The Structural Design of Tall and Special Buildings

Bayraktar, Alemdar; Sevim, Bariş; Altunişik, Ahmet Can; Türker, Temel

doi: 10.1002/tal.464pmid: N/A

This paper describes a Turkish style reinforced concrete minaret, its finite element model, modal testing, finite element model updating and earthquake behaviour, before and after model updating. The minaret of a mosque located in Trabzon, Turkey is selected as an application. A three‐dimensional (3D) model of the minaret and its modal analysis is performed to obtain analytical frequencies and mode shapes using ANSYS finite element program. The ambient vibration tests are conducted on the minaret under natural excitations such as wind effects and human movement. The output‐only modal parameter identification is carried out by Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification methods in Operational Modal Analysis software and in doing so, dynamic characteristics (natural frequencies, mode shapes and damping ratios) are determined. A 3D finite element model of the minaret is updated to minimize the differences between analytical and experimental modal properties by changing some uncertain modelling parameters such as material properties and boundary conditions. The earthquake behaviour of the minaret is investigated using 1992 Erzincan earthquake before and after finite element model updating. Maximum differences in the natural frequencies are reduced from 21% to 8%, and good agreement is found between analytical and experimental natural frequencies. In addition to this, it is realized that finite element model updating is effective on the earthquake behaviour of the minaret. Copyright © 2008 John Wiley & Sons, Ltd.

Hong, Won‐Kee; Park, Seon‐Chee; Kim, Jin‐Min; Lee, Seung‐Geun; Kim, Seung‐Il; Yoon, Ki‐Joon; Lee, Ho‐Chan

doi: 10.1002/tal.485pmid: N/A

An experimental investigation of composite beams composed of wide flange steel and precast concrete is presented. The bottom flange of the steel section is encased in precast concrete. Utilizing the merits of both steel and concrete material, the size of the steel beams can be reduced without sacrificing performance. The bottom flange of the steel beam is reinforced with concrete at a manufacturing plant, eliminating the use of temporary pour forms. The composite beams were tested to investigate how the size of the wide flange steel and how the top and bottom reinforcements influence the behaviour of the beams. Flexural load carrying capacity, load displacement relationships and failure modes were examined. The test specimens were T‐shaped composite beams with slabs, each measuring 10‐m long. The flexural moment strength of all of the composite beams—at both the yield limit state and the maximum load limit state—was measured and compared with the analytical flexural capacity. The stiffness degradation, ductility and dissipating energy capabilities of the composite beams were investigated based on the hysteresis curves. The composite beams tested in this study successfully reduced both the floor height of the building and the size of the steel beams needed to meet code requirements. Copyright © 2008 John Wiley & Sons, Ltd.

Poursha, Mehdi; Khoshnoudian, Faramarz; Moghadam, A. S.

doi: 10.1002/tal.487pmid: N/A

The nonlinear static pushover analysis technique is mostly used in the performance‐based design of structures. However, the pushover analysis with load distributions of Federal Emergency Management Agency (FEMA) loses its accuracy in estimating the seismic responses of long‐period structures where higher mode effects are important. Recently, modal pushover analysis (MPA) has been proposed to consider these effects. Hence, FEMA load patterns and MPA are evaluated in the current study and compared with inelastic response history analysis. These approximate procedures are applied to medium‐rise (10 and 15 stories) and high‐rise (20 and 30 stories) buildings; advantages and limitations of them are elaborated. It is shown that MPA procedure presents significant advantage over FEMA load distributions in predicting story drifts. MPA is able to compute hinge plastic rotations better than FEMA load distributions at upper floor levels of high‐rise buildings due to considering higher mode effects by this procedure, but both are unsuccessful in predicting hinge plastic rotations with acceptable accuracy. Copyright © 2008 John Wiley & Sons, Ltd.

Hart, Gary C.; Hortacsu, Ayse; Simsir, Can; Jain, Anurag

doi: 10.1002/tal.491pmid: N/A

A wealth of data has become available since 2001 about the performance of drywall shear walls under cyclic loading. Drywalls and stucco are the only earthquake lateral force‐resisting system in many existing residential buildings, especially single‐family homes built in the 1970s and earlier. This paper takes a closer look at the actual laboratory cycle‐by‐cycle data from three test programs and uses them to clarify the meaning of significant damage in regard to gypsum‐sheathed shear walls. This paper can be viewed as an extension of the valuable information in the reports by the original authors with a focus on the interpretation and use of the test data for the evaluation of damage to existing wood‐frame buildings. Analysis of the data considers the strength loss observed between the initial and later cycles when the wall is loaded to a certain displacement and shows that a loss of strength does occur. In this regard the paper can also be valuable to others working on performance based design development. The last section of the paper also considers the case where a wall might be repaired after the first cyclic loading protocol and loaded again after the repairs. Copyright © 2008 John Wiley & Sons, Ltd.

Moon, Kyoung Sun

doi: 10.1002/tal.499pmid: N/A

This paper investigates the structural performance of vertically distributed multiple tuned mass dampers (MTMDs), which can save valuable occupiable space near the top of tall buildings, control the first as well as higher mode responses and be installed more easily because of smaller tuned mass damper (TMD) masses. Vertically distributed MTMD theory is presented. With this theory, the effectiveness of vertically distributed MTMDs along the building height is predicted using simplified models, compared with the conventional TMDs installed near the top of tall buildings. Vertically distributed MTMDs are designed for a typical 60‐storey tall building subjected to representative dynamic wind loads, and their performance is measured. The results of these studies show that TMDs can be distributed vertically along the building height without substantial loss of their effectiveness. Considering their advantages over the conventional system, vertically distributed MTMDs possess a high potential of practical applications for tall‐building motion control. Copyright © 2009 John Wiley & Sons, Ltd.