Structural Appraisal of the Florentine Gothic Construction System

The nave of Santa Maria Novella, a Dominican church in Florence Italy is representative of a Florentine Gothic system of construction. This system, consisting of domical rib vaults on square nave bays, high side aisles, and crypto-buttressing, differs substantially from the French high Gothic system of even-level-crown rib vaults on rectangular bays, with flying buttresses over relatively low aisles. An investigation into the structural aspects of the Florentine Gothic construction system reveals that the domical vaults increase the longitudinal thrust and reduce the transverse thrust, which may require additional precautions to be taken during construction, but entails a less elaborate buttressing system. The domical vaults are found to perform well structurally, with an absence of tensile stresses, and are more suitable for a square bay. In general, the structural system of the nave of Santa Maria Novella is found to be the product of carefully considered structural design, which may be accepted as an alternative to the French Gothic construction system.     

An analytical model to determine the ultimate load on masonry arch bridges.

This paper proposes an analytical elasto–plastic model to describe the behavior of arches. The modeling is carried out using the equations of (i) horizontal equilibrium, (ii) vertical equilibrium and (iii) equilibrium of moments. The latter equations of equilibrium are ordinary differential equations which can easily be solved by adding boundary conditions, imposing restrictions on the horizontal and vertical movement and on the rotation in the abutments of the arch. For masonry arches, including material properties allowing the occurrence of cracks and the subsequent formation of hinges is required. The latter theory has been implemented in a computer program (Matlab), offering numerical simulations. The software was used to illustrate two case-studies, i.e., the assessment of an arch loaded with a vertical point load and one with a horizontal point load.     

Influence of fly ash and its mean particle size on certain engineering properties of cement composite mortars

An experimental investigation on the effects of incorporating large volumes of fly ash on the early engineering properties and long-term strength of masonry mortars is reported. The effect of fly ash and its mean particle size (PD) on the variation of workability and strength has been studied. It was found that fly ash and its mean particle size play a very significant role on the strength of masonry mortars. It has been observed that the early-term strength, except the mortars incorporating coarse fly ash (CFA), was slightly influenced by the replacement with fly ash. The long-term strength (both the bond strength and the compressive strength) will significantly increase, especially for the bond strength of mortars incorporating coarse fly ash. It was also found that the bond strength significantly increased as the mean particle size of fly ash decreases after 28 days curing. However, the 7-day strength was little influenced by fly ash particle size. The fluidity of composite mortar enhanced due to replace cement and lime with fly ash, and the mean PD of fly ash significantly influenced the workability.     

Best practices for preventing musculoskeletal disorders in masonry: stakeholder perspectives

Brick masons and mason tenders report a high prevalence of work-related musculoskeletal disorders (WMSDs), many of which can be prevented with changes in materials, work equipment or work practices. To explore the use of "best practices" in the masonry industry, NIOSH organized a 2-day meeting of masonry stakeholders. Attendees included 30 industry representatives, 5 health and safety researchers, 4 health/safety specialists, 2 ergonomic consultants, and 2 representatives of state workers' compensation programs. Small groups discussed ergonomic interventions currently utilized in the masonry industry, including factors affecting intervention implementation and ways to promote diffusion of interventions. Meeting participants also identified various barriers to intervention implementation, including business considerations, quality concerns, design issues, supply problems, jobsite conditions and management practices that can slow or limit intervention diffusion. To be successful, future diffusion efforts must not only raise awareness of available solutions but also address these practical concerns.     

Validation of Analytical Multiparameter Homogenization Models for Out-of-Plane Loaded Masonry Walls by Means of the Finite Element Method

The linear elastic analysis of in-plane and out-of-plane loaded masonry walls is still significant under service loads and is required by codes of practice, therefore the knowledge of the homogenized mechanical properties of masonry is of relevant interest. The aim of this paper is to discuss the problem of the out-of-plane loaded masonry walls in detail and to assess the accuracy and reliability of different homogenization approaches presented in the technical literature, with particular interest in recent explicit formulas obtained through an asymptotic model (as reported by Cecchi and Sab in 2002). Several meaningful comparisons are presented for different types of new and historical masonry structures currently employed in Italy. The validation of the analytical models is carried out by means of a three-dimensional (3D) finite-element (FE) out-of-plane homogenization. A final structural comparison among analytical models, FE out-of-plane homogenization, and a computationally expensive heterogeneous 3D FE model is discussed for a simply supported square panel laterally loaded.     

