructive
tests (sonic and radar tests), minor destructive tests (surface and in-depth probing and coring, and the double flat jack
test), and destructive test (shear-compressive test), all in situ. Preliminary laboratory tests were also performed on mortar
and stone specimens, on the injection grouts, and on cylinders representing the inner core of the strengthened walls. Finally,
the seismic resistance of the building was evaluated in non-strengthened and strengthened variants (i.e. after grout injection
of the walls with cement or lime–cement grout) by means of non-linear static analysis, using the pushover method. Obtained
results show that shear characteristics of the walls (tensile strength and stiffness) depend significantly on the type and
properties of the injected grout, i.e. on the grout’s ability to achieve a solid bond between the stones and the leaves including
the properties (strength and stiffness) of the grout itself. In the case of the type of masonry under consideration, an adequate
level of seismic resistance can be achieved also by using combined cement–lime grouts, although cement grout can provide higher
seismic resistance. 相似文献
7.
Reinforced bending load‐stressed masonry – Suggestions for future designs / Bewehrtes biegedruckbeanspruchtes Mauerwerk – Vorschläge für zukünftige Bemessungen 下载免费PDF全文
Prof. Dr.‐Ing. Erhard Gunkler 《Mauerwerk》2015,19(6):453-470
European standardization bodies are currently working on the amendment to EN 1996‐1‐1, which will also affect the evaluation of reinforced masonry in Germany. For that reason, discussion suggestions are being made here for revisions to lay the groundwork for building materials evaluations and especially, evaluations of bending load‐stressed masonry walls or beams at their serviceability limit state (SLS) for load‐bearing capacities. Information already presented in E DIN 1053‐3:2008‐03 [N3] is being incorporated as well. Characteristic values for the compressive strength of the masonry parallel to the bed joints fk,∥ are essential for the design of reinforced masonry, although they are currently not included in national application documents for Germany. For the time being, they can be mathematically calculated using conversion factors for the characteristic compressive strength values vertical to the bed joints fk or by using the declared axial compressive strengths of the masonry units. The ultimate strains for masonry in general should be set consistently at ?mu = ∣–0.002∣ as several masonry types do not exhibit higher compressive strain values. The use of steel strains higher than ?su = 0.005 does not change any measurement results. Varying stress‐strain curves of the constitutive equations on masonry under compressive strain (parabolic, parabolic‐rectangular, tension block) lead to differing values of recordable bending moments despite having the same mechanical reinforcement percentage at higher normal forces. Therefore, clear guidelines should be made for the type of applicable constitutive equation for masonry walls under compressive strain. With the introduction of a tension block, the number values of the reduction factors λ for the compression zone height x, which is dependent on limit strains, and where applicable, reduced compressive strength, need to be determined, as with reinforced concrete construction. A modification of the bending moment based on the second order theory according to [N4] is presented for the calculation of reinforced masonry walls in danger of buckling. The use of reduction factors for the load capacity of the masonry cross section, such as for unreinforced masonry, does not appear to be appropriate as buckling safety evidence because here, the design task is the determination of a required reinforcement cross section. 相似文献
8.
为研究高延性混凝土(HDC)加固无筋砖墙的抗震性能,设计制作了3片HDC面层加固砖墙、1片钢筋网水泥砂浆面层加固砖墙和1片作为对比试件的未加固砖墙,通过拟静力试验,研究了HDC面层加固砖墙的破坏形态、滞回性能及耗能能力。试验结果表明:HDC面层可对墙体形成约束作用,延缓墙体开裂并改变墙体的破坏模式,提高墙体的承载力和延性;与钢筋网水泥砂浆面层加固相比,单面HDC加固的墙体开裂荷载与耗能能力明显提高,承载力下降缓慢。针对试件的破坏形态,考虑未开裂区加固面层对墙体水平承载力的贡献,提出了加固墙体的承载力计算方法,并根据试验结果进行了验证。 相似文献
9.
Daniel V. Oliveira Rui A. Silva Enrico Garbin Paulo B. Louren?o 《Materials and Structures》2012,45(8):1259-1276
The paper summarizes the results of an experimental research carried out on three-leaf masonry walls of typical granite stone constructions from the North of Portugal. The research aimed at studying the behaviour under compression of this wall typology, as well as the improvements introduced by common strengthening techniques applied for the structural rehabilitation of masonry heritage buildings. Ten masonry specimens were tested, plain or strengthened by transversal tying of the external leaves, with GFRP bars, or/and by injection of the inner leaf, with a lime-based grout. The results obtained showed that these strengthening techniques were successful in increasing the compressive strength of the walls and in improving their behaviour under compressive loads. 相似文献
10.
