Development of prefabricated modular houses in pure composite sandwich panels

Tese de Doutoramento (Programa Doutoral em Engenharia Civil)In the scope of the ClickHouse R&D Project, a residential modular temporary building was proposed and developed to accommodate, in urgent situations, dislocated families due to e.g. the occurrence of natural disasters. Proposed building is composed of a frame structure, panels and a tailored connection system. The frame structure and connection are composed of glass fibre reinforced polymer (GFRP) pultruded tubular profiles. While for the panels, composite sandwich panels made of polyurethane foam (PU) core and GFRP skins, are utilized. A new connection system is defined for connecting adjacent members. This modular construction of temporary housing, should be capable of being prefabricated according to the pultrusion technology (for the case of frame and connection components), transported at low cost to the area of installation (due to the reduced weight and being packed), and being easily and quickly assembled. In the ambit of the present thesis, the following research programs, which contributed for the ClickHouse outcomes, were developed: (I) material testing program; (II) development/ characterization of a connection system for jointing composite panels, (III) evaluation of the mechanical performance of single panel, two jointed panels and three jointed panels under flexural loading; (IV) assessment of single and two jointed wall panel’s behaviour under axial loading; (I) performance/characterization of two floor modular prototypes. Phase I is comprising comprehensive material testing program for establishing constitutive relation of the constituent materials of the sandwich panel, namely the PU foam core, GFRP skins and the bond between these two materials. Furthermore, bearing strength behaviour of GFRP skin and pultruded profiles is subjected to study in this phase. In the phase II, a connection system is proposed for connecting floor and wall sandwich panels. Proposed connection is composed of two main parts namely as end integrated Ushape GFRP profile and two connected tubular square GFRP profiles. The end former working as a connector by interlocking inside the U-shape profiles. Two approaches are used to study mechanical behaviour of jointed panels: friction technique and hybrid technique. An experimental program is performed to study the mechanical response of this connection system in the longitudinal and transversal directions. Phase III is included a series of experimental tests are carried out on a single panel, on two and three jointed panels. Flexural responses of the panels, in short term, is analysed, including evaluation of the failure mechanism and the efficiency of the proposed connection system between panels in jointing sandwich panels. Additionally, the creep behaviour of the panels, which is a limiting factor for their serviceability design, is investigated. Numerical and analytical models are proposed and verified including capturing the local failure of the panel using experimental program. The proposed models are used to go further in-depth to understand capability of connection in jointing panels and influence of U-shape GFRP profiles in increasing flexural stiffness of the panels. Additionally, contribution of single sandwich panels components in total shear deflection is investigated. In the phase IV, the structural performances of the sandwich wall panels under axial loading condition are experimentally tested and thereafter analytically assessed in two cases: (i) single wall panels; (ii) two jointed wall panels. The influence of the proposed connection system on the axial load capacity of the jointed panels is analytically evaluated. In phase V, performances of the two floor prototypes to support typical load conditions of residential houses are also assessed. The experimental program is complemented with an extensive finite element modelling and analytical study to verify the experiments results and to obtain connection flexibility, load distribution factor and stress distribution within the floor modular components. Additionally, several parametric studies are developed using FEM models developed and validated by varying geometric aspect ratios and numbers of U-shape GFRP profiles to show potentiality of this structure to have more housing space and consequently to extend this concept for other markets.No âmbito do Projeto I&D ClickHouse, uma habitação modular temporária foi proposta e desenvolvida para acomodar, em situações de urgência, famílias deslocadas, devido à ocorrência de e.g. desastres naturais. A habitação proposta é composta por uma estrutura porticada, painéis sanduíche e um sistema de conexão. A estrutura porticada e ligações são em perfis tubulares pultrudidos em polímeros reforçados com fibra de vidro (GFRP). Por sua vez, os painéis de sanduíche compósitos são constituídos por uma espuma de poliuretano (PU) no núcleo e lâminas de GFRP nas extremidades. Um novo sistema de conexão é proposto para a ligação de elementos adjacentes. Esta construção modular de alojamento temporário, pré-fabricada de acordo com a tecnologia de pultrusão (no caso da estrutura porticada e conexões), pode transportada a baixo custo para a área da instalação (devido ao peso reduzido e sistema embalamento), e ser fácil e rapidamente montada. No âmbito da presente tese, os seguintes programas de investigação, que contribuíram para os resultados do ClickHouse, foram desenvolvidos: (I) programa experimental de caracterização dos materiais; (II) o desenvolvimento/caracterização do sistema de conexão, (III) a avaliação do comportamento mecânico de um painel isolado, dois painéis e três painéis ligados entre si sob cargas de flexão; (IV) a avaliação do comportamento mecânico de um painel isolado e dois painéis ligados entre si sob carga axial; (I) performance/caracterização de dois protótipos de piso modular. A fase I é composta por amplo programa de ensaios dos materiais para o estabelecimento de relações constitutivas dos materiais constituintes do painel de sanduíche, ou seja, o núcleo de espuma PU, as lâminas de GFRP e a aderência entre estes dois materiais. Além disso, a resistência ao esmagamento das lâminas e perfis de GFRP para o caso de ligações mecânicas é também estudada nesta fase. Na fase II, um sistema de ligação é proposto para ligar painéis sanduíche de piso e de parede. O sistema de conexão proposto é composto de duas partes principais, nomeadamente (i) perfis GFRP em “U” integrados no contorno dos painéis e (ii) perfis retangulares em GFRP. A ligação entre painéis é por encaixe, sendo que os elementos (ii) realizam a respetiva ligação. Duas abordagens são usadas para estudar o comportamento mecânico dos painéis ligados: encaixe (apenas por atrito) e técnica híbrida (atrito e mecânica). Um programa experimental é realizado para estudar a resposta mecânica deste sistema de ligação nas direções longitudinais e transversais Na fase III inclui-se série de ensaios experimentais realizados num painel isolado, em dois e três painéis ligados entre si. A resposta à flexão dos painéis, a curto prazo, é analisada, incluindo a avaliação dos mecanismos de rotura e a eficiência do sistema de ligação. Além disso, o comportamento de fluência dos painéis, o que é um aspeto condicionante no dimensionamento deste tipo de painéis, é investigada. Modelos numéricos e analíticos são propostos e validados com recursos aos resultados experimentais obtidos. Os modelos propostos são posteriormente usados na compreensão da capacidade da ligação entre painéis no aumento da rigidez à flexão dos painéis. Além disso, a contribuição da deformação por corte na deformação dos painéis sanduíche é também investigada. Na fase IV, o desempenho estrutural dos painéis sanduíche de parede é testado experimentalmente, sob condições de carga axial, e posteriormente avaliados analiticamente, em dois casos: (i) painéis de parede isolados; (ii) dois painéis de parede ligados entre si. A influência do sistema de ligação proposto na capacidade de carga axial dos painéis é avaliada analiticamente. Na fase V, o desempenho de dois protótipos modulares é avaliada para as condições de carga típicas de habitações residenciais. O programa experimental é complementado com uma extensa simulação numérica e analítica para verificar os resultados experimentais e obter a flexibilidade de ligação, o fator de distribuição de carga e a distribuição de tensões nos componentes modulares do piso. Além disso, vários estudos paramétricos foram desenvolvidos utilizando modelos FEM para mostrar a potencialidade do sistema ser aplicável a estruturas de vãos superiores e, consequentemente, estender este conceito para outros mercados