Explosive Testing of Polymer Retrofit Masonry Walls

The most widely used terrorist tactic is the improvised explosive device, which can range in size from hand-held to truck-size. Most casualties and injuries sustained in such an attack are not caused by the blast itself, but rather by the disintegration and fragmentation of walls, the shattering of windows, and by nonsecured objects propelled at high velocities by the blast. Since 1995, the Air Force Research Laboratory at Tyndall Air Force Base has investigated methods of retrofitting wall structures to better resist blast loads from external explosions. This paper summarizes results from recent tests that involve an innovative use of a sprayed-on polymer to increase blast resistance of unreinforced concrete masonry walls. Test methodology, retrofit materials considered, material properties, mechanisms of effectiveness, and research challenges are discussed.     

建筑实践中的材料选择

文章的重点是讨论在具体的建筑实践中材料与建筑的本质性关联,亦即与设计的意图和特征、与建筑的发生密切相关的内容。在多数实践中,设计围绕核心意图展开,在意图的指引下选择对应的材料,形成特定的特征而达到预设的目标;而另外一些实践,则是因既定材料而引发设计,甚至发展出具有持续性的工作和研究方向,如"砌筑"和"组配";材料与空间、结构、形式的同一性也成为近年来特定类型建筑实践中的某种既定追求。     

Closed form solution for predicting the horizontal capacity of masonry portal frames through limit analysis and comparison with experimental test results

The paper deals with the problem of evaluating the in-plane seismic capacity of unreinforced masonry portal frame, which can be considered the basic structural element in historical buildings. In particular, the Limit Analysis approach is used to provide simplified “closed form” expressions of the horizontal collapse multiplier, also taking into account the eventual contribution of steel tie rods. Both sliding shear and shear diagonal cracking are also considered in order to take into account the shear failure modes of the pier walls.The proposed formulations have been used for performing an extensive parametric analysis, with the aim of studying the effect of both geometry and vertical/horizontal loading distributions on the portal horizontal strength. Furthermore, the influence of the steel tie-rods has been addressed in order to understand their effectiveness on the portal seismic capacity.A comparison with the results of experimental tests on full-scale portal frames is also provided in terms of in-plane collapse multiplier and failure mechanism aimed to validate the proposed “closed form” expressions.Major outcome of this study is a simple rule of thumb, which can be used for the straightforward assessment of the horizontal strength of simple masonry structures, and for verifying the results of more complex structural analyses such as the nonlinear static analysis.     

Shear strengthening of wall panels through jacketing with cement mortar reinforced by GFRP grids

This paper gives the results of a series of shear tests carried out on historic wall panels reinforced with an innovative technique by means of jacketing with GFRP (Glass Fiber Reinforced Plastics) mesh inserted into an inorganic matrix. Tests were carried out in situ on panels cut from three different historic buildings in Italy: two in double-leaf rough hewn rubble stone masonry in Umbria and L’Aquila and another with solid brick masonry in Emilia. Two widely-known test methods: the diagonal compression test and the shear-compression test with existing confinement stress. The test results enabled the determination of the shear strength of the masonry before and after the application of the reinforcement. The panels strengthened with the GFRP exhibited a significant improvement in lateral load-carrying capacity of up to 1060% when compared to the control panels. A numerical study assessed the global behavior and the stress evolution in the unreinforced and strengthened panels using a finite element code.     

Failure of structural (RC,masonry, bridge) to Van earthquake

An earthquake occurred on 23 October 2011, at approximately 20 km north of city of Van downtown, west of Ercek Lake, in the vicinity of Kasimoglu Village with a moment magnitude of M_w = 7.2. While aftershock activities of this earthquake continues intensively, another earthquake with local magnitude M_w = 5.6 occurred, on 9 November 2011, at approximately 10 km south of Van downtown, in county of Edremit region. By this second earthquake, property damage and life loss count significantly increased. In this paper, failures of damaged structures at Van earthquake are examined. Also negative effects of structural irregularities (short column, soft story, torsion), structural material (concrete, steel), soil properties (liquefaction, sliding), structural systems (reinforced concrete, prefabricated, masonry and adobe) and structure type (bridge, culvert, minaret) are studied.