Although rice straw and other grains have been used in building since pre-history, in the past two decades, there has been a move to utilize this rapidly renewable, locally available, agricultural byproduct as part of the sustainable construction movement. Up to this point, this has been done by simply stacking up the full straw bales. Stak Block, invented by Oryzatech, Inc., is a modular, interlocking block made of a composite of rice straw and binding agent that serves as an evolution in straw construction. This study investigates the feasibility of using these Stak Blocks as a structural system. The report was divided into four main parts: material testing, development of effective construction detailing, full-scale physical shear wall testing, and a comparison with wood framed shear walls. The first section investigated the feasibility of using the Stak Blocks in a load-bearing wall application. Constitutive properties of the composite straw material such as yield strength and elastic stiffness were determined and then compared to conventional straw bale. Next, the decision was made to prestress the walls to create a more effective structural system. Various construction detailing iterations were evaluated upon the full-scale shear wall testing using a pseudo-static cyclic loading protocol. Finally, the available ductility of the prestressed Stak Block walls in a lateral force resisting application is quantified along with an approximation of potential design shear forces. It was determined that the Stak Block material performed satisfactorily in gravity and lateral force resisting applications, in some respects better than conventional wood-framed construction, and has great potential as a seismically-resistant building material.

The purpose of this master thesis has been to investigate the possibility to increase the damping capacity of shear walls with the use of glue in combination with nails. It has been done with experiment and with FE-simulations.   The first experimental part is tensile tests of four different glue types which have been analyzed to get material data. The second experimental part is analysis of glued-nail joint in shear test. FE-simulations of glued-nail joints are finally done in Abaqus/CAE.   The experiments in shear tests of glued-nail joints showed that two glues failed and could not be used for further analysis. The two other glues had an increase in damping capacity compared with results from nail joint.   Further FE-simulations of glued-nailed joints have to be done in order to calibrate the FE-model with the results of glued-nailed joints in shear tests. The uncertainty is found in the material properties of the glue, experimental test data was not adequate. The conclusion is that glued-nail joints can increase the damping capacity in shear walls. / Damping capacity, shear wall, hysteresis, shear test, finite element method, Abaqus/CAE

This thesis presents three methods to estimate and locate damage in framed buildings, simply-supported beams and cantilever structures, based on experimental measurements of their fundamental vibration modes. Numerical simulations and experimental essays were performed to study the effectiveness of each method. A numerical simulation of a multi-storey framed building, a real bridge and a real chimney were carried out to study the effectiveness of the methodologies in identifying damage. The influence of measurement errors and noise in the modal data was studied in all cases. To validate the experimental effectiveness of the damage estimation methods, static and dynamics tests were performed on a framed model, a simply supported beam, and a cantilever beam in order to determine the linear behavior changes due to the increase of the level of damage. The structural identification algorithms during this thesis were based on the knowledge type of the stiffness matrix or flexibility matrix to reduce the number of modal shapes and required coordinates for the structural assessment. The methods are intended to develop tools to produce a fast response and support for future decision procedures regarding to structures widely used, by excluding experimental information, thereby allowing a cost reduction of extensive and specific testing

No description available.

