The Seismic Behavior Of Multistory Frame Structures

This document’s purpose is to look for various available bracings used in a steel structure, which can be applied during construction to prevent the building from succumbing to the damage occurred due to the lateral movement, vertical movement, oscillatory movement, etc. caused by the seismic forces such as earthquake force and also forces such as wind load acting laterally.

The improvement of the skyscraper structures starts from 10 floor stories to high as 150 floor stories high. The Reliance Building Chicago, USA, in 1895, 15 stories high used the semi-rigid steel frame. The semi-rigid steel frame was held together with steel beams and connected by rivets. (Bennett, P.42) The 60 stories high First Wisconsin Center, Milwaukee, USA in 1974 employed the steel belt truss with framed shear truss. This structure used the horizontal trusses at the upper and lower stories to enhance the framed shear truss. (Bennett, P.44) The Sears Tower, Chicago, USA, in 1974, 110 stories high used the Bundled tube. The bundled tubes were made up of a cluster of connected frame tubes, reinforced by steel beams at each story to increase the strength of the structure. Various tubes terminated at different level to further strengthen the bundled tubes at the center. (Bennett, P.44) The future structure was the Superframe, which can reaches at least 150 stories high. It used the concept of the Eiffel Tower with framed tubes connected by horizontal trusses. (Bennett, P.45) It was the innovation of the structural design that enables skyscrapers to reach new height. These methods include the use of

Today, some building codes may require a more rigorous structural design methodology than is associated with conventional construction. This requirement may result from a need for better building performance when the structure is exposed to moderate-to-high wind, seismic, and snow loads. An example of published

In the quake zone the Forbidden city in Beijing has stood for centuries past and in the documentary, Secrets of Chinas Forbidden City, the secret to the structural survival where unveiled. To determine the quake level that the Forbidden city building structure can withstand, a 1/5 scale model was constructed from the timber frame that is used in the palace of longevity and health. The construction method that was used is that of the traditional carpentry tools and techniques. Due to the simple joint connection that allow mobility during the earthquakes the forbidden city has lasted for centuries. The columns that holds the weight of the building are not connected to the stone bases, which allow the building to move freely and enabling the flexibility

1. When building a structure to withstand an earthquake, there are many ideas and strategies necessary to consider in order to create a successful building. In order to conserve resources and manage the limited building time effectively, I had to consider the most important areas to reinforce my tower. For example, my group spent much of our time building reinforcements between joints and areas that would be under strain during testing (such as the bases of each of our tower’s floors). This focus on areas that would be more vital to the survival of our tower during testing proved to be extremely important to my group because we were able to make much-needed last-minute adjustments and improvements to our tower with the excess time that our efficient reinforcement design created. Another consideration that my group had to make when designing our tower was how to build the structure sturdily enough to hold the required weight that our tower must carry during the tests. To do this, my group planned two rigid floors that were reinforced with multiple sturdy supports comprised of straws and popsicle sticks. In addition, my group also secured our floors be securely attaching each one to our tower’s frame with rubber bands, tape, and string. Despite the challenges that these considerations presented during the building and design process of the Earthquake structure project, carefully contemplating and observing each one proved to be a decisive factor in the

Earthquake engineering is a subject where a person can be overwhelmed with information but still crave for knowledge due to its unpredictable nature. Earthquakes are a natural repetitive occurrence on planet earth, which due to its devastating impact, have caused a lot of damage to structures and caused loss of life. Therefore engineers, scientists and geologists were required to take action and one of the many first steps was to identify the regions of seismic activity. The argument in this essay is not how to prevent earthquakes as that is out of the control of humans but how to minimise the damage and deaths caused by them by designing better buildings. The challenge to first achieve this goal was by engineers in America, where in 1906, in the state of California, due to the frequent earthquakes in the state, building design codes and safety standards were established. These design or seismic codes have helped to reduce the damages caused by earthquakes. Therefore the solution for people in active seismic zones is to adhere to the seismic codes strictly, designed by engineers in order to help strengthen buildings and reduce the loss of life when an earthquake occurs.

Elastic high-strength steel cables run down the center of the system’s frame. The cables control the rocking of the building and, when the earthquake is over, pull it back into proper alignment.

3 powerhouse-dam section, utilizing an elasto-plastic FEM approach. The practices of rock and concrete were simulated by utilization of direct strong isoparametric elements, and the behaviour of rock bridges, joints and foundation surfaces were modeled utilizing quadratic joint elements. The mechanical parameters of the stone, joints, foundation surfaces, and additionally concrete utilized as a part of this numerical modeling, are the same as those embraced in the physical modeling. Considering the Drucker–Prager failure criterion yields a smooth failure surface and is quite convenient for finite element analyses, it was adopted as the plastic potential for the intact rock blocks and concrete structure The Mohr– Coulomb criterion was considered as the failure paradigm of joint elements. The shear stiffness and normal stiffness of joints are dictated by the slopes of the stress– strain curve in research center tests [19– 20]. The shear stiffness ks and normal stiffness kn of rock bridges are figured utilizing the mechanical properties of intact rocks The computational model of the dam foundation has a size of 160m in depth, 95m in length directing upstream from the dam heel and 220m in length directing downstream from the dam toe. For the boundary conditions, the normal displacement limitations were applied to the upstream and downstream boundaries of the numerical model, while a fixed displacement constraint is applied to the bottom boundary.

