Roof Truss Research Articles

Hidden Above Church Vaults: The Design Evolution of Early Iron Roof Trusses in Mid-Nineteenth-Century Belgium

ABSTRACTThis article sets out to assess the first phase of iron roof construction in Belgian churches, from the 1840s to the 1860s, and the evolution of iron roof structures in this period, through an in-depth analysis of four case studies, located in Brussels, Antwerp, and Ghent. The article is based on fieldwork as well as archival and literature research. The cases are contextualized within the architectural, technical, political-economic, and intellectual environment of the time when structural iron was introduced in Belgium: a country that industrialized at an early date, with an iron industry that developed rapidly. The Belgian findings are put into an international perspective. By providing new insights into the early use of iron and the evolution of new construction principles in churches, this study seeks to encourage researchers, architects, and heritage assessors to climb above the vaults of churches and consider the hidden roof structures with greater care.

Buckling behavior of cold-formed stub channels under compression

Channel section is one of the most common cold-formed steel sections uses today. Cold formed steel members are widely used in roof trusses. Yielding and crushing are the modes of failure for short compression members or stub column. Design equations can be used to determine local buckling load capacity of stub column. In building construction, the stub column is found in the roof trusses. The purpose of this study is to understand buckling behaviour of the cold formed stub channels under compression. Seven (7) specimens were tested in this study. The results of local buckling, maximum load capacity and axial displacement of seven (7) cold-formed stub channels specimens were obtained by conducting the stub column test (compression test) and tensile test. Five (5) specimens are conservative to mean ratio and two (2) specimens are unconservative. Load-displacement graphs were plotted and two (2) specimens had achieved the expected curve. The failure patterns of the stub channels showed that the buckling occurred at the top edge and bottom edge of stub channels.

System fragility analysis of roof cladding and trusses for Australian contemporary housing subjected to wind uplift

This paper describes a reliability-based fragility method to evaluate the wind damage to roof cladding and trusses for contemporary houses in non-cyclonic regions of Australia. The fragility assessment considers roof sheeting loss and roof truss failure due to overloading of cladding-to-batten, batten-to-rafter/truss and rafter/truss-to-wall connectors that are typically the ‘weakest links’ of a roof system under wind uplift pressure. The wind fragility herein is expressed by the mean extent of roof sheeting loss and roof truss failures as a function of gust wind speed. Monte Carlo Simulation in conjunction with a finite element approach are employed to carry out the wind fragility assessment, which enables the probabilistic characterization of spatially varying wind uplift pressure, connection resistances, structural response, failure progression of roof connections and internal pressure evolution with increasing roof sheeting loss. The proposed fragility method was illustrated on representative contemporary housing built in Brisbane and Melbourne with complex hip-roof geometries and corrugated metal roof sheeting. It was found that, for the gust wind speed corresponding to a 500-year return period, the mean proportion of roof sheeting loss and roof truss failures is negligible for the representative contemporary house built in Melbourne, whereas considerable roof damage is predicted for those built in Brisbane when windward dominant openings exist.

Estimation of capacity of eccentrically loaded single angle struts with decision trees

Single angle struts are used as compression members for many structures including roof trusses and transmission towers. The exact analysis and design of such members is challenging due to various uncertainties such as the end fixity or eccentricity of the applied loads. The design standards provide guidelines that have been found inaccurate towards the conservative side. Artificial Neural Networks (ANN) have been observed to perform better than the design standards, when trained with experimental data and this has been reported literature. However, practical implementation of ANN poses problem as the trained network as well as the knowhow regarding the application should be accessible to practitioners. In another data-driven tool, the Decision Trees (DT), the practical application is easier as decision based rules are generated, which are readily comprehended and implemented by designers. Hence, in this paper, DT was explored for the evaluation of capacity of eccentrically loaded single angle struts and was found to be robust and yielded comparable accuracy as ANN, and better than design code (AISC). This has enormous potential for easy and straightforward implementation by practicing engineers through the logic based decision rules, which would be easily programmable on computer. For this application, use of dimensionless ratios as inputs for the development of DT was found to yield better results when compared to the approach of using the original variables as inputs.

