DSpace Collection: Thesis - Structural Engineering

SOFTWARE DEVELOPMENT FOR DESIGN OF SLAB AND T-GIRDER REINFORCED CONCRETE BRIDGES

Tue, 12 Feb 2013 05:43:35 GMT

Title: SOFTWARE DEVELOPMENT FOR DESIGN OF SLAB AND T-GIRDER REINFORCED CONCRETE BRIDGES

Authors: TEWODROS, TESFAYE

Abstract: In bridge design, engineers strive to plan an economical structure that will safely transmit loads to the ground without collapsing or deforming excessively. Since it is difficult to predict the exact loading and circumstances that a bridge must withstand, all bridge designs include a substantial margin of safety. Design standards vary throughout the world, but all aim at ensuring that new bridges will provide many years of service and will maintain an adequate margin of safety against failure. Bridge design involves a number of design steps which involves tidious calculations due to the presence of moving loads and needs choice of parameters and decision. So due to the complexity and time consumeness of the design we will be better off if we use bridge design programs to get better and accurate results in a short time. But the problem is these programs are too expensive to buy and use. Using pyrated softwares is illegal and immoral.And also using excel written programs has its own problems. This project appreciates the application of home made (self made) programs to make life easy and give a highlight on the procedure behind commercial softwares. This thesis is concerned with developing Software for design of slab and T-girder reinforced concrete bridges. The software is produced using Visual basic 6.0. The design is based on the standards on ERA 2002 Bridge design manual. The program analyzes and designs only Simple span slab and girder bridges and outputs in different forms are available. The user manual and the video tutorials will show how to use the software simply. Finally, conclusions and recommendations are made based on the produced software.

EFFECTS OF TORSION ON LATERAL STABILITY OF BUILDING STRUCTURES

Fri, 08 Feb 2013 12:20:08 GMT

Title: EFFECTS OF TORSION ON LATERAL STABILITY OF BUILDING STRUCTURES

Authors: Rahel, Tesfay

Abstract: This paper surveys the effects of torsion on the global lateral stability of a shear wall building with typical plan and elevation layouts. In order to achieve the goal of study, a parametric investigation procedure is undertaken, on a series of sample structures with a condition which can cause torsion and their lateral stability under earthquake and gravity loading is investigated and discussed. To study the effects of torsion on the lateral stability of building structures, three asymmetric models are constructed by moving the shear-wall couple in the centric model from grid lines “-X1_X1” to grid lines “X1_ X2” in one model, and to grid lines “X2_X3” and grid lines “X3_X4” in another models. In addition the effects of axial loading and increasing storey number on the lateral stability of building structures are parallely studied on one of the series models. To study the influence of storey number, three different stories are constructed on the same series model keeping their inter storey height constant. Load-displacement diagrams are constructed for the above three conditions and are shown in Figure 6-1_Figure 6-10. From the Load-displacement diagrams, global lateral stability “D” is computed. Reduction in global lateral stability due to the induced asymmetry proved to be (89%, 97% and 98%) respectively. Furthermore it is shown that the effect of axial loading is considerable in both the centric and eccentric wall configurations. And the lateral stability of a structure on the same configuration decreases while increasing storey number. Thus depending on the analysis results conclusions and recommendations are made and some further studies are forecasted.

Investigation of Alternative Design Forms of Precast Beam for Low Cost Buildings

Fri, 08 Feb 2013 12:02:51 GMT

Title: Investigation of Alternative Design Forms of Precast Beam for Low Cost Buildings

Authors: Melaku, Tesfaye

Abstract: It should not be puzzling to have 55% of the condominium house lottery winners did not show up interest to sign and receive ‘their’ houses, which is claimed to be low cost and affordable to lower and middle class society, this figure will be larger in country side towns. This still tells us the claiming low cost houses are still far beyond the affordable limit of the target group. In this study an endeavor is made to investigate structurally safe and economical forms of precast beam. Hence a new plane truss forms of precast beam is investigated and compared to the practicing space truss form of precast beam. The new model, though it has relatively shorter length of span for the similar sizes of bar, it is found reducing the cost by around 25% and mass (weight) of the beam by 33% for relatively similar span lengths.

EVALUATION OF THE EFFECT OF SHEAR WALL ARRANGEMENT IN DUAL SYSTEMS SUBJECTED TO LATERAL LOADS

Wed, 06 Feb 2013 09:32:41 GMT

Title: EVALUATION OF THE EFFECT OF SHEAR WALL ARRANGEMENT IN DUAL SYSTEMS SUBJECTED TO LATERAL LOADS

Authors: Abel, Yoseph

Abstract: Dual structural systems are still efficiently used by civil and structural engineers to address the public demand for residential buildings, schools, hospitals and office buildings. Furthermore, they are effective in resisting lateral loads by combining the advantages of their constituents. However, dual structural systems with moment frames are designed to carry lateral forces in longitudinal direction entirely while structural walls are positioned in shorter side of the building to resist transversal lateral loads are challenged by Northridge earthquake. After then, this type of dual system is cited by Erdy Charles k. (2007) as dangerous combination of shear walls and moment resisting frames. Hence, in an effort to address this problem, comparative analysis among the sample dual system buildings with different shear walls arrangement is carried out and overall seismic performance of the dual system is evaluated using non-linear push over analysis method. Three cases of shear wall arrangements for each sample building are used to examine the effect of different shear walls arrangement on the whole system, their interaction with frames and their out-of-plane bending resistance. Results of non-linear push over analysis are obtained for each case in the form of capacity curves and plastic hinge formation patterns. The observation of these results shows that the overall seismic resistance capacity is dependent on the shear wall location. Also it reveals that the shear walls are vulnerable to local failure due to bending moment in their out-of- plane direction, regardless of their location. Therefore, caution should have to be taken during designing of this type of dual system in order to avoid premature collapse of shear wall in its out-of-plane direction, which may perhaps leave the building defence less to transversal components of earth quake load.