Structural researchers have realized the beam-column joint’s effects and consequences on the stability and durability of structures since the last century. Many buildings were collapsed under exposure to earthquakes; in most cases the main reason for its collapse is the local failure in beam-column joints. Therefore, many attempts have been done by structural researchers all over the world to overcome these crises by improving the resistance capacity of joints. The amount of steel reinforcement both longitudinal or transverse direction, and distribution pattern of it have a significant effect on the behavior of joints.

This work aims to study the seismic performance with different soil condition like hard, medium and soft of multi-storied buildings having plan regularities. The buildings were analyzed by software STAAD Pro. The result obtained in term of percentage change in base shear and peak story shear.

In some cases, lateral force shapes result to good approximation of demand displacements. Nevertheless, there has not been found any constant loading for exact approximation of local mechanisms and plastic hinges. Earthquake codes have made it mandatory to use a minimum of two lateral load patterns in nonlinear static procedure. These two load patterns are chosen to cover resulting forces in actual dynamic response of the structure. There are two load patterns which are used mostly in usual studies: uniform and modal load pattern. When using uniform load pattern, called also constant acceleration pattern, lateral forces applied to the structure are proportional to the mass of the building stories. This load pattern emphasizes on bottom floors demands more than top floor demands. It also increases the importance of shear in stories against overturning moment while modal load pattern emphasizes overturning moment and story demands. The FEMA356 code allows using comparative load pattern instead of constant load pattern. In this method the load pattern varies by plastic hinges as the displacements in the structure increase.

Shear walls are structural members used to elongate the strength of R.C.C. structures. These shear walls will be construct in each level of the structure, to form an effective box structure. Equal length shear walls are placed symmetrically on opposite sides of outer walls of the building. Shear walls are added to the building interior to provide more strength and stiffness to the building when the exterior walls cannot provide sufficient strength and stiffness. It is necessary to provide these shear walls when the tolerable span-width ratio for the floor or roof diaphragm is exceeded. The present work deals with a study on the improvement location of shear walls in symmetrical high rise building. Position of shear walls in symmetrical buildings has due considerations. In symmetrical buildings, the center of gravity and center of rigidity coincide, so that the shear walls are placed symmetrically over the outer edges or inner edges (like box shape). So, it is very necessary to find the efficient and ideal location of shear walls in

Abstract: This study aimed to compare the seismic behaviour of different bracing systems in 10th time smaller real prototype steel building model. The uniaxial shake table experiment was carried out to assess the structural performance on different bracing systems in same storey height building (model type-I) and different storey height building (model type- II). Three structural configurations were used: bare frames (BFs), X- braced frames (XBFs) and Diagonal braced frames (DBFs). The effects of some parameters influencing the seismic performance, including the type of the bracing system, the storey height of the were investigated. The results show that the different braced frames performed well in terms of joint displacement and performance point when compared to the simple bare frame frame in steel buildings. It can be concluded with a comparative account of the obtained results, that use of XBF and DBF enhances structural performances. DBF shows highly effective and economical because of it consume lesser material and give effective result.

Over the past quarter century, many of both the experimental and analytical studies have increased dramatically on the monotonic behavior of FRP-confined concrete columns, and as a result, many axial stress-strain models have been proposed; however, most of them have focused largely on FRP-confined plain concrete cylinders numerous people tested (e.g., Mirmiran and Shahawy 1997; Mirmiran et al.1998; Xiao and Wu 2000; Lam and Teng 2002, 2003; Berthet et al.2005; Almusallam 2007; Benzaid et al.2008; Eid and Paultre 2007, 2008; Teng et al.2009; Smith et al. 2010; Cui et al.2010). A certain number of these researches have included non-circular unreinforced (plain) columns (e.g., Rochette and Labossiere 2000; Ilki and Kumbasar 2002; Youssef 2003; Rousakis et al.2007; Youssef et al. 2007; Benzaid et al.2008; Wu and Wei 2010; Wu and Zhou 2010; Benzaid and Mesbah 2013). Owing to the limited progress of the experimental investigations carried out on FRP-confined non-circular reinforced concrete columns (RC) tested under cyclic axial compression loading, a well-defined study indicates that a few essential gaps need more further research. As a result, the current study aims to consider the most significant issues, namely, the influence of 1) cross-sectional aspect ratio, 2) internal hoop or longitudinal steel reinforcement ratio, and 3) cyclic or monotonic compression loading pattern. These issues which form the basis of the experimental program on CFRP-confined rectangular reinforced

Two papers to study the behavior of partially prestressed continuous composite beams consisting of a concrete slab supported by a steel beam were presented by Basu et al. (1987) [7, 8]. In these researches, the prestress was introduced in the negative moment regions only . The first paper presented analytical study on the effect of prestressed on crack prevention in the negative moment region and savings in material due to superior structural action. It was concluded that partial prestressing increased the load capacity of the beam by about 20% and eliminated the problem of concrete deck cracking in the negative moment region. It was also concluded that the deflection of the prestressed beam is about thirty percent less than that of the non-prestressed beam. The results of tests on a model of continuous