Masonry Sections Research Articles

Structural Analysis of Steel Truss and Masonry Bridge Interaction: A Case of Ali Fuat Pasha Bridge in Sakarya, Türkiye

Restoration of historical structures using new materials and techniques is widespread worldwide. In these applications, relatively new materials such as steel, concrete, reinforced concrete (RC), or composite are generally preferred. However, it is often ignored whether old materials and new materials work in compatibility. In this respect, Ali Fuat Pasha Bridge (or Bayezid II Bridge), which was built by Bayezid II in 1495 over the Sakarya River in Geyve-Sakarya, was examined. The bridge is 196.50 meters long and consists of 15 arches with different spans and three arches of the bridge were destroyed as a result of the earthquake. Then, the bridge has been restored by constructing a steel truss system in place of the destroyed arches. Within the scope of this study, the structural performance of the bridge, which is currently serving vehicle and pedestrian traffic, is examined by using finite element analyses (FEAs). Moreover, this research examines the combined behavior of steel and masonry materials and investigates the structural behavior of steel truss and masonry bridge interaction. According to the results of the analyses, there are significant behavioral differences between the masonry structure and the steel structure. The main cause for this disparity is thought to be the varying levels of stiffness and ductility in steel and masonry sections.

Unified Theory for Flexural Strengthening of Masonry with Composites.

Recent calamitous events have shown the fragility of the existing masonry buildings. Many of them are heritage structures, such as churches and monumental buildings. Therefore, optimized strengthening strategies are necessary. Experimental studies performed on masonry elements strengthened with composite systems have shown the performance of these materials. However, further development is necessary to optimize the intervention strategies. In fact, due to the lack of general validity models, the design is usually based on prescriptive approaches according to manufacturers’ broad instructions, often producing systems with low efficiency and overestimations of the amount of reinforcement. In this paper a generalized approach is proposed to assess the flexural behavior of masonry sections strengthened with composites. The proposed theory has allowed performance of a sensitivity analysis assessing the impact both of the mechanical parameters of masonry and of the strengthening system. In particular, the impact of several constitutive relationships of composites (linear, bilinear, or trilinear) have been evaluated in terms of ultimate behavior of the strengthened masonry. For strengthening systems more compatible with the masonry substrate, the form of the stress–strain relationship becomes a key aspect. For such cases, the modeling of the reinforcement plays a fundamental role and the form of the relationship is strongly correlated to the type of reinforcement selected, e.g., organic versus inorganic matrix.

Bemessungshilfen für biegedruckbeanspruchtes unbewehrtes Mauerwerk – Teil 2: Anwendung von Bemessungshilfen für die Bemessung nach DIN EN 1996‐1‐1/NA

AbstractThe semi‐probabilistic safety concept of divided safety factors for action and resistance of DIN EN 1990 [1] in combination with the structural design codes DIN EN 1996‐1‐1 [2] and DIN EN 1996‐1‐1/NA [3] include the requirement that acting normal forces NEd may not exceed the normal force resistances NRd for the structural design of masonry under bending compression. According to [3], fully plastic material behaviour can be assumed and the stress block used as the material law for masonry.Building on this, design aids and their theoretical basis were presented in Part 1 of this scientific paper [4], which are comparable with the ω tables (called the ɸ table here) and the general design diagram for massive construction.The application of the design aids is described in this second part of this scientific paper through calculation examples and the connection with the calculation approaches of [3] is made clear.The relation to the reduction factor ɸm, which covers effects of 2nd order theory, is also obtained. With known values of the load eccentricities according to 1st and 2nd order theory, the design task becomes the analysis of the loadbearing capacity of the masonry section at half wall height. Knowing ɸm, the load eccentricity e2 and the additional moment according to 2nd order theory can subsequently be determined, which does not ensue from the calculation equations of [3].With the general design diagram, the values of compression zone height and the assumed load eccentricities of the acting normal forces, which result from the reset rule for masonry sections with high load eccentricities, can be directly read off, greatly improving the clarity of this procedure.