Design of an innovative self-compacting material modified with recycled steel fibers and spent equilibrium catalyst for ultra-high performance applications

The main aim of the present study is to design an innovative self-compacting material modified with recycled steel fibers (RSF) from waste tires and spent equilibrium catalyst (Ecat) from the petrochemical industry for ultra-high performance application. For this purpose, 17 different mixtures were developed and analysed using different percentages of RSF (0%-3%) and replacement of cement by different percentages of Ecat (0%-15%). The developed mortars' self-compatibility was evaluated in a fresh stage using mini-cone tests. Regarding the hardened stage, the mortars were characterized at the ages of 7 days and 28 days using compression and unnotched flexural tests. The abilities of RSF to increase the post-cracking behavior of the specimens and to use Ecat to increase the bond performance between RSF and the cement matrix were assessed by performing notched three-point bending tests. The results of notched flexural tests were used to obtain the residual flexural strength in service limit state (SLS), ultimate limit state (ULS), and two equivalent flexural strengths. The experimental results for the fresh stage demonstrated that inclusion of RSF and Ecat significantly reduced the workability of mortars. The beneficial use of RSF and Ecat was observed to increase compressive strength and flexural strength for 7 days and 28 days of tested specimens. Notched flexural tested specimens showed that the addition of RSF and Ecat can significantly decrease the brittle behavior of cement-based materials by improving its toughness and post-cracking resistance. Middle-span deflection, crack initiation load, and ultimate flexural load were also increased with the addition of RSF and Ecat. In this sense, the results of this research showed that RSF and Ecat seem to have the potential to constitute a sustainable material for structural and nonstructural applications

FEM-based numerical strategy for analysis of composite modular floor prototype for emergency housing applications

The paper presents the numerical modelling of a temporary residential floor prototype composed of three jointed composite floor sandwich panels made of glass fiber reinforced polymer (GFRP) skins, a polyurethane foam core (PU) and pultruded U-shaped GFRP profiles working as ribs. Panels are supported on a GFRP pultruded frame structure. A 3D nonlinear finite element model is developed considering geometrical and material nonlinearities and adherent surfaces interaction. The model is coherently validated with experimental results, showing its capability to capture the mechanical performance of a single panel (which includes the possibility of local instability on the GFRP skin), two and three panels working together, and the whole prototype. A series of parametric studies are then conducted using the numerical model developed. Those studies aim to (i) assess the influence that ribs on the panel stiffness and on the shear stresses distribution through the sandwich panel’s components, (ii) the flexibility of the designed connections between jointed panels and frame structure, and (iii) the influence of geometry in the modular housing.This work is part of the research project ClickHouse – Development of a prefabricated emergency house prototype made of composites materials, involving the company ALTO – Perfis Pultrudidos, Lda., CERis/Instituto Superior Técnico and ISISE/University of Minho, supported by FEDER funds through the Operational Program for Competitiveness Factors – COMPETE and the Portuguese National Agency of Innovation (ADI) – project no. 38967. Special thanks are given to company ALTO – Perfis Pultrudidos, Lda., who manufactured all the elements (GFRP profiles and sandwich panels) involved in the research. The numerical model was performed in collaboration with the Department of Construction Engineering of the Universitat Politècnica de València