The amount of total and relative sway of a framed or a composite (frame-shear wall) building is of utmost importance in assessing the seismic resistance of the building. Therefore, the design engineer must calculate the sway profile of the building several times during the design process. However, it is not a simple task to calculate the sway of a three-dimensional structure. Of course, computer programs can do the job, but developing the three-dimensional model becomes necessary, which is obviously tedious and time consuming. An easy to apply analytical method is developed, which enables the determination of sway profiles of framed and composite buildings subject to seismic loading. Various framed and composite three-dimensional buildings subject to lateral seismic loads are solved by SAP2000 and the proposed analytical method. The sway profiles are compared and found to be in very good agreement. In most cases, the amount of error involved is less than 5 %. The analytical method is applied to determine sway magnitudes at any desired elevation of the building, the relative sway between two consecutive floors, the slope at any desired point along the height and the curvature distribution of the building from foundation to roof level. After sway and sway-related properties are known, the requirements of the Turkish Earthquake Code can be evaluated and / or checked. By using the analytical method, the amount of shear walls necessary to satisfy Turkish Earthquake Code requirements are determined. Thus, a vital design question has been answered, which up till present time, could only be met by rough empirical guidelines. A mathematical derivation is presented to satisfy the strength requirement of a three-dimensional composite building subject to seismic loading. Thus, the occurrence of shear failure before moment failure in the building is securely avoided. A design procedure is developed to satisfy the stiffness requirement of composite buildings subject to lateral seismic loading. Some useful tools, such as executable user-friendly programs written by using &ldquo / Borland Delphi&rdquo / , have been developed to make the analysis and design easy for the engineer. A method is also developed to satisfy the ductility requirement of composite buildings subject to lateral seismic loading based on a plastic analysis. The commonly accepted sway ductility of &amp / #956 / &amp / #916 / =5 has been used and successful seismic energy dissipation is thus obtained.

Over the last decade, six major earthquakes that occurred in Turkey dramatically demonstrated the poor performance of the buildings that were designed and constructed far from Turkish seismic code&rsquo / s requirements. The Marmara region, where most of the population and industry is located, is in the active seismic zone. With the rising cost of damages due to earthquakes, the necessity of the cost-benefit analysis for various rehabilitation strategies used in existing buildings has become a major concern for the decision makers who are in the position of making decisions on the building rehabilitation This study evaluates the performance of two different rehabilitation strategies applied to two five-story reinforced concrete buildings and assesses their cost-benefit analyses. These buildings were chosen to be representative of the typical residential To carry out the structural analysis of the buildings, three-dimensional models of the buildings were developed using SAP2000 [6]. Two alternative strengthening methods, insertion of reinforced concrete shear walls and application of Carbon Fiber Reinforced Polymers (CFRP) on hallow clay tile infill walls, were used for both of the buildings. While modeling infill walls strengthened with CFRP, two specific modeling attempts proposed by the researchers at Middle East Technical University were used. Pushover analyses were performed to evaluate seismic performance of the buildings. The Life Safety criterion was chosen as the rehabilitation objective. The global and component response acceptability limits were checked and the cost-benefit analysis was performed in order to determine the most attractive rehabilitation alternative. The results and comparisons given here illustrated that strengthening with shear wall had the most significant improvement on the seismic performance and cost effectiveness of the case study buildings. Outcomes of this study are only applicable to the buildings employed here and are bound by the assumptions made, approximations used and parameters considered in this study. The findings cannot be generalized for the buildings rehabilitated with CFRP due to lack of the consistent models for CFRP application. More research needs to be conducted to provide solid guidelines and reliable models applicable to the CFRP rehabilitated infill walls.

