Tuan Norhayati Tuan Chik

Analysis of the effect of vibration from footfalls on office building

Human footfalls are the main source of vibration in office building and it could affect the structure of the building as well as causing discomfort and annoyance to the occupants of the building when the vibration level inside the building exceeds the recommended level. The objectives of the study are to determine the level of vibration on each floor of a multi-storey building due to footfalls and to perform structural response on the multi-storey building due to footfalls input. The selected building for this study is Registrar Office building located in Universiti Tun Hussein Onn Malaysia (UTHM). The scope of study is focused on the effect of vibration induced by footfalls on multi-storey building and analyzing the data using MATLAB and ANSYSv14. The real inputs of vibration induced by footfalls were measured and obtained using Laser Doppler Vibrometer (LDV). The vibration level induced by footfalls on the multi-storey office building can be determined using Vibration Criteria (VC) guidelines. Finally, from the study, the vibration level achieved for this Registrar Office building is in ISO level range which is still under the acceptable limit for office building.

Soil-roots Strength Performance of Extensive Green Roof by Using Axonopus Compressus

Green roof technology has been proven to provide potential environmental benefits including improved building thermal performance, removal of air pollution and reduced storm water runoff. Installation of green roof also involved soil element usage as a plant growth medium which creates several interactions between both strands. This study was carried out to investigate the soil-roots strength performance of green roof at different construction period up to 4 months. Axonopus compressus (pearl grass) was planted in a ExE test plot with a designated suitable soil medium. Direct shear test was conducted for each plot to determine the soil shear strength according to different construction period. In addition, some basic geotechnical testing also been carried out. The results showed that the shear strength of soil sample increased over different construction period of 1st, 2nd, 3rd and 4th month with average result 3.81 kPa, 5.55 kPa, 6.05 kPa and 6.48 kPa respectively. Shear strength of rooted soil samples was higher than the soil samples without roots (control sample). In conclusion, increment of soil-roots shear strength was due to root growth over the time. The soil-roots shear strength development of Axonopus compressus can be expressed in a linear equation as: y = 0.851x + 3.345, where y = shear stress and x = time.

Ground Vibration Attenuation Measurement using Triaxial and Single Axis Accelerometers

Peak Particle Velocity is one of the important term to show the level of the vibration amplitude especially traveling wave by distance. Vibration measurement using triaxial accelerometer is needed to obtain accurate value of PPV however limited by the size and the available channel of the data acquisition module for detailed measurement. In this paper, an attempt to estimate accurate PPV has been made by using only a triaxial accelerometer together with multiple single axis accelerometer for the ground vibration measurement. A field test was conducted on soft ground using nine single axis accelerometers and a triaxial accelerometer installed at nine receiver location R1 to R9. Based from the obtained result, the method shows convincing similarity between actual PPV with the calculated PPV with error ratio 0.97. With the design method, vibration measurement equipment size can be reduced with fewer channel required.

Dynamic Analysis of an Office Building due to Vibration from Road Construction Activities

Construction activities are widely known as one of the predominant sources of man-made vibrations that able to create nuisance towards any adjacent building, and this includes the road construction operations. Few studies conclude the construction-induced vibration may be harmful directly and indirectly towards the neighbouring building. This lead to the awareness of study the building vibration response of concrete masonry load bearing system and its vibrational performance towards the road construction activities. This study will simulate multi-storey office building of Sekolah Menengah Kebangsaan (SMK) Bandar Enstek at Negeri Sembilan by using finite element vibration analyses. The excitation of transient loads from ground borne vibrations which triggered by the road construction activities are modelled into the building. The vibration response was recorded during in-situ ambient vibration test by using Laser Doppler Vibrometer (LDV), which specifically performed on four different locations. The finite element simulation process was developed in the commercial FEA software ABAQUS. Then, the experimental data was processed and evaluated in MATLAB ModalV to assess the vibration criteria of the floor in building. As a result, the vibration level of floor in building is fall under VC-E curve which was under the maximum permissible level for office building (VC-ISO). The vibration level on floor is acceptable within the limit that have been referred.

Vibration Analysis of Beam and Block Precast Slab System due to Human Vibrations

Beam and block precast slabs system are very efficient which generally give maximum structural performance where their voids based on the design of the unit soffit block allow a significant reduction of the whole slab self-weight. Initially for some combinations of components or the joint connection of the structural slab, this structural system may be susceptible to excessive vibrations that could effects the performance and also serviceability. Dynamic forces are excited from people walking and jumping which produced vibrations to the slab system in the buildings. Few studies concluded that human induced vibration on precast slabs system may be harmful to structural performance and mitigate the human comfort level. This study will investigate the vibration analysis of beam and block precast slab by using finite element method at the school building. Human activities which are excited from jumping and walking will induce the vibrations signal to the building. Laser Doppler Vibrometer (LDV) was used to measure the dynamic responses of slab towards the vibration sources. Five different points were assigned specifically where each of location will determine the behaviour of the entire slabs. The finite element analyses were developed in ABAQUS software and the data was further processed in MATLAB ModalV to assess the vibration criteria. The results indicated that the beam and block precast systems adequate enough to the vibration serviceability and human comfort criteria. The overall vibration level obtained was fell under VC-E curve which it is generally under the maximum permissible level of vibrations.

