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Vibration performance of a one-way simply supported timber-concrete composite (TCC) floor section has been studied using analytical as well as numerical methods. Focal points have been verification and validation of results from analytical and numerical calculations of vibration response based on experimental data. For the analytical calculations, floor bending stiffness and vibrational response are determined from methods proposed in the current and revised versions of Eurocode 5. The numerical calculations based on the finite element (FE) method are done using 3D solid elements with orthotropic material parameters. When comparing the results of the FE analysis, better agreement with the experimental data is reached for the fundamental frequency when 3D solid elements are used rather than 3D beam elements. Furthermore, better agreement with the experimental data is reached for RMS acceleration by FE analysis rather than the method based on Eurocode 5. For detailed analysis, the authors suggest performing dynamic FE analysis and calculating vibration response from the TCC floor's modal responses as eigenmodes and natural eigenfrequencies below 40 Hz. For future studies, it is recommended that the verification of vibration response may be accomplished by applying standard EN 16929.

This paper summarizes the findings of two full-scale blasts tests on a steel braced frame structure with composite floor slabs, which are representative of a typical office building. The aim of this research study was to experimentally characterize the behavior of conventionally designed steel braced frames to blast loads when enclosed with conventional and blast-resistant façade. The two tests involved a three-story, steel braced frame with concentrical steel braces, which are designed to resist typical gravity and wind loads without design provisions for blast or earthquake loads. During the first blast test, the structure was enclosed with a typical, non-blast-resistant, curtainwall façade, and the steel frame sustained minimal damage. For the second blast test, the structure was enclosed with a blast-resistant façade, which resulted in higher damage levels with some brace connections rupturing, but the building did not collapse. Observations from the test program indicate the appreciable reserved capacity of steel brace frame structures to resist blast loads.

A two-dimensional interface finite element capable of associating flat shell elements positioned one above the other was developed. The implemented interface element can physically simulate the contact between the flat shell elements and connect the reference planes of the shell elements above and below it. The formulation presented allows consideration of nonlinear behavior for the deformable connection as well as for the concrete and steel materials that make up the shell structure. One of the practical applications analyzed in this research is the numerical simulation of composite floors formed by a reinforced concrete slab connected to steel beams through a deformable connection. In this case, the concrete slab and the steel beams are discretized by flat shell elements and the deformable connection is discretized by two-dimensional interface elements. Experimental and numerical results from literature were used to validate the implemented elements. In the two examples analyzed, the results obtained for the displacements were close, with the difference, in the first case, being associated with uncertainties during the experimental test and in the second, the difference in theories used in the formulation of the implemented elements.

Desert sand foamed concrete (DSFC), which offers advantages, such as fire resistance, sound insulation, construction convenience, and environmental benefits, has not been used in cold-formed steel (CFS) composite floors. In this study, four full-scale specimens were designed and tested under four-point bending to investigate the effect of foamed concrete filling and holes. The load–deflection curves and strain distribution at mid-span were measured and analyzed. The experimental results indicated that the failure modes of the CFS composite floors were local buckling at the top flange for specimens without holes and tensile failure at the bottom flange for specimens with holes, respectively, which differed from the web crippling observed in non-composite floors. Moreover, due to the presence of foamed concrete, the flexural stiffness was significantly improved by 117.6% and 73.6% for the specimens without holes and with holes, respectively, while ultimate capacity increased by 224.9% and 121.8%, respectively. Through the nonlinear finite element models validated against experimental results, it was found that the flexural behavior was improved with the increase in CFS thickness and foamed concrete strength. The impact of the holes was not obvious for specimens infilled with holes.

