Full dynamic analysis of Tehran telecommunication tower; linear and nonlinear responses

The performance study of high-rise towers has been attracting attention recently. Powerful analysis methods are used to assess local and global behaviour of tall structures. Incremental Dynamic Analysis (IDA) is one the most powerful methods for accurate estimation of seismic performance of structures.In this paper, IDA is applied on high-rise towers, specifi cally Tehran telecommunication tower. Three different fi nite element models have been developed. The fi rst model is a two-dimensional fi bre beam element model on which IDA is applied. The other two models are fi nely meshed three-dimensional elastic and inelastic multiaxial-element-based models, which are used to investigate the validity of the two-dimensional model. Furthermore, the effi ciency of different Intensity Measures and Engineering Demand Parameters is investigated. The results show that there is a good agreement between the results of two-dimensional and three-dimensional models in linear and nonlinear domains. It is also observed that Sa(T1) is more effi cient than peak ground acceleration (PGA) as spectral acceleration is a structural specifi c intensity measure in comparison with, which is site-specifi c. Elastic modelThe elastic model computations were performed using the commercial fi nite element software package ANSYS. The mat footing is modelled using eight-node shell elements with constant thickness of 3 m. The transition structure with its openings is modelled using 20-node solid and 8-node shell elements. Shell elements with variable thickness are used to model shaft walls. Members of the head structure are modelled by three-node beam elements, and fi nally, the antenna is modelled through the use of pipe elements. The fi nite element model of the tower is shown in Figure 4.

Section: Introductionmentioning

confidence: 99%

Incremental dynamic analysis of high‐rise towers

Asgarian

Yahyai

Mirtaheri

et al. 2010

“…They concluded that this method can accurately predict the frequency-dependent dynamic characteristics of the reinforced concrete tower. Khaloo et al (2001) studied the linear and nonlinear responses of Milad Tower using three different fi nite element models. Cracking and crushing of the reinforced concrete material and large deformation effects were considered in their study.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear seismic response of Milad Tower using finite element model

Yahyai

Rezayibana

Daryan

2008

Milad Tower is a 436-m-tall telecommunications tower ranked as the fourth tallest structure of its kind in the world. The study of its seismic behaviour is of great importance as it is located in a highly seismic-prone region. Because of the existence of the world's largest revolving restaurant in the head structure, and also because of the highly sensitive communication devices such as TV and telecommunications antennas installed on the tower, nonlinear deformation under future earthquakes should be studied. In this paper, a detailed fi nite element model is developed and nonlinear dynamic analysis was carried out under the design earthquakes. The foundation, concrete shaft, head structure and 120-m antenna structure were modelled. Three components of the earthquakes are considered, and the selected earthquakes were normalized based on three design levels: design basis level, maximum design level and maximum credible level. The results of the analysis showed that all parts of the tower behave in the plastic zone except the elements of the head structure. It is also observed that in some cases, the earthquakes with lower peak accelerations and higher energy contents may have more severe effect on the tower than that with higher peak accelerations. triangular and inclined walls, respectively. Three-dimensional truss elements are used for modelling the post-tension tendons that are embedded in the exterior ring of the circular foundation. Reinforcements are accurately placed in the fi nite element model according to the structural drawings.Four-node shell elements are used from the height level of 0.0 m to the height level of 307 m, where the section of the shaft is changed to accommodate the antenna mast. Eight-node solid elements are used above the height level of 307 m for modelling the concrete shaft. The concrete shaft is modelled accurately with every structural part.All members of the head structure are modelled using a 3-D Bernoulli-Euler beam, in which the shear deformation is ignored. To consider the fl oor rigidity, all of the nodes are tied together in every storey to have equal movements (equal transition in the X and Y directions and equal rotation about the Z-axis.Four-node shell elements are used for modelling the antenna mast, and the stiffeners are modelled by 3-D Bernoulli-Euler beam elements. This part is also modelled completely. The fi nite element of the tower is shown in Figure 4. It should be mentioned that the fi nite element model consists of 13 284 elements and 17 920 nodes. MATERIAL MODELLINGThe materials used in the structure are mainly steel and concrete, and convenient models are used to defi ne the behaviour using the ABAQUS software (ABAQUS, 2006). Figure 3. The head structure of Milad Tower 882 M. YAHYAI, B. REZAYIBANA AND A. SAEDI DARYANThe isotropic trilinear steel model is used for high-strength steel, and the isotropic bilinear steel model is used for tendons and high-strength bars that do not have a plastic plateau (Table 1). ConcreteThe 28-day compressive strength of the con...

“…Moreover, the response spectrum can be used as basic data to compare with future acquisitions to discover structural damage to the structure due to the passage of time or particular events (such as an earthquake) (Zonta et al, 2000;Khaloo et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

An experimental and numerical approach to investigate the dynamic response of a four‐flue chimney of a thermo‐electrical plant

Cavacece

Valentini

2003

This paper describes an experimental procedure and a numerical model for the study of the dynamic behaviour of a chimney of a thermo-electrical plant. The experimental part is based on the measurement of the structure's dynamic response by means of several accelerometers. Different signals from forced time-periodic excitations, spanning a range of frequencies, have been collected and compared with those from a finite elements model. In particular, the first four modal shapes and their frequencies are computed. Following this validation, the finite element model has also been applied to investigate the response of the chimney subjected to a generic wind periodic excitation (vortex shedding). The numerical results show good agreement with the experimentally collected data.• Four internal flues, with a diameter of 5·0 m each, made of acid-repellent and insulated bricks. Each flue is divided into 10 portions of 17·0 m, except the highest one, which is substantially shorter, and THE STRUCTURAL DESIGN OF TALL AND SPECIAL BUILDINGS