Vibration Response of Multi Storey Building Using Finite Element Modelling

Interaction between building, type of foundation and the geotechnical parameter of ground may trigger a significant effect on the building. In general, stiffer foundations resulted in higher natural frequencies of the building-soil system and higher input frequencies are often associated with other ground. Usually, vibrations transmitted to the buildings by ground borne are often noticeable and can be felt. It might affect the building and become worse if the vibration level is not controlled. UTHM building is prone to the ground borne vibration due to closed distance from the main road, and the construction activities adjacent to the buildings. This paper investigates the natural frequency and vibration mode of multi storey office building with the presence of foundation system and comparison between both systems. Finite element modelling (FEM) package software of LUSAS is used to perform the vibration analysis of the building. The building is modelled based on the original plan with the foundation system on the structure model. The FEM results indicated that the structure which modelled with rigid base have high natural frequency compare to the structure with foundation system. These maybe due to soil structure interaction and also the damping of the system which related to the amount of energy dissipated through the foundation soil. Thus, this paper suggested that modelling with soil is necessary to demonstrate the soil influence towards vibration response to the structure.

Analysis of Vibration Effects on Floor of Office Building due to Ground Vibrations from Passing Vehicles

Since the earliest days of ground road transportations and constructions in urban areas, there have been complaints of vibration in building caused by this external source of vibration, known as ground borne vibration. Vibration when it exceeds the recommended threshold could affect the structure of the building and any sensitive equipment housed inside the building, as well as causing discomfort and annoyance to the occupants of the building. The objectives of the study are to determine the level of vibration on each floor of a multi storey building due to ground borne vibration from road traffic, second to numerically investigate the structural response on the multi storey building from vehicles, and lastly to assess the vibration response obtained from both vehicles with the vibration criteria guideline. The selected building for this study is Registrar Office building located in Universiti Tun Hussein Onn Malaysia (UTHM). The scope of study is focused on the effect of ground borne vibration from vehicles on multi storey building and analyzing the data using MATLAB and ANSYSv14. The real inputs of vibration from vehicles were measured and obtained using Laser Doppler Vibrometer (LDV). The vibration level from vehicles and footfalls on the multi storey office building can be determined using Vibration Criteria (VC) guidelines by Gordon. Finally, from the study, the vibration level achieved for this Registrar Office building is above the ISO level which is exceeds the acceptable vibration limit for office building.

Floor Dynamic Assessment on Laboratory due to Ground Borne Vibrations Using ModalV Analysis from Passing Vehicles

High-tech development on laboratory with high resolution and sensitive device is increased nowadays. This equipment requires very sensitive location to accommodate in a special room, because it may cause improper functioning for a certain devise which required low level of vibration. Due to this problem, the aim of this study are to perform the structural response on two story laboratory subjected to ground vibration input due to traffics and to assess the level of vibration at the floor. The vibrations input are measured by using portable equipment called Laser Doppler Vibrometer. The field measurement is done at the laboratory Block E, Faculty of Mechanical and Manufacturing Engineering at Universiti Tun Hussein Onn Malaysia (UTHM). Finite element ANSYS software is fully utilized to model the building structure and perform analysis in order to determine structural modal and transient analysis for the building. Time history response from ANSYS post-processing is transferred into ModalV analysis in MATLAB software in order to evaluate the vibration criteria level of the floor according to specific overseas guideline. It was found that the vibration response on the middle slab of the first floor at level Vibration Criteria, VC-A or maximum particle velocity level at 50μm/s. Vibration Criteria (VC) curve analysis on floor slab indicated the highest vibration will occur at the middle of floor slab and the lowest vibration will occur at the edge of slab which near the column and below VC-E level for ground floor slab.

Influence of People Walking on Floor Performance due to Low Level Vibration

Abstract. Vibration in building is one of the important problems which need to consider, especially in designing the floor. Floor vibrations are generally caused by dynamic loads applied particularly by human activity especially walking. Although it is specified as low level amplitude, walking induced vibrations can cause discomfort to human occupants and alarming for a certain items of precision sensitive equipment. This paper investigates the vibration response on floor performance due to one, three and five of people walking. Laser Doppler Vibrometer was used to obtain vibration data when people are walking. Further analysis was carried out by using finite element software package ANSYS to simulate the floor under vibration inputs to obtain natural frequency and mode shapes of the floor structure. The vibration data was then analysed in ModalV analysis to generate the vibration response. Then, the results were checked against the vibration criteria level guideline as a crude tool comparison. As a result, the numbers of people walking were influenced the floor performance, which indicated five peoples walking show the highest response up to ISO level due to vibration compared with one people walking.

Vibration Response on MiNT-SRC Building due to Ground Borne Vibrations From Humans Using Finite Element Modeling

Building structure is naturally exposed to the vibration phenomenon. Vibration in high amplitude may causes big damages to the building structure, while the lower amplitude of vibrations is not causes big effect to the building but it may produce low vibration response to floor structure that can disturbance people comfort and equipment workability. In this study, the vibration response is focusing on low amplitude of vibrations from the ground which due to human activity like footstep or walking. Human activity such as walking will produce low vibration amplitude that can affect the sensitivity of sensitive equipment inside the research or laboratories facilities. Microelectronic and Nanotechnology-Shamsuddin Research Center (MiNT-SRC) building at UTHM is selected to be a location for ground borne vibration measurement due to human activities. The research center is chosen due to sensitivity equipment in the building that prone to vibration effect. Finite element modelling is the method been used to analysed the vibration response distribution to overall building. Vibration data input from field measurement is analysed in ANSYS software based on finite element method, and then further analysis in MATLAB software. A ModalV analysis program in MATLAB is used to produce one third octave velocity spectra and vibration criterion curve for the studied floor. The study shows that the vibration criterion for MiNT-SRC building is classified as VC-E at ground floor and VC-B at the first floor. Thus, based on the result analysis, the sensitive equipment is most suitable to locate at the ground floor of MiNT-SRC building.