Shear resistance of masonry walls and Eurocode 6: shear versus tensile strength of masonry 总被引:2,自引:2,他引:0
Miha Tomaževič 《Materials and Structures》2009,42(7):889-907
In the case of masonry structures subjected to seismic loads, shear failure mechanism of walls, characterised by the formation
of diagonal cracks, by far predominates the sliding shear failure mechanism. However, as assumed by Eurocode 6, the latter
represents the critical mechanism for the assessment of the shear resistance of structural walls. The results of a series
of laboratory tests are analysed to show that in the case of the diagonal tension shear failure the results of the Eurocode
6 based calculations are not in agreement with the actual resistance of masonry walls. The results of calculations, where
the diagonal tension shear mechanism and tensile strength of masonry are considered as the critical parameters, are more realistic.
Since the results of seismic resistance verification, based on the Eurocode 6 assumed sliding shear mechanism, are not in
favour of structural safety, it is proposed that in addition to sliding shear, the diagonal tension shear mechanism be also
considered. Besides, in order to avoid misleading distribution of seismic actions on the resisting shear walls, the deformability
characteristics of masonry at shear should be determined on the basis of experiments and not by taking into account the Eurocode
6 recommended G/E ratio. 相似文献
11.
This paper presents the behaviour in compression of an innovative reinforced masonry system. The system is made of horizontally
perforated units, having common steel bars or prefabricated trusses as horizontal reinforcement. At the wall edges or crossings,
confining columns for vertical reinforcement are built with vertically perforated units. Experimental tests, aimed at obtaining
basic mechanical characterisation of the construction system, were performed on single constitutive elements i.e., confining
columns and masonry panels made of horizontally perforated units, and on completed reinforced masonry walls. Non-linear numerical
models, interpreting stress and strain distributions, were developed on the basis of the results. In particular, this paper
presents: (a) results of compression tests on columns, masonry panels, and complete reinforced masonry system; (b) comparison
of walls built with two types of horizontal reinforcement; (c) outcome of numerical models; and (d) effectiveness of various
design equations to evaluate the compressive strength of the system. 相似文献
12.
13.
Increase of the vertical load carrying capacity of masonry due to mortar bed joints with textile glass mesh reinforcement From a structural point of view, one of the most important material parameters in the construction sector is the vertical compressive strength of masonry, which consists of the compressive strength of the bricks as well as of the mortar bed. The interaction between the bricks and the mortar beds is the main reason for compression failures of masonry walls. A close analysis of the deformation behavior of the two components shows that different transverse strains in the contact surface between the bricks and the mortar are the main cause for compression failures. However, the load‐bearing capacity of masonry walls can be increased by using some reinforcement in the mortar beds which counteracts lateral expansion. The impact of textile glass mesh reinforcement on the load‐bearing capacity of masonry was analyzed in a test program on masonry columns with different numbers of textile glass mesh reinforced mortar beds. The results of the analyses show that the load‐bearing capacity of the columns rises with an increased ratio of reinforcement, regardless of the type of bricks used. From the ratio of the height of the reinforcement layers to the thickness of the wall it can be deduced that a higher degree of reinforcement has a positive effect on the load‐bearing capacity of the masonry. On this basis, an increase of the strength and load‐bearing capacity of masonry walls is formulated to be on the safe side. 相似文献
14.
Lessons learned from the testing of RC frames with masonry infills and proposals for new solutions / Untersuchungen an mit Mauerwerk ausgefachten Stahlbetonrahmen und neue Lösungsvorschläge 下载免费PDF全文
Prof. Paulo B. Lourenço Dr. Graça Vasconcelos Dr. João Leite Dr. Paulo Pereira 《Mauerwerk》2016,20(2):99-123
Past experience has shown that inadequate design of unreinforced masonry walls (URM) or inadequate selection of materials can lead to significant economic losses and fatalities in the case of a strong earthquake. In this context, this paper presents the experimental research that has been carried out with the aim of gaining a better insight into the traditional masonry infill walls commonly built in Portugal. The experimental research includes: (1) shaking table tests on reduced‐scale reinforced concrete (RC) buildings with masonry infills with distinct typologies, from traditional solutions to those with enhanced properties and solutions to improve the seismic behaviour; (2) in‐plane static cyclic tests on a representative one‐storey, one‐bay RC frame with masonry infills with distinct typologies but similar to the ones tested in the RC building models. It was concluded that the typology of masonry walls influences the global behaviour of RC buildings, particularly when there is no connection between masonry infill and RC frame. An appropriate design is necessary to prevent an unforeseen failure mechanism due to shear stresses in the RC columns induced by the infill. The in‐plane cyclic tests showed that render plays a central role in the lateral strength and stiffness. Additionally, it was observed that bed joint reinforcement and reinforced render are important measures for controlling damage but do not significantly influence the in‐plane lateral strength and stiffness. 相似文献
15.