Pembuatan Rangka Atap dan Sarana Pendukungnya Bangunan Pengolah Sampah Desa Banjararum Kalibawang

Garbage in Banjararum is increasing due to the source of garbage that always increases. The source of garbage comes from stalls, schools, health centers, and agriculture. To handle the garbage needs a solution to reduce the negative impact on health society. Implementation is carried out with stages, measurements, installation of stakes, excavation of foundation, installation of roof, installation of columns, walls, roof truss, and roof cover. Followed by making a machine room, pools to collect the garbage. The results of this community service are that the garbage processing building consists in the engine room, Pools for garbage collection that will be processed.

The experimental study of the effect of screw and adhesive connection in the variation of cold-formed roof truss framing system

onnections with screws are used extensively to connect cold-formed steel (CFS) structural element, especially in the roof truss framing system. However, these connections cannot be relied upon to transfer loading due to the small thickness plates that result in more slender elements which are susceptible to local or distortional buckling and have low stiffness. Therefore, some improvements are made in this study by adding adhesive as the alternative connection. Three types of roof truss framing system are designed with a different connection, i.e. screw, adhesive and the combination of screw and adhesive. The study aims to investigate the behavior of frames connection through experimental studies with the given static load until the frame structure collapses, with attention to their initial (pre-slip) stiffness, elongation, and load-deformation capacity. As a result, the stiffness of adhesive connection given a lower value than screw connection. It is indicated of the delamination process, that the combination connection implied the better behavior with 50% screw reduction as well as increasing the load-deformation capacity with 69.7 mm, three times higher than the screw connection.

Palace of the Earl of Padul, Granada (Spain). A Milestone in A Crossroad

The Palace of the Counts of Padul is the most emblematic building of Padul, Province of Granada in Spain, being one of the most remarkable of the region of the Valley of Lecrín. It is a building of undoubted historical value, declared of Cultural Interest, maximum level of protection of the Spanish legislation in historical heritage. In spite of this and being a symbol of Padul, citizen ignorance is generalized about its importance. It is a building of the first part of the XVII century. D. Antonio de Aróstegui y Zazo (knight of the Santiago order and a secretary of Felipe III) was its developer. He gives the building a noble character with an unusual design for this shire. It has an L shape floor, two floors and two squared towers standing out a third floor covered by a pitched roof. Load-bearing walls of masonry not carved stones, with carved stones corners. Deck built with logs, and bricks, and wooden roof truss. Looking like a solid simple house of civil architecture at the beginning of the Baroque style. Analysing the urban morphology of Padul, the uniqueness and large area of the plot that it occupies with respect to the rest of the urban plot is verified. It is also remarkable its relative position with respect to the historical roads that crossed here: The real road that came from Granada heading to the Alpujarras, and leading to Motril and the road that starting in Malaga crossed through Alhama and arrived at Padul. It is clear then, the function that had as a control post, having been a necessary passage towards the Lecrín Valley, the Alpujarras and the Mediterranean coast. Immediately after its declaration in 1981 as a National Monument, and despite this, it suffered an unfortunate intervention which has been maintained until today and that the City of Padul wants to revert with its acquisition. It is in this situation in which the invitation of the council government to the University of Granada is produced so that the students of Final of Grade Projects of the School of Building Engineering have it as a real object to work. By focusing our attention on this building, it is intended to preserve its valuable heritage, showing its history, proposing technical solutions that help to preserve its values, and finally, to make the Casa Grande popular for the residents of Padul and all visitors.