Axial performance of jointed sandwich wall panels

Throughout this paper, a new system for connecting composite sandwich wall panels is proposed. The relevant structural components are investigated with the aim of utilizing these panels as insulated wall elements in building applications or prefabricated modular systems. The adopted sandwich wall panels are composed of hand-layup Glass Fiber Reinforced Polymer (GFRP) outer skins and low density closed polyurethane (PU) foam core. The sandwich wall panels present an overall geometry of 2880×960×64 mm3. One challenge of the proposed new system that was examined included joining the panels in the longitudinal direction (along their height) and transversally connecting (along their width) to other structural elements, similar to beams at the bottom and top. The structural performance of the sandwich wall panels was experimentally tested and thereafter analytically assessed in two cases: (i) single wall panels; (ii) two jointed wall panels. Outward localized GFRP wrinkling, followed by global buckling was observed as the dominant failure mode in both cases. Further, the capability of the proposed connection system to increase the axial load capacity of the jointed panels was evaluated. The study illustrates that axial capacity of two jointed sandwich wall panels compared to the single sandwich wall panel, increased substantially from 91% to 152% depending on the failure modes.This work is part of the research project ClickHouse - Development of a prefabricated 595 emergency house prototype made of composites materials, involving the company ALTO – 596 Perfis Pultrudidos, Lda., CERis/Instituto Superior Técnico and ISISE/University of Minho, supported by FEDER funds through the Operational Program for Competitiveness Factors – 598 COMPETE and the Portuguese National Agency of Innovation (ADI) - project no. 38967. 599 Special thanks are given to company ALTO who manufactured all the elements (GFRP 600 profiles and sandwich panels) involved in this work. ClickHouse - FEDER / COMPETE / ADI - project no. 38967.info:eu-repo/semantics/publishedVersio

Caracterização experimental do comportamento mecânico de painéis sandwich com lâminas de GFRP e núcleo de poliuretano

Neste trabalho apresentam-se os resultados de um programa experimental realizado no piso da laje de um protótipo destinado a habitações de emergência em materiais compósitos. Este piso é constituído por painéis sandwich, com lâminas de GFRP e núcleo de poliuretano, apoiados em vigas e pilares em perfis pultrudidos em GFRP. O trabalho realizado tem como objetivo fundamental o estudo do comportamento estrutural do piso, incluindo a determinação de parâmetros modais dos painéis sanduíche analisados

Development of a composite prototype with GFRP profiles and sandwich panels used as a floor module of an emergency house

A series of experimental tests carried out on a composite prototype to be used as a floor module of an emergency house is presented in this paper. The prototype comprises a frame structure formed by GFRP pultruded profiles, and two sandwich panels constituted by GFRP skins and a polyurethane foam core that configures the floor slab. The present work is part of the project “ClickHouse – Development of a prefabricated emergency house prototype made of composites materials” and investigates the feasibility of the assemblage process of the prototype and performance to support load conditions typical of residential houses. Furthermore, sandwich panels are also independently tested, analysing their flexural response, failure mechanisms and creep behaviour. Obtained results confirm the good performance of the prototype to be used as floor module of an emergency housing, with a good mechanical behaviour and the capacity of being transported to the disaster areas in the form of various low weight segments, and rapidly installed. Additionally, finite element simulations were carried out to assess the stress distributions in the prototype components and to evaluate the global behaviour and load transfer mechanism of the connections.Quadro de Referência Estratégica Nacional (QREN)FEDER funds through the Operational Program for Competitiveness Factors – COMPETE and the Portuguese National Agency of Innovation (ADI) - project no. 3896

Composite modular floor prototype for emergency housing applications: Experimental and analytical approach

Manuscript versionThe present paper explores a new modular floor prototype to be used in emergency houses. The prototype is composed of a frame structure made of glass-fibre-reinforced polymer tubular pultruded profiles, a slab made of sandwich panels with a polyurethane foam core and glass-fibre-reinforced polymer skins, and a tailored connection system that provides integrity between assembled components. A series of experimental tests are carried out including flexural tests on a single panel, on two and three connected panels, and on the assembled floor prototype. The behaviour of the panels is analysed when they are not considered part of the glass-fibre-reinforced polymer framed structure, namely the failure mechanisms and the efficiency of the proposed connection system between the panels. The performance of the floor prototype to support typical load conditions of residential houses is also assessed. Additionally, an analytical model was used to deeper study the behaviour of the developed sandwich panels, connection system and the modular floor prototype.SFRH/BSAB/114302/2016; ADI - project no. 38967info:eu-repo/semantics/publishedVersio