Experimental and analytical investigation of the seismic out‐of‐plane behavior of unreinforced masonry walls In addition to the vertical and horizontal load‐bearing in‐plane, masonry must also withstand out‐of‐plane loads that occur in earthquake scenarios. The out‐of‐plane behavior of unreinforced masonry walls depends on a variety of parameters and is very complex due to the strong non‐linearity. Current design methods in German codes and various international codes have not been explicitly developed for out‐of‐plane behavior and contain considerable conservatism. In the present work, shaking‐table experiments with heat‐insulating masonry walls have been conducted to investigate the out‐of‐plane behavior of vertical spanning unreinforced masonry walls. As shown in previous numerical investigations, important parameters are neglected in existing design and analysis models and the out‐of‐plane capacity is underestimated significantly. In the conducted experiments the results of these numerical investigations are verified. Furthermore, the development of an analytical design model to determine the force‐displacement relationship and the out‐of‐plane load‐bearing capacity considering all significant parameters is presented. 相似文献
16.
In the last two decades, the use of pumice as lightweight aggregate for concrete in structural applications has been the object
of different studies. The aim was to find out if pumice can be an alternative to ordinary lightweight aggregate. The present
paper is framed in this context. Here, a study is presented showing the use of pumice for making lightweight concrete units
for masonry members. Through the paper, the formulation of a mix design for lightweight concrete is proposed. Then the obtained
mechanical characteristics of the masonry units are discussed and compared to the code requirements. Reinforced bearing masonry
walls, made with the concrete masonry units in question, were made and tested under lateral cyclic loads. For comparison,
lightweight concrete units and bearing walls made using expanded clay were constructed and tested in order to show if pumice
can also be considered as an alternative to ordinary lightweight aggregate in the case discussed here. 相似文献
17.
随着石材开采和切割技术的发展,建筑砌筑条石正从传统手工粗细料石逐步向机器切割条石过渡。机器切割条石砌筑石墙灰缝界面性能与传统石墙灰缝存在较大差异,开展其灰缝抗剪性能研究是机器切割条石砌筑石墙推广应用的关键。该文通过15 片新型机器切割条石无垫片砌筑石墙灰缝双剪试验,研究这种新型石墙灰缝的抗剪性能。主要的研究参数包括砌筑灰浆强度、压应力水平和界面处理方式。根据试验结果,分析各因素对灰缝的受力特点、破坏模式、界面抗剪强度和变形性能的影响,同时基于正交试验分析各因素对灰缝抗剪性能的影响程度。研究结果表明:新型机器切割条石砌筑石墙灰缝的破坏呈现脆性破坏,灰缝开裂即达最大承载力,同时灰缝迅速滑移;各研究参数对灰缝抗剪性能的影响程度依次为界面处理方式、压应力水平和灰浆强度。通过对试验数据的统计回归,提出机器切割条石砌筑石墙灰缝的抗剪强度计算公式,计算结果和试验值吻合程度较好,可以用于工程设计和实践。 相似文献
18.
Valeria Corinaldesi 《Cement and Concrete Composites》2009,31(7):505-510
Mortars containing recycled aggregate, instead of quartz sand, were characterized to find an alternative application for the fine recycled-aggregate fraction coming from building debris processing. Tests on bond strength of mortar to masonry units were carried out, as well as tests on compressive and shear strengths of masonry assemblages. The results obtained were related to the mechanical properties of mortars and brick. On the basis of the characterization results and performance evaluations, recycled-aggregate mortar appears to be superior to ordinary mortars in terms of mortar–brick bond strength and shear strength of masonry assemblages. This improved performance is of particular interest for the masonry structures in zones of seismic activity. In addition, the use of fine recycled aggregate is in accordance with the sustainable development concept, where recycling of building rubble plays a key role in ending the building life cycle. 相似文献
19.
Masonry strength is dependent upon characteristics of the masonry unit, the mortar and the bond between them. Empirical formulae
as well as analytical and finite element (FE) models have been developed to predict structural behaviour of masonry. This
paper is focused on developing a three dimensional non-linear FE model based on micro-modelling approach to predict masonry
prism compressive strength and crack pattern. The proposed FE model uses multi-linear stress–strain relationships to model
the non-linear behaviour of solid masonry unit and the mortar. Willam–Warnke’s five parameter failure theory developed for
modelling the tri-axial behaviour of concrete has been adopted to model the failure of masonry materials. The post failure
regime has been modelled by applying orthotropic constitutive equations based on the smeared crack approach. Compressive strength
of the masonry prism predicted by the proposed FE model has been compared with experimental values as well as the values predicted
by other failure theories and Eurocode formula. The crack pattern predicted by the FE model shows vertical splitting cracks
in the prism. The FE model predicts the ultimate failure compressive stress close to 85% of the mean experimental compressive
strength value. 相似文献
20.
砌体墙在竖向压力和平面内水平剪力复合作用下的破坏准则是确定砌体抗剪承载力的重要依据。通过对比分析, 推导出基于最大主应力理论、剪摩理论、Mohr 理论和变形能理论的适合于砌体在剪压复合作用下的破坏准则。考虑到微元体与宏观墙模型的差别, 建立了相应于各种破坏准则的砌体抗剪承载力计算公式。并将公式的计算结果与收集的111 片普通粘土砖砌体墙片的试验结果进行了对比分析, 得到了常用多层砌体房屋墙的抗剪承载力计算公式。 相似文献