Behavior and design for component and system of cold-formed steel roof trusses

The experimental investigation of the behavior of cold formed steel (CFS) roof trusses does not offer a prior knowledge about either which member will fail first or the capacity of the whole truss. This research aims to investigate the overall behavior of CFS roof trusses using finite element analysis and to predict the failure location in the truss assembly and its cause by calculating the demand to capacity (D/C) ratios using Direct Strength Method (DSM) for each component of the truss and compare it with finite element results. Twelve trusses were examined under the same gravity load and boundary conditions to study the effect of span, the truss web pattern, and the cross section type of truss members on the ultimate strength of the truss.Results revealed that for longer spans, Fink truss configuration is better than Howe truss. The member with the maximum D/C ratio will be the first member to fail in FEA, so engineer can use D/C components' ratio instead of FEA to predict the first member to fail, the cause of failure, and truss capacity. The results of D/C ratio values showed that each truss was designed with high efficient critical components and highly variable D/C ratios, which increase the probability of producing an alternative load path to the loads that are carried by the failed truss members. The reliability of truss system is much greater than the reliability of any component as the truss system's D/C ratio calculated from FEA is always less than the maximum component's D/C ratio from the design.

Application of Shape Memory Alloys in Historical Constructions

ABSTRACTA device prototype, based on the superelastic properties of Shape Memory Alloys (SMAs), is proposed to enhance the thermal and seismic behavior of steel tie-rods. First, the thermal behavior of steel tie-rods with and without SMAs is presented based on the results of extensive experimental tests in thermal room. Next, the seismic performances of the proposed SMA system are discussed based on the results of a series of shaking table tests on a 1:4-scale timber roof truss model. In this article, the functioning principles of the proposed SMA-based device prototype are illustrated and the main aspects related to its implementation in practice are discussed in detail. Finally, a recent example of application of the proposed technology to a historic single-aisle church, realized in the 13th century in Brindisi (southern Italy), and equipped with inadequate and deteriorated steel tied rods, is shown.

Causes and consequences of a construction disaster in a historic church

Paper concerns a construction disaster, which took place on June 4, 2018 in the 14th century St. George church in Hajduki Nyskie (Opole Voivodeship). The object is famous for its well-preserved 15th century wall polychromes. During the construction works, the eastern gable wall, part of the barrel vault with lunettes and part of the orchid roof truss collapsed at the roof truss. Some elements of the equipment were also destroyed. As a result of the catastrophe, valuable wall polychromes were directly threatened. Paper presents the causes and consequences of the catastrophe.

Design of one-storey industrial buildings from precast concrete

The widespread use of one-storey frame buildings and the absence of a normative document reflecting the specifics of designing precast concrete structures of these buildings necessitated the development of provisions for the design of the frame, as well as its individual structural elements such as foundations, foundation beams, columns, roof trusses, roof beams , slabs, crane girders and external enclosing structures. These provisions are reflected in the Code of rules 355.1325800.2017 "Frame constructions, prefabricated reinforced concrete, of one-storey industrial buildings. Design rules». The Code of rules developed by the authors' team of JSC TsNIIPromzdaniy consists of 7 sections and 4 annexes. There is a classification of buildings by space-planning solutions, equipment lifting and transport equipment, type of lighting, air exchange system and the presence of heating systems. The requirements of the Code of rules apply to the design of precast reinforced concrete frames of single-storey industrial buildings of mass use for all natural and climatic zones of the Russian Federation, except for sites with seismicity of 7 or more points and zones with permafrost. The considered document is intended for designers, developers of software systems, teachers, etc.

ROOF TRUSS DESIGN FOR INDUSTRIAL BUILDINGS

The roof trusses are mostly depended on the internal forces in the structure, dismember the structure and analyze separate free-body diagrams of individual members or combination of members. In this paper, the design of roof trusses frame, rivet diameters, and area of all members have to be calculated. General design theory of structural analysis, the equilibrium of rigid body, method of joints, tension and compression of members, mechanical properties of materials, design of riveted joints and area of trusses members in the project of Thilawa Zone (1) constructed by PREFAB STEEL Company Limited. This paper deals with the design and analysis of roof truss.