Innerhalb dieser Diplomarbeit werden Holz-Faserbeton-Verbunddecken n��her untersucht. Dabei liegt der Fokus sowohl auf der Bemessung von Holz-Faserbeton-Verbunddecken als auch auf der Untersuchung von Faserbeton als Teil der Verbunddecke. Durch diese Betrachtungen soll aufgezeigt werden, ob Faserbeton eine wirtschaftliche Alternative zu normal bewehrtem Beton in Holz-Beton-Verbunddecken sein kann. Neben dieser Fragestellung wird weiters nach dem Unterschied in der Bemessung von Holz-Faserbeton-Verbunddecken in ��sterreich und Deutschland gefragt. Aus diesem Grund werden die Grundlagen f��r die Berechnungen ausgearbeitet und f��r ��sterreich und Deutschland verglichen. Bei der Berechnung von Holz-Beton-Verbunddecken mit Hilfe des ��-Verfahrens erfolgt, anhand der Einwirkungen auf den Gesamtquerschnitt, eine Aufteilung der Schnittgr����en auf die einzelnen Querschnittsteile. Danach werden die Nachweise an den Einzelquerschnitten gef��hrt. F��r den Holzquerschnitt und die Verbindungsmittel regelt die EN 1995-1-1 [1] die Nachweisf��hrungen im Hochbau, diese unterscheiden sich maximal durch den nationalen Anhang. Hingegen ist die Anwendung von Faserbeton in Normen nicht geregelt. Allerdings existieren Richtlinien f��r die Bemessung von Faserbeton. In Deutschland ist dies die vom deutschen Ausschuss f��r Stahlbeton herausgegebene Richtlinie ���Stahlfaserbeton��� [2] und in ��sterreich von der ��sterreichischen Bautechnik Vereinigung herausgebrachte Richtlinie ���Faserbeton��� [3]. Daher werden die Unterschiede der Richtlinien dargestellt und in weiterer Folge die Auswirkungen in der Bemessung von Holz-Faserbeton-Verbunddecken aufgezeigt.Ziel dieser Arbeit ist es, die Vor- und Nachteile von Holz-Faserbeton-Verbunddecken aufzuzeigen und damit einen wirtschaftlichen Einsatz zu erm��glichen. Au��erdem soll ein Zusammenhang der beiden Richtlinien in Bezug auf Verbunddecken erstellt werden, um f��r den Einsatz von Faserbeton in unterschiedlichen L��ndern, keine zus��tzlichen Pr��fungen f��r die Klassifizierung durchf��hren zu m��ssen.In einem ersten Schritt wird der Faserbeton selbst n��her beschrieben, dabei wird auf die unterschiedlichsten Arten von Fasern und das Tragverhalten allgemein eingegangen. Dies stellt den Stand der Technik dar und beschreibt die Eigenschaften von Faserbeton. Im zweiten Schritt werden die beiden Richtlinien aus Deutschland und ��sterreich beschrieben und miteinander verglichen. Hier ist ersichtlich, dass es unterschiedliche Versuchsaufbauten, Klasseneinteilungen und Berechnungsmethoden gibt. Um diese Unterschiede aufzuzeigen, wurden in einem weiteren Schritt experimentelle Untersuchungen mit einem einheitlichen Stahlfaserbeton durchgef��hrt. Insgesamt 24 Probek��rper in Form von Balken wurden anhand von 4-Punkt-Biegeversuchen gepr��ft und nach der jeweiligen Richtlinie ausgewertet. Dabei gibt es sowohl Unterschiede bei der ��quivalenten Biegezugfestigkeit als auch bei den Bemessungswerten der Nachrisszugfestigkeit. Bei den Bemessungswerten wurden zum Teil gro��e Unterschiede festgestellt, obwohl es sich um den gleichen Faserbeton handelt. In einem weiteren Schritt wurde danach ��berpr��ft, wie sich diese Differenzen beim Faserbeton auf die Bemessung der Holz-Faserbeton-Verbunddecke auswirken. Anhand von Berechnungen stellte sich heraus, dass die vorher gro��en Unterschiede der Nachrisszugfestigkeiten wenig Einfluss auf die Tragf��higkeit von Holz-Faserbeton-Verbunddecken haben. Zuletzt wurden f��r eine Betrachtung der Wirtschaftlichkeit, Vergleiche zwischen Holz-Beton-Verbunddecken mit Stahlfasern und mit herk��mmlicher Bewehrung durchgef��hrt. Dabei zeigte sich, dass bei Faserbeton die erforderliche Anzahl an Verbindungsmittel gr����er ist. Allerdings spielt hierbei insbesondere die Dicke der Faserbetonschicht, die Spannweite der Decke und die tats��chliche Auflast eine gro��e Rolle. Beim Einsatz von Stahlfaserbeton ist somit keine zus��tzliche Bewehrungsverlegung, allerdings eine gr����ere Verbindungsmittelzahl notwendig. Holz-Faserbeton-Verbunddecken stellen daher vor allem bei Bauen im Bestand eine Alternative zu konventionellem Beton mit Bewehrung dar., Within this diploma thesis, timber-fiber concrete-composite floors are investigated in more detail. The focus is on the design of timber-fiber concrete-composite floors as well as on the investigation of fiber-reinforced concrete as part of the composite floor. These considerations are intended to show whether fiber-reinforced concrete can be an economical alternative to normally reinforced concrete in timber-fiber concrete-composite floors. In addition to this question, the difference in the design of timber-fiber concrete-composite floors in Austria and Germany will also be investigated. For this reason, the basics for the calculations are elaborated and compared for Austria and Germany. In the calculation of timber-fiber concrete-composite floors especially with the ��-method, the forces are distributed to the individual cross-section parts on the basis of the influence on the total cross-section. Afterwards, the verifications are carried out on the individual cross-sections. For the timber cross-section and the connecting elements, EN 1995-1-1 [1] regulates the verification procedures in building constructions, which differ at most by the national annex. Fiber-reinforced concrete, on the other hand, is not regulated in the Eurocode. However, there are guidelines for the design of fiber-reinforced concrete. In Germany, this is the guideline "Steel Fiber Concrete" [2] published by the German Committee for Reinforced Concrete, and in Austria, the guideline "Fiber Concrete" [3] published by the Austrian ���Bautechnik Vereinigung���. Therefore, the differences between the guidelines are presented and subsequently the effects in the design of timber-fiber concrete-composite floors are shown.The aim of this thesis is to work out the advantages and disadvantages of timber-fiber concrete-composite floors to enable their economic use. In addition, a correlation of the two guidelines in relation to composite floors is to be established, in order to avoid additional tests for the classification for the use of fiber-reinforced concrete in different countries.In a first step, the fiber-reinforced concrete itself will be described in more detail, including the various types of fibers and the load-bearing behavior in general. This represents the state of the art and shows charcteristics of fiber-reinforced concrete. In the second step, the two guidelines from Germany and Austria are described and compared. Here it is evident that there are different test setups, classifications and calculation methods. In order to highlight these differences, experimental tests were carried out with a uniform steel fiber concrete in a further step. A total of 24 beams were tested using 4-point bending tests and evaluated according to the respective guideline. There are differences in the equivalent flexural strength as well as in the design values of the post-cracking tensile strength. In some cases, big differences were found in the design values, although the same fiber-reinforced concrete was used. In a further step, it was then examined how these differences in the fiber-reinforced concrete affect the dimensioning of timber-fiber concrete-composite floors. Based on calculations, it was found that the previously large differences in post-cracking tensile strenghts have little influence on the load bearing capacity of timber-fiber concrete-composite floors. Finally, for a consideration of the economic efficiency, comparisons were made between composite ceilings with steel fiber concrete and with conventional reinforcement. This showed that the required number of connection elements is higher for fiber-reinforced concrete. However, the thickness of the fiber-reinforced concrete layer, the span oft the ceiling and the actual load play a major role here. Thus, when using steel fiber reinforced concrete, no additional reinforcement laying is required, but a larger number of connection elements is necessary. Timber-fiber concrete-composite floors are an alternative to reinforced concrete, especially for constructions in existing buildings.