Design aids for unreinforced masonry under bending compression – Part 1: Basics

AbstractThe semi‐probabilistic safety concept of divided safety factors for action and resistance of DIN EN 1990 [1] led in Germany to a comparison of resisting bending moments and normal forces with the corresponding acting section forces and moments in the structural design of masonry building elements.Regarding the material properties for masonry under bending compression, fully plastic material behaviour is assumed in DIN EN 1996‐1‐1/NA [2]. The use of a stress block has been introduced as a material law, which results in the reduction factor ϕ for the determination of the loadbearing capacity of the section. This describes the ratio of the normal force resistance of the reduced (due to the bending effect) part of the design section under compression and the resistance value related to the total area.Building on this, design aids are presented here, which are comparable with the ν tables (called ϕ table here) and the ”general structural design program“ of massive building, since common mechanical basics permit this.The user‐friendly handling of the design diagram and design tables is demonstrated through examples in the second part of the scientific paper [3] and the relation to the calculation approaches of DIN EN 1996‐1‐1/NA [2] is made clear. The relation to the reduction factor ϕm, which takes into account the effects of second order theory, is also described in [3], like the use of the reset rule for masonry sections with normal forces acting with large load eccentricities.

SURVEY, HBIM AND CONSERVATION PLAN OF A MONUMENTAL BUILDING DAMAGED BY EARTHQUAKE

SURVEY, HBIM AND CONSERVATION PLAN OF A MONUMENTAL BUILDING DAMAGED BY EARTHQUAKE

Cálculo en agotamiento de secciones de fábrica reforzadas a flexión con láminas de FRP

Masonry structures can hardly resist tensile loads. For this reason these structures are vulnerable to accidental actions, such as earthquakes, or when they suffer damage that change their geometry conditions, for instead, due to differential soil settlements. This paper presents an ultimate limit state method for checking FRP-strengthened unreinforced masonry sections. The method is similar to the one used for reinforced concrete members, but it is adapted to masonry and FRP laminates particularities. In this proposal a bilinear strength-strain relationship is used and the FRP design strain is limited to take into account different aspects which cause the plate can’t reach its ultimate strength. In particular, it is proposed a “bond reduction factor”, derived from a large bending test database.

Assessment of mechanical properties of full-scale masonry panels through sonic methods. Comparison with mechanical destructive tests

Sonic tests are a valid and useful non-destructive method for qualitative characterization of masonry elements. If sonic tests are applied with the right configuration, the results can identify discontinuities in masonry sections and provide the morphology of a construction typology, contributing to the assessment of built heritage as demanded by the international recommendations on this domain. The elaboration of data from sonic tests applied to masonry structures has been essentially based on the evaluation of the P waves' propagation through the masonry thickness, that is, by using the direct sonic method, a procedure that has been calibrated for many years by different authors. However, recent studies have shown that indirect configurations through the indirect sonic impact method may be used to estimate the mechanical properties of stones masonry samples. This procedure allows assessing not only P but also R wave propagation, permitting to estimate the deformability characteristics of masonry panels. Under this research, a set of stone masonry specimens was tested using both direct and indirect sonic impact methods and later assessed through laboratory mechanical compression tests, a procedure's sequence that allow validating the sonic tests capabilities. Copyright © 2015 John Wiley & Sons, Ltd.

Simple Tests and Mechanical Model for Masonry Materials at High Temperatures

An experimental procedure for tests on specimens made of several materials is performed to detect the mechanical properties depending from temperature. About 200 cylindrical specimens of several materials (clay, lightweight concrete, aerate autoclaved concrete, mortar) are tested from 20°C to 700°C. The free thermal strain and the decay of axial strength are determined; proposals for the stress-strain curves and the secant modulus of elasticity in function of temperature are illustrated. The data base from tests are able to calculate the collapse domains (bending moment - axial force - time of exposure to nominal fire) which represent a simple model for the assessment of masonry panel sections subjected to fire action.

Out-of-Plane Seismic Capacity of Masonry Depending on Wall Section Morphology

To what extent does a wall subjected to out-of-plane seismic action behave monolithically and fail by overturning or, conversely, split into separate leaves? How much does the workmanship—the set of construction specifications that historical treatises collect under the definition of “rule of art”—influence the structural behaviour of the wall? These research topics have proved highly significant in the recent seismic events, but yet remain insufficiently known and handled without the appropriate analysis tools. In this article, the dependence of the out-of-plane seismic capacity of masonry walls on the morphology of the wall section is investigated starting from real masonry sections, surveyed from historic buildings, which are modelled using the distinct element method. The seismic capacity is estimated by pushover analyses with uniform increasing horizontal forces and dynamic analyses under acceleration pulses. The results highlight the effective reduction in strength and displacement capacity of masonry sections depending on the transverse bond provided by stones.