Operation Of Bracing System In The Roof Of Industrial Building With Steel Frame

Features of work of bracings in a covering of an industrial building with steel framework are considered. Horizontal bracings are designed to ensure the overall stability of the roof trusses, their unfastening from the plane of the frame, as well as for the perception of horizontal loads acting on the frame. At the traditional approach, depending on the type of bracing grid , they are designed as a compressed-stretched (triangular lattice), or as working only on the tension, in this case, the loss of stability of one of the bracing element (cross lattice) is allowed. This is a classic approach, which was used when calculating the structure considered flat frames, and the connections were designed for the action of horizontal loads (wind, crane). At present, with the development of computing software, it became possible to perform the calculation of the entire spatial framework of the building, making it possible to take into account the inclusion of the braces in the spatial work under the action of all types of loads. The results of analysis of the spatial framework of an existing industrial building are presented in the article. It is established that horizontal braces are included in the work also when vertical loads (dead load, snow, etc.) acting on the roof, as a result of which, even with a cross lattice, all braces can be compressed at the same time and lose stability, it is inadmissible and requires the implementation of the strengthening of the bracing system. Analysis of the possibility of taking into account the inclusion in spatial work of roof steel shields welded to the upper belt of trusses which to a certain extent unload horizontal braces is presented in the paper.

Overload in the roof trusses of the Media Center building in Saransk

The possibility of applying overload to the nodes of the bottom chord of the roof trusses of the Media Center building constructed as a part of the design of the temporary buildings and structures for the preparation and holding of the World Football Cup in the Russian Federation (Saransk) in 2018 is studied in the article. A variant of fixing the load with the help of the universal mounting is developed.

Hybrid Two-Stage Eagle Startegy for Reliability Analysis

Abstract In this paper, we devoted the reliability analysis by combining a two-stage eagle strategy (ES) with the first-order reliability method (FORM). In the first stage of ES, we use the so-called levy flights to improve the global search ability. In the second stage, we use a hybrid method based on the grey wolf optimizer (GWO) and accelarated particle swarm optimization (APSO) to intensify the local search. In the proposed method named as ES-GWPSO, FORM is used to evaluate the fitness of each agent. In order to investigate the efficiencies of ES-GWPSO in reliability analysis, four calssic examples, as well as a roof truss model are employed. The results are compared to four well-known heuristic algorithms. The results show that reliability analysis by using ES-GWPSO is significantly better than the current heuristic algorithms.

Ultrasonic evaluation regarding the effects of biological corrosion of historical roof trusses

For many years work has been performed to obtain sufficiently accurate correlation between the results of ultrasonic tests and the results of strength tests for evaluation of the strength parameters of wood in a structure. It is also important to ensure the development of methods which will facilitate the work of construction mycologists; that is, non-invasive methods of determining the volume of missing materials caused by biological corrosion. The study presents the idea of the objective examination of the thickness of a corroded layer by measuring the velocity of ultrasonic pulse along the fibre length using for this spot heads with thin waveguides. Another testing method presented in the study is controlling the velocity of ultrasonic wave in the direction tangential to annual growth rings by conducting tests on the corner of the corroded beam.

Equivalent stabilizing force of members parabolically compressed by longitudinally variable axial force

The EN 1993-1-1 model of equivalent stabilizing force qd and Rd of bracings conservatively assumes that the braced member is compressed with a force constant along its length. This assumption is incorrect since the axial force distribution varies along the length of the braced member. As a result, the braced member generates equivalent stabilizing forces different from equivalent force qd and Rd acc. to EN 1993-1-1. This paper presents parametric studies of the equivalent stabilizing forces of the braced, compression top chord of roof trusses. The girder’s top chord is compressed parabolically by a variable axial force. The values of the axial compressive forces is: Nsupp in the support zone of truss and Nspan in the central zone of truss. Parametric analyses of the equivalent stabilizing force and the stress of the purlins and the bracings depending on axial forces Nsupp and Nspan in the braced member were carried out. The investigated problem is illustrated with exemplary calculations of the equivalent force in trusses.