This study aims to present a multi-criteria decision analysis (MCDA) for comprehensive performance evaluation of the alternative design of timber–concrete composite (TCC) floor system. Considered objectives are serviceability and sustainability performance with associated criterion as (1) comfort class regarding springiness and vibrations, (2) architectural quality with associated criterion as open spaces, (3) environmental aspect with associated criterion as CO2 emissions and (4) cost aspect with associated criterion as the total costs. Analytical Hierarchy Process (AHP) and Complex Proportional Assessment (COPRAS) as the methods in the multi-criteria analysis have been combined for (1) determining the weighting of criteria based on the survey results, (2) verifying the consistency ratio of decision matrix made by experts and (3) for ranking and selecting the optimal concept design among design candidates. According to the results, the TCC floor with the span length of 7.3 m belonging to comfort class A has got the highest ranking. However, sensitivity analysis indicates that the TCC floor with a 9.0 m span length belonging to comfort class A shall be selected as the optimal concept design. The study contributes by developing a complete concept design tool for TCC floor systems using AHP combined COPRAS methods to handle both beneficial and non-beneficial criteria.

Työn tavoitteena on laatia ohjeet CLT–betoni-liittorakenteisten laattojen rakennemitoitukseen sekä voimassa olevat että tulevat Eurokoodit huomioiden. Ohje on erityisesti tarkoitettu käytettäväksi vanhojen Eurokoodien voimassa ollessa, mutta sitä voi käyttää viitteellisenä ohjeena myös Eurokoodien päivittyessä. Tällöin suunnittelijan on kuitenkin varmistettava kaavojen ja ohjeiden pätevyys, sillä ne ovat saattaneet päivittyä. Myös CLT- ja liitostoimittajien tuotekohtaisten teknisten standardien voimassaolo pitää tarkastaa. Työssä on esitetty laatan kuormitukset ja kuormitusyhdistelmät nykyisten Eurokoodien EN 1990 ja EN 1991 mukaan. Kuormien ja yhdistelmien arvoissa ja kaavoissa on kerrottu Eurokoodin suositusarvot sekä Suomen kansallisten liitteiden arvot ja valinnat. Lisäksi on esitetty betonin ja CLT:n kutistumien ja lämpö- sekä kosteusliikkeiden kaavat sekä näistä aiheutuvien rasitusten laskentakaavat. Käytännössä usein ainoa huomioitava liike on betonin kuivumiskutistuma, joka aiheuttaa jopa 30–50 % lopputaipumasta. Viruman vaikutus jännityksiin ja taivutusjäykkyyteen on huomioitu käyttämällä pitkäaikaisten kuormien osuudelle jäykkyysominaisuuksien tehollisia arvoja. Betoni viruu puu–betoni-liittorakenteessa enemmän kuin normaalissa teräsbetonirakenteessa. Sen lopullisen kimmokertoimen arvo viruville kuormille saattaa olla vain 20 % alkuperäisestä. Betonin viruman ja kutistuman rajoittamisella olisi suuri merkitys poikkileikkaukselle varsinkin suurilla jänneväleillä. Poikkileikkauksen taivutusjäykkyyden laskennassa on huomioitava leikkausliitoksen ja poikittaislamellien leikkausmuodonmuutos. Tässä työssä se on tehty laajennetulla gamma-menetelmällä. Menetelmä osoittautui soveltuvan erinomaisesti monikerroksisille liittolaatoille. Työssä on esitelty CLT:n ja betonin välisten leikkausliitosten mitoitustapoja teknisten hyväksyntöjen sekä uusien Eurokoodien luonnosten mukaan. Nykyisen EN 1995 tai sen Suomen kansallisen liitteen mukaiset värähtelymitoitusohjeet eivät sovellu matalataajuuslattioille, jollaisia CLT–betoni-liittolaatat usein ovat, joten työssä on esitelty myös uuden EN 1995 luonnoksen mukainen värähtelymitoitus. Murtorajatilan mitoitus on esitetty tapauskohtaisesti nykyisen tai tulevan Eurokoodin luonnoksen mukaan. CLT:n palomitoitus on esitetty valmistajien sekä tulevan Eurokoodin luonnoksen mukaan huomioiden CLT:n lamellien mahdollinen delaminoituminen. Tyypillisesti laatan mitoittaa lopputaipuma. Tämän takia tutkittiin erityisesti liittolaatan sekä kimmoiseen että lopulliseen taivutusjäykkyyteen vaikuttavia tekijöitä. Tutkimuksessa havaittiin, että tyypillisesti selvästi jäykimpään liittopoikkileikkaukseen päästään CLT-levyllä, jonka alimmainen kantava kerros on paksu ja jossa on pinta-alaltaan paljon kantavaa lamellia. Tämä voidaan saavuttaa esim. liimaamalla samansuuntaisia lamelleja päällekkäin uloimpiin kerroksiin. Loviliitos on tyypillisesti jäykin tutkituista leikkausliitoksista. Myös erilaisten valutuentojen vaikutuksia tutkittiin. Tutkimuksen perusteella esitettiin eri jänneväleille esimerkkirakenteet. Liitteessä A on tutkitun esimerkkirakenteen laskelmaraportti, joka on toteutettu työn ohessa tehdyllä Excel-mitoituspohjalla. The purpose of this thesis is to establish a guideline for dimensioning CLT–concrete floors, while considering both the existing and upcoming Eurocodes. The guideline is specifically meant to be used with existing Eurocodes, but it can be used as a reference later. However, the designer must ensure that they follow the new Eurocodes, as the formulae and instructions may have been updated. Also, the latest technical documents and approvals must be used. The loads and load combinations have been presented according to existing Eurocodes EN 1990 and EN 1991. Both recommended and national Finnish values and choices are given. A method is presented to calculate the effects of inelastic strains, such as concrete shrinkage, which is usually the most significant by far, causing up to 50 % of the final deflection. The effects of creep are considered by using effective stiffness properties of timber, concrete and shear connectors for quasi-permanent loads. Concrete has higher creep in timber–concrete structures than in reinforced concrete structures. Its final effective modulus of elasticity may be as low as 20 % of its original value. The rolling shear deformation and the slip of shear connectors must be considered when calculating bending stiffness. This is done here with the extended Gamma method, which applies well with multi-layer composite slabs. This study presents different shear connectors and their dimensioning according to their European approvals or the upcoming Eurocodes. The current EN 1995 or its Finnish national annex’s vibration analysis don’t apply to low-frequency floors, which is often the case for CLT-concrete floors. This study suggests using the vibration analysis of the upcoming EN 1995 even before its passage. Calculation of the charring of CLT is presented according to existing guidelines from manufacturers and the upcoming Eurocode EN 1995-1-2, which takes possible delamination into account. Usually the final deflection was found to be the most demanding criterion for the slab. Therefore, the elastic and final bending stiffnesses and their factors were studied. It was found that CLT elements with thick bottom layers and small transverse layers were usually the stiffest choice by far. The notched connection was usually the stiffest out of the studied connections. The effects of propping were also studied. A list of example structures with different spans was made. A calculation report of an example structure that was studied is found in appendix A. The report was made with an Excel-based calculation tool that was developed during this thesis.