La plupart des bâtiments de moyenne et grande hauteur en béton armé sont munis de murs de refend ductiles afin résister aux charges latérales dues au vent et aux séismes. Les murs de refend ductiles sont conçus selon des règles conception stricts. Ces murs sont généralement conçus de façon à forcer la formation d’une rotule plastique à leur base dans l’éventualité d’un séismemajeur. Lors de la conception d’un mur, l’enveloppe des moments fléchissants ainsi que l’enveloppe des efforts tranchants dans la portion du mur situé au-dessus de la rotule plastique sont basés sur la résistance probable en flexion du mur dans la région de la rotule plastique. Plusieurs études sur les murs de refend conçus selon cette philosophie de conception on fait le constat que l’effort tranchant maximum dans un mur peut être sous-estimé lors d’un séisme, et que des rotules plastiques peuvent également se former à d’autres endroits qu’à la base du mur, ce qui constitue un mécanisme de ruine indésirable. Ces effets sont principalement attribuables à la contribution des modes supérieures à la réponse dynamique globale des bâtiments lors d’un séisme. L’effet des modes supérieurs est particulièrement important dans les bâtiments élancés de grande hauteur ayant une période propre de vibration longue. L’essai pseudo-dynamique avec sous-structure est uneméthode efficace et économique d’évaluer expérimentalement l’effet des modes supérieurs sur le comportement sismique des murs de refend dans les bâtiments. Lors de tels essais, comme la masse du bâtiment est modélisée numériquement, ceci permet de tester des structures à de relativement grandes échelles sans avoir à combattremécaniquement les forces d’inerties générées lors d’un séisme. Dans le cadre de la présente étude, la portion constituant la base d’un mur de refend correspondant à la zone de rotule plastique faisant partie d’un bâtiment de huit étages à l’échelle 1/2,75 a été testé. Les dimensions générales de la portion de mur testée étaient de 1800 mm de longueur, par 2200 mm de hauteur par 160 mm d’épaisseur. Le mur étudié a été conçu selon l’édition 2015 du Code National du Bâtiment du Canada (CNBC 2015) ainsi que selon la norme CSA A23.3-14 (Calcul des ouvrages en béton), où le facteur d’amplification de l’effort tranchant causé par l’effet des modes supérieurs n’a pas été pris en compte. Lors des essais pseudo-dynamiques avec sous-structure, une nouvelle méthode de contrôle à trois degrés de liberté convenant à des spécimens d’essai très rigides axialement a été développée et validée. Une procédure novatrice de redémarrage d’un essai interrompu en cours de route a également été développée et validée. Lors des essais, le bâtiment de huit étages incluant la portion de mur dans le laboratoire a été soumis à trois séismes. Le premier séisme était de très faible intensité, l’intensité du deuxième séisme correspondait au séisme de conception, et le troisième séisme correspondait au séisme de conception dont l’intensité a été doublé. Durant les deux séismes de forte intensité, le mur testé s’est comporté de manière ductile et des fissures de cisaillement et de flexion importantes ont été observées. Même si l’effort tranchant maximum mesuré durant le séisme de conception a atteint 2,16 fois la valeur de conception du mur, et 3,01 fois la valeur de conception du mur dans le cas du séisme amplifié, aucun mécanisme de ruine n’a été observé. Suite aux essais pseudo-dynamiques avec sous-structure, un essai par poussée progressive a également été effectué. Les résultats des essais pseudo-dynamiques avec sous-structure portent à croire que la valeur de l’effort tranchant de conception d’un mur selon la norme CSA A23.3-14 est sous-estimé. De plus, l’essai poussée progressive a permis de démontrer que lemur était beaucoup plus résistant qu’anticipé, puisque l’effort tranchant avait été sous-estimé lors de la conception. L’essai par poussée progressive a également permis de démontrer que le mur peut atteindre des niveaux de ductilité en déplacement supérieur à celui prévu par la norme CSA A23.3-14. / Abstract: Most mid- and high-rise reinforced concrete (RC) buildings rely on RC structural walls as their seismic force resisting system. Ductile RC structural walls (commonly called shear walls) designed according to modern building codes are typically detailed to undergo plastic hinging at their base. Both the design moment envelope for the remaining portion of the wall and the design shear forces are evaluated based on the probable flexural resistance of the wall in the plastic hinge region. Several analytical studies have shown that so-designed structural walls can be subjected to shear forces in excess of the design values. Plastic hinging can also develop in the upper portion of the walls. These effects are mainly attributed to higher mode response and, hence, are more severe in taller or slender walls with long fundamental periods. Considering the literature, there is a significant uncertainty regarding the behavior of the structural walls under the higher mode of vibrations excited under earthquake excitations. Hybrid testing is an effective experimentalmethod to study the natural behaviour of structures such as shear walls. The hybrid testing method enables the simulation of the seismic response of large structural elements like RC shear walls without the need to include large masses typically encountered in multi-storey buildings. In this study a barbell shaped RC shear wall specimen of 1800mm in length including a 300mm × 300mm boundary element at each end that is 2200mm in height, and 160mm thick was investigated. A test specimen corresponding to the base plastic hinge zone of an 8-storey shear wall was tested in a laboratory evolvement whilst the reminder of the building structure was modeled numerically. The reference wall was scaled down by a factor of 1/2.75 to obtain dimensions of the test specimen. The RC wall was designed in accordance with the 2015 edition of the National Building Code of Canada (NBCC 2015) and the Canadian Standard Association A23.3-14 code. The amplification of the base design shear force accounting for the inelastic effects of higher modes specified by the CSAA23.3-14 standard was not taken into account in order to evaluate the amplification experimentally. In order to investigate the response of ductile RC walls under earthquake ground motions and track the effect of the higher vibration modes on the shear force demand, three earthquakes with different intensities were applied on the hybrid model successively. The RC wall exhibited a ductile behaviour under the ground motions and flexural and shear cracks developed all over the height of the wall. In spite of amplifying the shear force demand by a factor of 2.16 under the design level earthquake and 3.01 under a high intensity earthquake, no shear failure was observed. The test results indicated that the amplification of the design shear forces at the base of ductile RC shear walls are underestimated by the CSAA23.3-14 standard. A new method for controlling three degrees of freedomin hybrid simulation of the earthquake response of stiff specimens was developed and verified in this study. Also, an innovative procedure to restore an interrupted hybrid test was programmed and verified. The hybrid tests were followed by a push-over test under a lateral force distribution equal to the square root of sum of the squares of the first five modes in order to evaluate the displacement ductility of the RC wall. Findings of the final push-over test showed that the tested ductile RC wall can withstand higher displacement ductilities than the presented levels in the NBCC 2015.