Influence of cavity dimension on the stability of eccentrically loaded slender unreinforced masonry hollow walls

Results of nonlinear finite element analyses of slender unreinforced masonry (URM) hollow walls under eccentric vertical load and with different cavity depths are presented, with emphasis on critical axial loads. The walls were analyzed using a nonlinear finite element formulation that was verified with published results from experiments on slender URM walls. The analysis indicates that for small amounts of bending from eccentricity, critical load decreases as cavity depth increases; while for moderate or large amounts of bending, there exists a nontrivial optimal cavity depth that maximizes the critical load. In some cases, critical load for a hollow wall is larger than that for a similar solid wall. In comparing the analysis results with code provisions for URM stability in the United States of America (USA), the treatment of eccentricity in hollow masonry sections was found to be adequate. However, code provisions cannot be used to simulate the observed reductions in bucking loads associated with compression softening from material plasticity. Moreover, commonly-used effective height factors from elastic stability theory can lead to overestimation of critical axial loads. Further study of these issues is needed.

Modeling of Out-of-Plane Behavior of Masonry Walls

The flexural behavior of rectangular masonry sections is investigated by considering nonlinear stress-strain in compression and limited-tension material. A preliminary analysis shows that, with variation in the parameters specializing with the adopted conventional constitutive law, the experimentally observed behavior of different kinds of masonry materials can be approximated. Subsequently, moment-curvature dimensionless curves are derived numerically by satisfying the equilibrium equations of the section. In the case of negligible tensile strength these curves exhibit a typical shape that can be approximated by analytical expressions; consequently, suitable functions are proposed that are governed by only a few parameters which depend on the compression level of the section and the available ductility of the material. The reliability of the proposed modeling procedure is also verified by using the experimental results of a previous study, where masonry elements subjected to an increasing eccentric normal load were considered. Therefore, the analytically defined flexural behavior is transferred to the characteristic sections of a discrete model of slender masonry column, in order to reproduce the experimental results of full-scale tests on bearing masonry walls subjected to increasing lateral deflections for stability analyses. Comments on the results obtained with this model would be useful for further investigations.

Out-of-plane strength of brick masonry retrofitted with horizontal NSM CFRP strips

The magnitude of damage possible in unreinforced brick masonry construction subjected to high levels of out-of-plane loading is well understood. Due to the large global building stock of masonry structures, it is essential that efficient retrofitting techniques be developed. The use of fibre-reinforced polymer (FRP) strips has been shown to improve the load-carrying and displacement capacities of masonry sections subjected to out-of-plane loading. This paper presents the results of an experimental and theoretical investigation into the behaviour of modern clay brick masonry retrofitted with horizontally oriented FRP strips subjected to horizontal bending. Experimental tests were conducted on four masonry wallettes retrofitted with horizontal near-surface mounted (NSM) carbon FRP strips, subjected to horizontal bending. The specimens were tested in a vertical orientation with variation in vertical compressive loading. The application of compressive load improved the FRP confinement efficiency, and thus increased the maximum strength of the specimens. The primary failure modes were displacement induced (DI) debonding and FRP buckling. Mathematical models were developed to predict the moment at cracking and moment capacity for the specimens. The models explicitly account for the flexural strengths of the mortar and brick units, the torsional resistance of the bed joints, the NSM FRP, as well as the contributions to bed joint shear strength from the vertical compressive stress and friction. The proposed mathematical models were validated against the results of the experimental tests.

Moment/thrust interaction diagrams for reinforced masonry sections

This paper presents a numerical analysis for estimating moment/thrust interaction diagrams for reinforced masonry sections. Realistic constitutive models are used for the masonry and steel reinforcement. Considering compatibility of strains and equilibrium of forces on reinforced masonry sections, the moment–curvature relationships for different axial thrusts are first produced. The moment–thrust interaction diagrams are then developed. Comparisons between the behaviour predicted using the current method and experiments conducted on reinforced and unreinforced masonry short columns are presented to examine the validity of the developed method. Finally, a parametric study of the material properties is undertaken.