This paper proposes a novel multi-cavity steel&ndash, concrete composite floor. The mechanical properties of multi-cavity steel&ndash, concrete composite floor were studied by static load test. Based on full-scale tests on 2500 &times, 1000 &times, 120 mm multi-cavity steel&ndash, concrete composite floors, the bearing capacity and failure characteristics of the composite floor were analyzed. Compared with the existing prefabricated floor, the reliability of the test was verified by finite element simulation. The influence of steel plate material thickness, floor thickness, cavity size and span on the mechanical properties of composite floor was analyzed. The results showed that the composite floor had stronger bearing capacity and better ductility and integrity than the existing precast floor. The bearing capacity and stiffness of composite floor were positively correlated with the thickness of steel plate and floor, and negatively correlated with the cavity size and span.

U ovome radu biti će riječ o numeričkoj analizi udara konstrukcije poda helikoptera u tlo u programskom paketu Abaqus/Explicit s ciljem određivanja opterećenja kojima je u tom slučaju izložena posada. Modeliran je jednodijelni aluminijski model koji je validiran podacima iz literature gdje je eksperimentalno ispitan dio konstrukcije poda helikoptera Westland WG30 u kojem je smještena posada. Zatim su kritični dijelovi konstrukcije modelirani detaljno, zakovičnim spojem, te se na tom modelu također vrši validacija. U sljedećem poglavlju vrši se izrada numeričkog modela kompozitne podnice helikoptera na dva načina – kao monolitnu i kao sandwich konstrukciju uzimajući u obzir svojstva materijala koji se koriste u tu svrhu u realnim konstrukcijama. Podnica je opterećena prvo krutom pločom kako bi simulacija pratila eksperiment, zatim konstrukcijom sjedala i masom posade. Analiza konstrukcijom sjedala vršena je na dvije monolitne podnice različitih orijentacija te sandwich podnici helikoptera koje su međusobno uspoređene kako bi se odredio utjecaj izvedbe podnice na opterećenja posade helikoptera. Na kraju se proučava utjecaj debljine jezgre sandwich kompozitne podnice helikoptera. The aim of this study is to perform a numerical analysis of the impact of a helicopter floor structure on the ground in the Abaqus/Explicit software package to determine the loads to which the crew is exposed. A one-piece aluminum model has been modeled that has been validated using experimental data from the available literature. The part of the floor structure containing the crew of the Westland WG30 helicopter has been tested in this experiment. Then, the critical parts of the structure are modeled in detail, with a rivet joint, and validation is also performed on that model. In the next section, the numerical model of a composite helicopter floor is made in two ways - as a monolithic and as a sandwich structure, considering the properties of the materials used for this purpose in real structures. The floor was first loaded with a rigid plate for the simulation to follow the experiment, then with seat structure and crew mass. The seat structure analysis was performed on two monolithic floors of different ply layups and a helicopter sandwich floor. The results of these analyses were compared to each other to determine the impact of the floor design on helicopter crew loads. Finally, the effect of the core thickness of the sandwich composite helicopter floor is studied.