Cette thèse s'inscrit dans le cadre de l'élaboration de méthodes simplifiées d'analyse du comportement non-linéaire des ouvrages en béton armé à voiles porteurs sous action sismique. Une stratégie de modélisation simplifiée basée sur la notion de macro-éléments a été adoptée, afin de décrire le comportement non-linéaire du mur voile et d'estimer sa capacité résistante vis-à-vis des forces latérales. Les lois de comportement utilisées pour le béton et l'acier sont basées sur la théorie de l'endommagement et de la plasticité. La validation des capacités prédictives du modèle à partir des résultats expérimentaux a été aussi effectuée. De plus, une étude paramétrique a été réalisée pour étudier la sensibilité des résultats aux variations des paramètres liés au modèle, au matériau et/ou type de chargement. / Abstract

The research was focused on the three major structural elements of a typical cold-formed steel building - shear wall, floor joist, and column. Part 1 of the thesis explored wider options in the steel sheet sheathing for shear walls. An experimental research was conducted on 0.030 in and 0.033 in. (2:1 and 4:1 aspect ratios) and 0.027 in. (2:1 aspect ratio) steel sheet shear walls and the results provided nominal shear strengths for the American Iron and Steel Institute Lateral Design Standard. Part 2 of this thesis optimized the web hole profile for a new generation C-joist, and the web crippling strength was analyzed by finite element analysis. The results indicated an average 43% increase of web crippling strength for the new C-joist compared to the normal C-joist without web hole. To improve the structural efficiency of a cold-formed steel column, a new generation sigma (NGS) shaped column section was developed in Part 3 of this thesis. The geometry of NGS was optimized by the elastic and inelastic analysis using finite strip and finite element analysis. The results showed an average increment in axial compression strength for a single NGS section over a C-section was 117% for a 2 ft. long section and 135% for an 8 ft. long section; and for a double NGS section over a C-section was 75% for a 2 ft. long section and 103% for an 8 ft. long section.

No description available.