A Review and Development of Cold-formed Steel Channel Columns with Oriented Strand Board Sections

Abstract Cold-formed steel (CFS) is a steel-based material that is always used as a structural or non-structural component in construction activities. In Malaysia, CFS is broadly utilised in roof truss systems to replace timber and hot-rolled steel in residential houses and small industrial buildings. Some of the advantages of CFS include being lightweight, recyclable, and durable and having highest strength-to-weight ratio. It is also becoming excessively popular as a building material. However, CFS with its thin surface tends to fail in buckling on short and slender sections either at the compression or flexural members especially for the web element. In this study, the CFS channel section with 100 mm of the web, 50 mm of flange, 12 mm of lip, 1.55 mm of thickness and without any web stiffener has been selected. With the intention of solving the buckling failure, CFS has been formed as a symmetrical and closed section and filled with oriented strand board (OSB) at the gap of each section. The main objective of this study was to review the previous study of CFS with other materials to produce the composite material and introduce the development and preliminary study of the new section. The CFS with OSB was proposed as a solid symmetrical section to solve the local, distortional, and global buckling, as well as establish a stable and stiffened section under compressed conditions. Therefore, the local and distortional buckling of the compressed member was completely solved by the built-up and box-up of CFS with the OSB section however the CFS channel section with OSB managed to minimise the effect of local and distortional buckling. There was a 9.20%, 5.16% and 5.84% percentage difference of the ultimate load between the CFS without and with OSB sections. The new section reduced the production cost, while also reducing the material usage. It also has the potential to be an innovative section by supporting the Malaysian sustainable development programme.

Mechanical Behaviour for Connection of Cold-Formed Steel Channel Section with Intermediate Web Stiffener

Cold-formed steel (CFS) is a popular steel-based material for building such as roof truss system and wall frame panel. CFS with a variety of shapes, cross-sections and thickness produce a lot of advantages such as ease of production, corrosion resistance and high strength to weight ratio. Connection of the CFS sections between them uses screw, bolt and nut, rivet or weld. But, the detail information for the connector in standard either by Eurocode 3 or American Iron and Steel Institute (AISI) is still incomplete especially methods for testing and also lack in the basic knowledge of testing for the connector or combination of connectors. The connector that was used in this study was a self-drilling screw. The objective of the study is to provide the mechanical behaviour information of self-drilling screws from shear and pull-out tests. Both tests utilised Universal Testing Machine with 100 kN capacity to determine the ultimate load and load-deformation behaviour of the self-drilling screws with different numbers. As a result, the ultimate load of the specimen was found to increase with increasing number of the self-drilling screws for shear and pull-out connection tests.

Performance of a light timber‐framed compartment in natural fire subjected to lateral load

SummaryA common approach for designing buildings for lateral stability during and post‐fire in New Zealand is to ensure that a fire‐rated structure does not collapse when subjected to a nominal horizontal force. For external walls of residential buildings, which are required to resist a lateral load of 0.5 kPa, it is hypothesised that the adjacent unrated construction could provide sufficient support. A natural fire experiment has been conducted to evaluate the fire performance of a laterally loaded light timber‐framed compartment, with external dimensions of 4.33 m × 3.35 m and a stud height of 2.4 m constructed with a timber truss roof and plasterboard ceiling. During the experiment, the ceiling collapsed at 12 to 13 minutes, and the bottom chord of the roof truss failed in tension after 28 minutes which resulted in the fire‐rated wall losing its lateral stability at 28 minutes. The fire severity experienced in the compartment has been estimated to correspond to an equivalent time of 33‐minute exposure to a standard furnace time‐temperature. It is concluded that there is no need to provide nominal (additional) moment‐resisting fixity at the base of the fire‐rated wall when exposed to the standard fire for no more than 30 minutes.