MATLAB for All Steps of Dynamic Vibration Test of Structures

With the recent advances in computer technology and digital simulation software, it is now possible to rapidly and accurately build computer models for complex linear and nonlinear dynamic systems. MATLAB is a unique system that can be used for structural and earthquake engineering problems. This study presents MATLAB tools developed for numerical process of all steps of dynamic vibration test of structures. The functions of the tools are processing the signals obtained from forced and ambient vibration tests of structures, determining the dynamic characteristics of structural systems, and automatically updating the analytical finite element (FE) models. The software group is composed of three programs named as SignalCAD, ModalCAD, and FemUP. The SignalCAD program is developed for processing raw measured data obtained from forced and ambient vibration tests of engineering structures. The ModalCAD program is developed for dynamic characteristic identification and validation procedure. The peak picking method, complex exponential method, and polyreference time domain method are used for modal identification process. The FemUP program is developed for automatically updating the numerical models of structures compared to modal testing results. Each program has a unique graphical user interface and is designed as user friendly. The possibilities of the programs are demonstrated with the model vibration test of a steel cantilever beam. The obtained results are compared to the analytical model, and the FE model is automatically updated, whereas the experimental model is considered as the reference model. Finally, it is seen that MATLAB can be used as a scientific programming platform in all vibration test and modal analysis applications

Ambient Vibration Based Model Updating Effects on the Earthquake Response of Tall Buildings

The study investigates ambient vibration based model updating effects on the seismic behaviour of a RC tall building subjected to far and near-fault ground motions. A 17-storey building built in Giresun, Turkey is selected as an application. Firstly, 3D initial finite element model of the selected building is created and determined analytical dynamic characteristics. Then, experimental dynamic characteristics of the building (frequencies, mode shapes, damping ratios) are determined by Operational Modal Analysis Method from the ambient vibration tests. According to experimental results, initial finite element model is calibrated by using boundary conditions and material properties. Initial and calibrated finite element models of the building are analysed under far and near-fault ground motions. The displacements, velocity and accelerations from the analyses are compared with each other

Seismic analysis of arch dams subjected to in-phase and anti-phase ground motions

In this study, the response of arch dams is obtained for in-phase and anti-phase ground motions when there is no water in the reservoir. The material of the dam is considered to be linearly elastic, homogenous and isotropic. The foundation and banks of the dam, which are usually of hard rock, are assumed to be rigid. The S16E component of San Fernando Earthquake, February 9, 1971, has been used in the calculations. The response of arch dams determined for anti-phase dynamic effects is compared with that of in-phase (uniform) dynamic effects

Restoration Effects on the Experimental Dynamic Behavior of Historical Molla Siyah Mosque

The effects of restoration on the experimental dynamic characteristics of historical masonry Molla Siyah Mosque in Trabzon, Turkey, are investigated in this paper. Firstly, the initial situation and the implemented restoration works of the mosque are mentioned in detail. Then, the experimental dynamic behaviors of the mosque before and after the restoration are obtained by using the Ambient Vibration Tests. High sensitivity seismic accelerometers with cables are used during the tests. The collected signals are evaluated by Enhanced Frequency Domain Decomposition Technique, and experimental natural frequencies, mode shapes and damping ratios of the mosque are determined for the initial and restoration cases. The obtained results are compared with each other and restoration effects on the dynamic behavior of the mosque are discussed in detail

Finite Element Analysis and Ambient Vibration Test of the Arch Type Steel Highway Bridges

In this paper, it is aimed to determine the dynamic characteristics of highway bridges using finite element analyses and ambient vibration tests. A modern steel highway bridge which has arch type structural system with 216 m total length and located in the Ayvacik county of Samsun, Turkey is selected as an application. Because of the fact that the bridge connects the villages which are separated with Suat Ugurlu Dam Lake, it has a major logistical importance for this region. The construction of the bridge is completed in 2009 and opened the traffic. An analytical modal analysis is performed on the developed 3D finite element model of the highway bridge to provide the analytical frequencies and mode shapes. The experimental measurements are carried out by ambient vibration tests under traffic loads. Vibration data are gathered from bridge deck. Measurement time, frequency span and effective mode number are determined by consider similar studies and literature. Enhanced Frequency Domain Decomposition method in the frequency domain and Stochastic Subspace Identification method in the time domain are used for the output only modal identification and dynamic characteristics such as natural frequencies, mode shapes and damping ratios are determined, experimentally. At the end of the study, analytically and experimentally identified dynamic characteristics are compared with each other. A good agreement is found between mode shapes, but some difference in natural frequencies