Moment Capacities of Unreinforced Masonry Sections in Bending

Current unreinforced masonry design relies on limited models of flexural behaviour in the orthogonal and inclined directions, which are partly empirical and do not fully account for the beneficial effects of compressive stress. This paper presents the results of a theoretical and experimental investigation to develop improved expressions for the horizontal and diagonal bending moment capacities contributing to the ultimate wall strength. The new expressions were verified against experimental data and were shown to give accurate predictions of the bending strength for 63 full-scale wall panels, including walls with openings, using the virtual work method of AS 3700.

Reducing water losses from channels using linings: Costs and benefits in Pakistan

To evaluate the effectiveness of various types of linings in reducing the seepage losses from field channels, 10 conventional and 12 low cost test sections were constructed. The conventional test sections included six rectangular brick masonry sections and four trapezoidal concrete sections with varying thickness of walls and bed lining materials. The low cost sections consisted of six rectangular brick masonry sections and six trapezoidal sections with brick masonry, pre-cast concrete slab and tile lining having different thickness of wall and bed linings. In some low cost sections lining was not provided in the bed. Water loss rates were measured before construction, immediately after construction and 24 years after construction. Higher seepage loss rates were measured in the cement–concrete conventional test sections than in the conventional brick masonry sections with plaster on the inside walls. Water loss rate measurements in concrete sections showed that quality control was more critical than the thickness and richness of the concrete mix. Economic analyses showed that low cost linings were a better investment than the conventional linings. Low cost lining with 11 cm thick brick masonry in vertical walls, or 2:1 sloped walls, plastered on the inside, without lining in the bed, is recommended. Lining walls, with 2:1 slope, using fired tile or pre cast concrete slabs were also good investments when the joints were plastered.

Experimental study on the determination of strength of masonry walls

The results of a research project carried out on masonry panels obtained from structures struck by the Umbria-Marchigiano earthquake of 1997–1998 are presented. The project consists of two parts: tests were performed in the laboratory, and in situ in order to determine the correct parameters describing masonry behavior. With regard to the laboratory tests, several compression tests were performed on cylindrical stone samples. Stone samples were obtained from the panels on which in situ tests had been previously carried out. Depending on the three types of in situ tests carried out (compression test, diagonal compression test, shear–compression test), different dimensions of panels were used using an appropriate cutting technique in order to leave the panels undisturbed. The shear strength and the Young and shear elastic modulus were measured. These results were compared with the values suggested by different standards. The experimental research allowed to characterize the mechanical properties of some typical masonry walls in old buildings of Umbria. These results are reported, together with an analysis of the masonry textures and sections.

Flexural bearing capacity and related ductility demand for masonry sections under nonlinear constitutive law

This paper aims at examining the maximum bearing capacity of rectangular masonry cross-sections subjected to eccentric compression, by assuming a nonlinear constitutive law characterized by two parameters defining stressstrain curve of the material. The variation of these parameters permits us to represent a wide variety of materials; therefore the ductility required of these materials in order for a section to achieve the maximum bending moment compatible with an average normal stress is also determined. The proposed approach can be utilized to evaluate the safety condition of masonry bearing walls, like those characterizing buildings of historical andfor monumental interest, for which the stress state can become dangerous because of eccentricity in the loads or due to horizontal seismic forces. Some experimental tests confirm the reliability of the proposed procedure.

Estimating processes of smaller builders

The paper describes a study of the way in which smaller builders price items in bills of quantities for competitive tender. A series of interviews revealed some marked differences between normal practice and literature-based prescriptions. An experiment was conducted in which eight practising builders’ estimators were separately presented with a representative sample of 36 bill of quantities items taken from groundwork, in situ concrete work and masonry sections. The estimators stated the method they would normally use to price each item, their ‘normal’ price rate and their highest/lowest price rate. The results showed that only half the items would be priced by the prescribed ‘detailed’ method, the remainder being priced mainly by ‘experience’. Analysis by work section, item rate, item quantity, item total, item labour content, contribution to the total of the bill, the standard deviation of the interestimator intraitem rates and totals and their coefficients of variation, skewness and kurtosis indicated...