Background: The performances of composite steel-concrete slabs are strongly influenced by the connection between the concrete and the steel decking, which is essentially assured by bonding, interlocking, and adhesion. The connection can be continuous or localized by means of connectors. In order to increase the bonding between steel and concrete elements and to allow their collaboration, typically, a continuous connection with indentations or embossings is realized. Objective: In this study, the simulation of the concrete-steel bond interaction of a typical composite decking is analyzed. In particular, the objective is the investigation of the role of the main geometric parameters of the indentations or embossings that determine the effective functionality of the connection. Methods: To this scope, the results of four-point bending tests on five specimens of a typical layout of a composite floor are reported and discussed. Then, the obtained results are used to determine the shear bond strength according to the partial interaction method, by following the procedure provided by the Eurocode 4. Successively, the experimental results are exploited in order to calibrate a FE model in Abaqus software to be able to account for the basic effects involved in the shear bonding mechanism, i.e. interlocking, friction, and adhesion. Results & Conclusion: Finally, the obtained results are discussed, and the FE model is used to evaluate the geometrical and mechanical parameters influencing the longitudinal shear bonding resistance.

The present paper deals with composite steel-concrete floor with headed shear studs welded onto a flat steel plate. In bridges applications, which are the focus of the paper, very thick steel plates are often combined with a moderate layer of concrete. And, in some wide slab applications, the most performant lay-out for the shear studs could lead to them being welded on top of an existing butt weld between steel plates. Presently, we are ignorant about the shear resistance of the weld-to-weld interface and its possible detrimental effect on the overall resistance of the system. In addition, the ultimate behaviour of the system combines the flexural resistance of a composite cross-section followed by, when the concrete is cracked, the development of a compressed arch anchored in these headed shear studs, emphasising the importance of such connections. Both questions are addressed in the paper and, based on experiments, an in-depth analysis on the system’s behaviour at ultimate limit state is provided. Two types of tests are performed: pure shear tests complying to the push-out tests of Annex B of EN 1994-1-1 and beam tests with four-point loading where the studs in the shear spans are loaded with longitudinal shear. For each pair of tests, the reference specimen was made with a steel plate without a butt weld or comprising a butt weld directly under the line of shear studs. Typical floor dimensions from bridge applications are studied. No difference in shear capacity, stiffness or failure mode could be observed. However, it was noticed that the classic design rules provided in EN1994-1-1 cannot accurately predict the failure load of the chosen configuration. Based on assumptions made following the observations of the failure mechanisms, the authors propose a theoretical evaluation of the capacity of the system. ispartof: Engineering Structures vol:197 status: published

Purpose This paper aims to investigate computationally and analytically how different levels of restraint from surrounding structure, via catenary action in beams, affect the survival of steel framed structures in fire. This study focuses on examining the mid-span deflection and the tensile axial force of a non-composite heated steel beam at large deflection that is induced by the catenary action during exposure to fires. The study also considers the effect of the axial horizontal restraints, load-ratio, beam temperature gradient and the span/depth ratio. It was found that these factors influence the heated steel beam within steel construction and its catenary action at large deflection. The study suggests that this may help the beam to hang to the surrounding cold structure and delay the run-away deflection when the tensile axial force of the beam has been overcome. Design/methodology/approach This paper is part one of the parametric study and discusses both the effect of the axial horizontal restraints and load-ratio on the heated steel-beam. Reliance on the prescriptive standard fire solutions may lead to an unpredicted behaviour of the structure members if the impact of potential real fires is not considered. Findings Variation of the horizontal end-restraint level has a major effect on the behaviour of the beam at high deflection, and the loading on a beam at large displacement can be carried effectively by catenary behaviour. An increase of axial horizontal stiffness helps the catenary action to prevent run-away at lower deflections. The studies also investigated the influence of varying the load ratio on the behaviour of the heated beam at large deflection and how it affects the efficacy of the catenary action. The study suggests that care should be taken when selecting the load ratio to be used in the design. Originality/value In a recent work, the large deflection behaviours of axially restrained corrugated web steel beam (CWSB) at elevated temperatures were investigated using a finite element method (Wang et al., 2014). Parameters that greatly affected behaviours of CWSB at elevated temperatures were the load ratio, the axial restraint stiffness ratio and the span–depth ratio. Other works included numerical studies on large deflection behaviours of restrained castellated steel beams in a fire where the impact of the catenary action is considered (Wang, 2002). The impact of the induced axial forces in the steel beam during cooling stage of a fire when the beam temperature decreases, if thermal shortening of the beam is restrained, large tensile forces may be induced in the beam (Wang, 2005; Allam et al., 2002). A performance-based approach is developed for assessing the fire resistance of restrained beams. The approach is based on equilibrium and compatibility principles, takes into consideration the influence of many factors, including fire scenario, end restraints, thermal gradient, load level and failure criteria, in evaluating fire resistance (Dwaikat and Kodur, 2011; Allam et al., 1998).

This paper presents parametric studies on three-dimensional steel-frame-composite-floor systems (3D composite floor systems) subjected to column loss using macro-based finite element (FE) models and a verified analytical method. The FE modelling method is verified by four actual experimental tests with three important variables, viz. slab aspect ratio, boundary condition and degree of composite action between composite slabs and steel beams. To overcome the shortage of data acquisition in the actual composite floor system tests, the FE models can be used to investigate the effects of these variables on load-resisting mechanisms, such as flexure and catenary action in the double-span girder and the double-span beam over the missing column, and flexure and tensile membrane action in composite slabs. In addition, the parametric studies are extended to include slab thickness. In a similar manner, the analytical model is used to study the effects of slab aspect ratio and joint type on robustness of 3D composite floor systems. After evaluating the robustness of eight sub-structures with different combinations of extended-end-plate, flush-end-plate, web-cleat and fin-plate joints, a few combinations are recommended. Lastly, consistency between FE simulations and the analytical predictions is confirmed through a comparison of energy stored in different structural members. Ministry of Home Affairs The authors would like to gratefully acknowledge the financial support provided by the Ministry of Home Affairs in Singapore.