Shear strain related non-linear stochastic dynamic analysis of rock-fill dams

The effect of the non-linear material behavior of a rock-fill dam subjected to random loads is investigated by the equivalent linear method that considers the non-linear variation of soil shear moduli and damping ratios as a function of shear strain. The Keban dam constructed in Elazığ, Turkey is chosen as a numerical example. The interaction of the rock-fill dam with the reservoir is neglected, but not the foundation rock. The properties of the dam materials were taken from the dam project and assumed to be isotropic in the analysis. A stationary and ergodicity assumption are made for stochastic dynamic analysis. The E-W component of the Erzincan earthquake recorded on March 13, 1992, Erzincan, Turkey is chosen as a ground motion since it occurred nearby the dam site. The component considered is applied to the dam in the horizontal direction. The non-linear stochastic responses of the Keban dam are compared to its linear stochastic and deterministic response

Monitored structural behavior of a long span cable-stayed bridge under environmental effects

An accurate numerical analysis of the behavior of long-span cable-stayed bridges under environmental effects is a challenge because of complex, uncertain and varying environmental meteorology. This study aims to investigate in-situ experimental structural behavior of long-span steel cable-stayed bridges under environmental effects such as air temperature and wind using the monitoring data. Nissibi cable-stayed bridge with total length of 610m constructed in the city of Adıyaman, Turkey, in 2015 is chosen for this purpose. Structural behaviors of the main structural elements including deck, towers (pylons) and cables of the selected long span cable-stayed bridge under environmental effects such as air temperature and wind are investigated by using daily monitoring data. The daily variations of cable forces, cable accelerations, pylon accelerations and deck accelerations with air temperature and wind speed are compared using the hottest summer (July 31, 2015) and the coldest winter (January 1, 2016) days data

Experimental Dynamic Characteristics of Historical Masonry Stone Mosques with Wooden Roof

Ahşap çatılı doğal taş yığma camiler, Türkiye’nin Doğu Karadeniz Bölgesinde sıklıkla rastlanan tarihi eserlerdendir. Camilerin beden duvarları doğal taş, kireç, toprak veya horosan harcı birleşimi ile yapılmış ve çatıları ahşap elemanlarla teşkil edilmiştir. Bu çalışma kapsamında, Doğu Karadeniz Bölgesinde bulunan ahşap çatılı yığma taş camilerin dinamik karakteristiklerinin hasarsız deneysel yöntemlerle tespit edilmesi amaçlanmıştır. Uygulama amacıyla, Rize Gülbahar Mahallesi Büyük Camii, Artvin-Hopa Sundura Mahallesi Camii ve Trabzon Merkez Tavanlı Camii seçilmiştir. Seçilen camiler, yakın zamanda restorasyonu yapılmış eserler olup, geometrileri ve özelikleri benzerdir. Camilerin frekans, sönüm oranı ve mod şeklinden oluşan dinamik karakteristikleri sismik ivme ölçerler kullanılarak Çevresel Titreşim Testi yöntemiyle belirlenmiştir. Söz konusu camilerden elde edilen hasarsız deneysel sonuçlar birbirleriyle karşılaştırılmış ve ahşap çatılı yığma camilerin analitik modellerinin kontrolü için frekans aralığı verilmiştir.Natural stone masonry mosques with wooden roof are the most widespread historical building of Eastern Black Sea Region in Turkey. The main walls of buildings are made with the combination of natural stone, lime, soil or horosan mortar and their roofs are constituted with wooden elements. Within the scope of this study, it is aimed to determine the dynamic characteristics of masonry stone mosques with wooden roof in the Eastern Black Sea Region in Turkey with nondestructive experimental methods. For the purpose of practice, Rize Gulbahar Mahallesi Buyuk Mosque, Artvin Hopa Sundura Mahallesi Mosque and Trabzon Merkez Tavanlı Mosque are selected. Selected mosques have recently been restored and their geometries and properties are similar. The dynamic characteristics such as natural frequency, modal damping ratios and mode shape of the mosques are determined with the Ambient Vibration Test by using the seismic accelerometer. The results of nondestructive experiments obtained from the mosques are compared with each other and the frequency interv

The Comparison of Experimental Dynamic Behavior of Historical Mosques with Masonry and Reinforced Concrete Do

..

Simplified Earthquake Analysis of Suspensi

This paper presents the finite element analysis of a suspension bridge subjected to earthquake ground motion using simplified models. For this purpose, two simplified models are considered. It is assumed that each element compose of the deck, cable and hangers in the first model. As second model, the elastic foundation analogy method is used. Also, actual bridge model is selected. Finite element earthquake analyses of the simplified and real bridge models are performed. One of the world's longest modern type suspension bridges, Fatih Sultan Mehmet Bridge, is selected as a numerical example. As ground motions, Kocaeli earthquake occurred on August 17, 1999 in Kocaeli, Turkey is chosen since it took place at the vicinity of the bridge. The response values obtained from simplified and actual bridge models are compared with each other