Comparative study of structural response on multi-story buildings with shear wall and bracing systems

Multi-story buildings are designed to withstand lateral forces against earthquakes. There are several ways to strengthen multi-story building structures. One way is to add a dual system, namely the shear wall or the bracing systems. Shear walls and bracing techniques can resist earthquake forces in vertical and horizontal directions that occur in building structures. This study compares the results of the structural analysis to three structural models. The 10- story of the structural response used in the research includes the story drift, base shear, displacement, and structural behavior due to the earthquake force. Model 1 is a general structure without the shear wall and bracing systems, Model 2 is a structure completed with L-shear walls, and Model 3 is a structure installed with the X-bracing system. The analyses of three Models were carried out by SAP2000 software. The results show that the slightest interstory drift occurs in Model 2, namely 0.041 mm. The decrease in deviation value that arises in Model 2 is 12.6 mm, with 34.35%. In Model 1, the story drift exceeds the allowable limit, so that with such a model, it is not feasible. Therefore, it is necessary to add shear walls or a bracing system.

Stresses & Strains in Plate Girder with Different Bracing Systems under Combination of Loadings

Lateral buckling is one of the most important factors in the design of steel plate girder. This buckling in the girder can be controlled by many methods. The most popular method is to add the intermediate bracing systems along the length of girder. The unsafely designed intermediate bracing systems can easily lead to serious consequences in the construction stage due to lateral buckling by torsion which happens rapidly and suddenly when the internal force in girder exceeds the ultimate value. Reversely, if the intermediate bracing systems are designed excessively, their specific stiffness will be larger than the required one then it is very costly in both material and installing process In the present study different types of torsional bracing systems are used in twin plate girder of span 8m. As the behavior of plate girders with different type of bracing system changes differently along the length and depth. Changing the layout of bracing systems could also make the design easy and more economical. Keywords: Cross-frame Bracings, Horizontal Bracings, Plate Girder, Finite Element Analysis

Effect of the Bracing System on the Probability of Collapse of Steel Structures under Maximum Credible Earthquake

Simple bracing frames can be divided into two types in terms of concentric or eccentric. Concentric bracing frames are frames that intersect with other structural members at one point in the structure along the bracing members. Otherwise, the braced frame will be eccentric. It is said empirically that due to this type of shaping, eccentric bracing frames exhibit more ductile behavior and concentric bracing frames exhibit more stiff behavior. This behavioral difference caused this study to be numerically computing for five frames, including unique concentric and eccentric bracing frames of 5 and 10 stories and an ordinary 5-story concentric bracing frame. Their tensions and drift ratios should be acceptable for the use of residential buildings. Using the primary two steps of the new PEER probabilistic framework, namely, probabilistic seismic hazard analysis and structural analysis, which leads to the drawing of fragility curves, the probability of collapse is obtained to compare the safety capability of these frames according to their different characteristics against earthquakes. The results show that increasing the ductility or increasing the number of floors or the height of these systems can reduce collapse. Also, according to the results of the probability of collapse obtained in frames with 5-story concentric bracing frames, it can be said that some of the current regulations, which work based on previous approaches of analysis, can lead to unsafe structures with a high probability of collapse.

Literature Review on Interaction Analysis of Building Resting on Sloping Ground

An increase in economic growth, as well as urbanization in the hilly areas, encourages the construction in the hilly region. Considering this fact the engineers should assure the safety of constructions in the slopy region. To understand the past attempts carried out on the constructions of the building on the slopy ground the systematic literature survey is done which includes the parameters like types of the building suitable for hilly regions, slope inclinations for safe superstructure in seismic events, types of safety measures recommended to assure the safety of superstructure and necessity of interaction analysis for the constructions in the hilly region. The survey so carried out in the paper gives a fair idea about the research gap and thus motivates researchers to carry out future research on the gap identified. Keywords: soil-structure interaction; slopy ground; bracing system; literature survey; equivalent static analysis; hilly region constructions.

ANÁLISE DE SEGUNDA ORDEM DE ESTRUTURAS EM CONCRETO ARMADO

With the expressive increase in the demand for increasingly tall and robust constructions, plus more and more complex structural details that end up becoming a key element for the projects of the structures of the undertakings, it is important to consider the efforts made by the reinforced concrete structures are subjected. In this sense, the present work has as objective the approach of the parameters of global stability a and Yz followed by the verification of the efforts on the pavements and the displacements of the building caused by the loads acting on the structure. In this work, the use of the global stability parameter a and Yz, which is of fundamental relevance and also prescribed in NBR 6118 (ABNT, 2014), was evaluated. The use of the parameter a considered for the evaluation of the overall stability of the structure, but which is not capable of estimating second order efforts, allows us to classify a structure as being of fixed or mobile nodes. The Yz parameter, on the other hand, can be used to obtain second order efforts. To carry out this work, a case study was launched in the structural analysis software Ftool. The present analysis carried out showed that it is possible to conceive a bracing system for a building with up to 30 floors, using the pillar-wall solution having as a substitute resource for the aforementioned solution the solution of frames formed by beams and columns addressed continuously by tall building literature. Therefore, it is worth mentioning that the solution with wall pillars tends to be more expensive than the solution with frames, a system adopted in the development of this work due to the economic viability of the construction, in view of a higher consumption of materials in the superstructure and also higher costs in the construction. execution of foundations, due to the efforts that will be generated in the building (horizontal forces and bending moments).