The purpose of this article is to provide an insight into the field of timber floor strengthening with cross-laminated timber (CLT) panels. A classic timber floor strengthened with CLT panels is therefore analysed according to the current building standards in the European Union, the Eurocodes. Seven different CLT panels, with thicknesses from 60 mm to 120 mm, are taken into consideration for the numerical study. Self-tapping screws with a diameter of 6 mm and length of 200 mm are used as shear connectors. The gamma method is used for calculating the effective bending stiffness. The design procedure is briefly presented, and the results for different configurations are compared., Cilj je ovog rada pokazati kako ojačati podne konstrukcije koristeći unakrsno laminirane drvene panele (CLT paneli). Kao predmet studije uzete su klasične drvene podne konstrukcije ojačane sa CLT panelima i uspoređene s Eurocode standardima, službenim graditeljskim standardom u EU-u. Sedam različitih tipova panela debljine od 60 do 120 mm su analizirani u numeričkoj studiji. Kao sredstvo sprezanja uzeti su samourezujući vijci promjera 6 mm i duljine 200 mm. Za proračun efektivne savojne krutosti korištena je gama metoda. U radu je kratko prikazana procedura dimenzioniranja te su uspoređeni rezultati različitih konfiguracija podnih konstrukcija.

One of the most destructive natural phenomena is the earthquake. These events destroy lives, goods and disrupt human activities. For this reason the anti-seismic protection of buildings is a very important and of interest subject in Civil Engineering. In the case of structures with a low seismic energy dissipation capacity (for example steel frame structures with Slimdek composite floors), this problem becomes more complicated due to the requirement of dampers. In this paper an experimental study is presented regarding an innovative yielding metallic energy dissipation device, proposed by the author. An experiment is carried out on a shake table. By studying the results from the experiments and from the previous carried out numerical analysis we can conclude that this device provides a high anti-seismic protection for this type of structures.

International audience; Horizontal stability of the medium rise steel frame structures is usually ensured by vertical bracings and diaphragm action of composite floors. Load transfer within the composite floor system is made through shear connectors, e.g. headed studs. In an event of explosion, such connectors must reserve sufficient residual stiffness and strength in order to avoid a sudden or delayed collapse of the building. These remaining capacities have not been experimentally studied yet in the literature. This paper presents large scale horizontal push out tests to determine the residual stiffness of the shear connectors after being initially damaged by explosion. The initial damaging is reproduced by a pull-out test using a quasi-static loading. Two types of numerical simulation have also been developed using ABAQUS/CAE software to provide a better understanding of the experimental results.

Denna rapport utreder möjligheterna att använda restprodukter som ljudisolering i lägenhetsskiljande mellanbjälklag av trä med spännvidd 6 m. Ett steg mot att uppfylla Sveriges byggindustris nollvision för koldioxidutsläpp är att bygga mer i trä och att återanvända/återvinna restprodukter. Det svenska entreprenadföretaget Skanska har vid sina krossanläggningar ett överskott av material i form av bergkross 0 - 0,2 mm och krossad restbetong. I denna rapport har en prototyp av ett träbjälklag tagits fram med influenser från byggtekniken från sekelskiftet 1800–1900 med avseende på nyttjandet av tung fyllningsmassa som ljudisolering i träbjälklag. Den framtagna bjälklagsprototypen uppfyller de krav som ställts i BBR efter dimensionering enligt Eurokoderna med hänsyn till brand, hållfasthet, svikt och nedböjning. Enligt en simulering i SEAWood, ett verktyg för akustiksimulering som är under utveckling vid RISE Research Institutes of Sweden, uppfylls även kraven på ljudisolering, detta stöds av de analyser som gjorts av mätresultat från liknande bjälklag. Fyllningsmaterialets höga vikt medför att prototypen är ett lågfrekvent bjälklag, detta kombinerat med att simuleringen endast är en indikation på ljudisoleringsegenskaper gör att det kommer krävas praktiska tester för att fastställa prototypens ljudisolerande och dynamiska egenskaper. Den framtagna bjälklagsprototypen är lämplig att prefabricera tack vare en konstruktion med få ingående delar. Att prefabricera bjälklaget har utöver de ekonomiska fördelar det medför stora fördelar ur ett arbetsmiljöperspektiv och är även fördelaktigt ur fuktsynpunkt. För att uppskatta bjälklagets miljöpåverkan gjordes en enklare jämförelse med ett prefabricerat betongbjälklag som visade att utsläppen av koldioxidekvivalenter fram till bruksfasen var mer än dubbelt så stor för betongbjälklaget än för prototypbjälklaget. This report investigates the possibilities of using residual products as sound insulation in apartment separating timber floors with a span of 6 m. One step towards meeting the Swedish construction industry's zero vision for carbon dioxide emissions is to build more using timber and to reuse/recycle residual products. The Swedish building contractor Skanska has at its quarries a surplus of material in the form of crushed rock of the 0 - 0.2 mm fraction and crushed residual concrete. In this report, a prototype of a timber floor has been produced with influences of construction technology from the turn of the 19 th century regarding the use of heavy filling as sound insulation in timber floors. The developed floor prototype complies with the requirements set in BBR after dimensioning according the Eurocodes regarding fire safety, strength, sagging and deflection. According to a simulation in SEAWood, a tool for acoustic simulation which is under development at RISE Research Institutes of Sweden the requirements for sound insulation are also met, which is supported by analyzes made by comparing with data on similar timber floors. The high mass of the filling material implies that the prototype is a low frequency floor, this in conjunction with the simulation only being an indication of sound insulation properties, it will require practical tests to determine the prototypes sound insulating and dynamic properties. The developed floor prototype is suitable for prefabrication thanks to a design with few components. Prefabrication of the floor has in addition to the economic benefits it brings great benefits from a working environment perspective and is also beneficial from a moisture point of view. To estimate the environmental impact of the timber flooring, a simple comparison was made with a prefabricated concrete floor which showed that carbon dioxide emissions up to the using phase were more than twice that of the concrete floor than for the prototype floor.

Connecting timber panels to steel girders using mechanical fasteners (e.g. screws and bolts) is an attractive and novel method for developing a fully prefabricated and sustainable hybrid steel-timber composite (STC) floor that can also facilitate future dismantling and recycling of the structural components. This study concerns the short-term behaviour of innovative STC floors comprising of cross-laminated timber (CLT) and/or laminated veneer lumber (LVL) panels connected to steel girders by various mechanical fasteners and/or glue. The mechanical characteristics of STC connections play an essential role in the safe and economical design of hybrid STC structures and floor systems. Accordingly, at the first stage of this research project, short-term behaviour of STC connections has been investigated. Push-out tests on different types of STC lap joints with coach screws (with and without a reinforcing nail plate), high-strength bolts and a combination of glued and screwed connectors are reported, and the load-slip behaviour, stiffness, strength and failure modes of the STC connections are characterised. At the second stage, short term behaviour of STC system was investigated through four-point bending tests. The results of four-point bending tests performed on full-scale STC beams are reported and the structural behaviour (i.e. the load-deflection response, short-term stiffness, and peak load capacity and failure modes) of the proposed STC system are studied. At the last stage of the project, extensive non-linear 1D and 2D finite element (FE) analyses of STC beams are carried out and the numerical results are verified against the test results. It is shown that 1D and 2D FE models can adequately capture the structural response of the STC beams. Using the FE and experimental results, the composite efficiency of STC beams that can significantly influence their structural behaviour beams is determined. In addition, the mechanical behaviour of lap STC connections was investigated through using a nonlinear 3D continuum-based FE model. In the FE models developed, the non-linear behaviour and failure of the timber is captured by a stress-based failure criterion formulated in the framework of continuum-damage mechanics. Yielding of the steel plates and fasteners (i.e. coach screws and bolts) is captured by an elastic-hardening plastic constitutive law. These FE models are validated against experimental (push-out) tests conducted on LVL and Steel-CLT composite lap connections. It is shown that the FE models developed can adequately predict the load-slip response and failure mode of the hybrid steel-timber composite connections tested. The validated FE model is used to undertake a parametric study that elucidates the influence of the yield strength and the length of the fasteners and the post-tensioning force in the bolts on the stiffness, load carrying capacity and load-slip behaviour of hybrid steel-timber composite connections.

According to full-scale fire tests, it is noticed that tensile membrane action within the concrete floor slabs plays an important role in affecting the fire resistance of composite buildings. It is well known that the development of tensile membrane actions relies on the vertical support along the edges of the slab panel. However, there is at present a lack of research into the influence of vertical supports on the tensile membrane actions of the floor slabs. In this paper, the performances of a generic three dimensional 45 m×45 m composite floor subjected to ISO834 Fire and Natural Fire are investigated. Different vertical support conditions and three steel meshes are applied in order to assess the impact of vertical supports on tensile membrane action of floor slabs. Unlike other existing large scale modelling which assumes the connections behave as pinned or rigid for simplicity, two robust 2-node connection element models developed by the authors are used to model the behaviour of end-plate and partial end-plate connections of composite structures under fire conditions. The impact of connections on the 3D behaviour of composite floor is taken into consideration. The load-transfer mechanisms of composite floor when connections fail due to axial tension, vertical shear and bending are investigated. Based on the results obtained, some design recommendations are proposed to enhance the fire resistance of composite buildings.

A crescente competitividade do mercado da engenharia civil tem induzido projetistas de estruturas a desenvolverem sistemas estruturais compostos por peças mais leves e com menor custo final. A conseqüência direta dessa filosofia de projeto foi o aumento considerável dos problemas de vibrações em pisos. Assim sendo, o principal objetivo desse trabalho é o de desenvolver uma metodologia de análise para avaliação do conforto humano em pisos de edificações, com base em modelos de carregamento representativos do caminhar das pessoas. Os modelos estruturais foram compostos por pisos mistos com vão variando de 5,0m a 10,0m. Um estudo paramétrico extenso foi desenvolvido e os resultados, com base nos valores das acelerações de pico, foram comparados com valores-limites propostos por diversos autores e normas de projeto. Os resultados encontrados indicaram que a ação do caminhar das pessoas pode vir a gerar níveis elevados de vibração sobre os pisos, não satisfazendo os critérios de conforto humano. The competitive trends of the civil engineering market have long been forcing structural engineers to develop minimum weight and labor cost solutions. A direct consequence of this new design trend is a considerable increase in floor vibration problems. The main objective of this paper is to present an analysis methodology to evaluate the composite floor's human comfort criteria, considering a more realistic loading model incorporating the dynamic effects induced by people walking. The investigated models were based on floors, with main spans varying from 5m to 10m. Based on an extensive parametric study the composite floors dynamic response was obtained and compared to limiting values proposed by several authors and design standards. The results of the present study indicated that the walking loads could induce the composite floors to reach significant vibration levels implying and violating the human comfort criteria.

Submitted by Boris Flegr (boris@uerj.br) on 2021-01-06T19:00:41Z No. of bitstreams: 1 DissertacaoAntonio Vicente.pdf: 2341625 bytes, checksum: d1883dead1e8d42a6978316335abe7bb (MD5) Made available in DSpace on 2021-01-06T19:00:41Z (GMT). No. of bitstreams: 1 DissertacaoAntonio Vicente.pdf: 2341625 bytes, checksum: d1883dead1e8d42a6978316335abe7bb (MD5) Previous issue date: 2005-07-15 Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro Nowadays, the new architectural tendency and the market requirements, are leading structural engineering in the search for bolder solutions, which demands great experience and knowledge of the structural designers associated to the use of new materials and technologies. This philosophy of structural conception is inserted in one of the most important trends of project of the last years that means: the search for structural systems of fast execution, endowed with parts of lower weight and that can be successfully large with a minimum of vertical elements, thus allowing a higher flexibility in the ambients adequacy. On the other hand, this project philosophy has lead to structural elements more and more slender and with natural frequencies much and much lower and, therefore, closer to the frequency of the dynamic excitation associated to the human beings activities, such as: walking, running, jumping, etc. Due to the reasons described in the previous paragraph, the structural engineering systems became sufficiently vulnerable to the effects of vibrations induced by small impacts as it is the case of walking of people on floors, resulting in discomfort to the people. It must be highlighted, also, that such project considerations have fulfilled the required limit states. However, the limit states of use for these structural systems need to be analysed, with no doubt, in a more sensible way. In this way, willing to contribute to supply subsidies to the structural engineers, in the dynamic analysis of structures subject to excitation induced by human beings, several loads models are developed to represent the act of walking. The space and time variation of the dynamic load is considered through the analysis and the transient effect of the impact of the human heel on the floor is taken into consideration, as well. In this way, It is considered in this dissertation, several structural models associated to composite floors (steel-concrete). In this study, it was considered the usual techniques of discretization, based on the Finite Element Method (FEM) using the computer program Ansys. An extensive analysis concerning the dynamic response of the floors is made, by means of the application of the developed load models, mainly, in terms of the values of the accelerations. The results obtained are compared to those supplied by the techinical literature available about the subject with the point of view associated to the human comfort. It is also investigated, the influence of the structural parameter variation on the dynamic response of the models, such as: span length, damping ratio, thickness of the slab and, also, rigidity of the beam columns. The results obtained along the study clearly indicate that the structural designers must be alerted to important distortions that may occur when the project rules are used without the necessary caution. Another important remark is regarded to the fact that in several analysed floors it is observed that the criteria of human comfort are not satisfied which demonstrate the importance of the consideration of the dynamic effect caused by human beings in the analysis of this type of problem. Atualmente, as novas tendências arquitetônicas e as exigências de mercado, vêm conduzindo a engenharia estrutural na busca por soluções cada vez mais arrojadas, as quais exigem grande experiência e conhecimento dos projetistas estruturais aliados a utilização de novos materiais e tecnologias. Esta filosofia de concepção estrutural está inserida em uma das mais importantes tendências de projeto dos últimos anos, ou seja: a busca por sistemas estruturais de rápida execução, dotados de peças de menor peso próprio e que possam vencer grandes vãos com um mínimo de elementos verticais, permitindo assim uma maior flexibilidade na adequação de ambientes. Por outro lado, esta filosofia de projeto tem conduzido a elementos estruturais cada vez mais esbeltos e com freqüências naturais cada vez mais baixas e, por conseguinte, mais próximas das faixas de freqüência das excitações dinâmicas associadas às atividades humanas, tais como: andar, correr, pular, etc. Devido as razões expostas no parágrafo anterior, os sistemas estruturais de engenharia tornaram-se bastante vulneráveis aos efeitos de vibrações induzidas por pequenos impactos como é o caso do caminhar de pessoas sobre pisos, resultando em desconforto para as pessoas. Deve-se destacar, ainda, que tais considerações de projeto têm atendido aos estados limites últimos. Todavia, os estados limites de utilização desses sistemas estruturais precisam ser analisados, sem sombra de dúvida, de maneira mais criteriosa. Deste modo, no sentido de contribuir para fornecer subsídios aos engenheiros estruturais, no que tange a análise dinâmica de estruturas submetidas a excitações induzidas pelos seres humanos, são desenvolvidos diversos modelos de carregamento representativos do caminhar das pessoas. A variação espacial e temporal da carga dinâmica é considerada ao longo da análise e, bem como, o efeito transiente do impacto do calcanhar humano nos pisos é levado em conta. Assim sendo, são considerados nesta dissertação diversos modelos estruturais associados a pisos mistos (aço-concreto). Técnicas usuais de discretização, com base no emprego do Método dos Elementos Finitos (MEF), via utilização do programa computacional Ansys, são consideradas neste estudo. Uma análise extensa acerca da resposta dinâmica dos pisos é feita, mediante o emprego dos modelos de carregamento desenvolvidos, principalmente, em termos dos valores das acelerações. Na seqüência, os resultados encontrados são comparados com aqueles fornecidos pela literatura técnica disponível sobre o assunto sob o ponto de vista associado ao conforto humano. Investiga-se, também, a influencia da variação de parâmetros estruturais sobre a resposta dinâmica dos modelos, tais como: comprimento vão, taxa de amortecimento, espessura das lajes e, ainda, rigidez das ligações viga coluna. Os resultados obtidos ao longo do estudo indicam, claramente, que os projetistas estruturais devem ser alertados para distorções importantes que ocorrem quando as normas de projeto são utilizadas sem o devido cuidado. Um outro importante diz respeito ao fato de que em diversos pisos analisados observa-se que os critérios de conforto humano não são satisfeitos, demonstrando a importância da consideração dos efeitos dinâmicos provenientes dos seres humanos na análise desse tipo de problema.