Model Updating of a Full-Scale Building Structure Under Train Induced Vibration

Structure health monitoring (SHM) system is a method of monitoring and evaluation of structural health. Finite element method is extensively use to model the dynamics properties of a structure as it is believed to be an authentic tool for providing accurate results. To adopt a more precise dynamic properties of a structure, model updating technique involve updating a finite element model of a structure. However, due to many imaginary assumptions in the finite element (FE) model generation, the practical behaviour of full-scale structures contradicts the model results. It may be due to uncertain boundary conditions, poorly defined material properties of the structure or because of the simplified modeling of complicated structural systems. In this paper, six storey frame structure building has been investigated for dynamic model updating. The building was subjected to train induced excitation. Four accelerometers were employed to measure the response. Manual updating of building FEM model is carried out as per design parameters of the finite element model (elastic modulus and boundary constraints) to diminish the inconsistencies between the field measurement and the results of finite element model. For the subject building the supposition of semi-rigid joints (rotational area springs) can most precisely depict the dynamic properties of the subject building. The modified parameters obtained from the updated model are logical having meaningful interpretation

Recycling of Steel Scraps as a Strength Enhancement Material in Concrete

The cement industry is very energy consumptive and produces CO2 and also generates greenhouse gases which are the major cause of global warming. The production of cement and the use of concrete are both rising daily. So, to protect the environment, alternate materials are required. The construction industry has several constructional byproducts and wastes as a variant of traditionally used products. In the process of production and working with steel, steel chips are formed as waste material. The best way to reduce environmental pollution and improve waste recycling is to partially replace concrete with steel chips. Due to these factors and the abundance of material, steel chips were used as a partial cement replacement at 0.5%, 1%, 1.5%, and 2% by the volume of cement. The properties such as compressive strength, split tensile strength, flexural beam strength, and modulus of elasticity are checked after 7, 14, and 28 days. Comparing these qualities to those of control molds showed that by raising the percentage of steel chips in the concrete up to 1.5%, mechanical characteristics are improved; however, when the percentage is increased to 2%, mechanical properties are also affected

Experimental Study on Seismic Response Characteristics of Soil On Building Models Using 1-D Shake-Table.docx

ABSTRACT. This research investigates the impact of seismic response on the scaled 1:10 multi storey steel frame-model supported by isolated shallow footings placed on sand sample. One dimensional shake-table testing was carried out on four, three and two storeys steel Frame Model subjected to El-Centro 0.46pga Earthquake. Dynamic properties acceleration, displacement, natural frequency of the frame models on isolated footing with changing of storey height were measured. Moreover, it was found that acceleration responses and natural frequencies decreased with an increase in frame model height while displacement responses increased for a given foundation type with increased height. In conclusion, soil, the structure's height, and the materials properties all affect a structures seismic response during an earthquake

Experimental investigation of mechanical and microstructural properties of concrete containing bentonite and dolomite as a partial replacement of cement

In this study, the effect of bentonite (BT) and dolomite (DT) on the mechanical and microstructural properties of concrete was evaluated on nine mixes. Cement was replaced with bentonite and dolomite by weight with varying mix ratios. The mixes are divided as M1 (Control mix), M2 (2.5% BT), M3 (2.5% DT), M4 (5% BT), M5 (5% DT), M6 (10% BT), M7 (10% DT), M8 (2.5% BT and 2.5% DT), and M9 (5% BT and 5% DT). Concrete specimens were subjected to mechanical and microstructural analysis tests. Mechanical test results show that the addition of bentonite (2.5%, 5%, and 10% ) leads to an increase in compressive strength (6.31%, 8.94%, and 13.15%) respectively. Similarly, the addition of 2.5% and 5% dolomite enhanced compressive strength by 10.52%, and 8.94% respectively, however, the addition of 10% dolomite reduced compressive strength by 6.8%. Replacement of cement with dolomite and bentonite individually also showed a small contribution to flexural and split tensile strength. Microstructural analysis shows that the addition of bentonite and dolomite filled the microstructure and refined the internal pores contributing to compressive strength. In addition, the replacement of cement with bentonite and dolomite enhanced the formation of CSH gel.Keywords: Bentonite; dolomite; mechanical properties; microstructural analysi

Urgency for surgical evacuation of post traumatic Intracranial acute epidural hematoma

Introduction: Intracranial epidural haematoma, (EDH) is a collection of blood between the skull and dura mater due to head injury. It is considered to be the most serious complication of head injury requiring immediate diagnosis and surgical intervention. Background: The aim of our study was to present the outcome of consecutive patients with Acute EDH managed surgically & to prove the high risk of death or permanent brain damage without prompt surgical intervention. Method: In this study we retrospectively examined all consecutive head injury cases managed between September 2014 & September 2015 and diagnosed with acute traumatic epidural hematoma in isolation or in combination with intra cranial lesions. Age, sex, mechanism of injury, time of presentation, Glasgow Coma Score (GCS), pupil reactivity, time of surgery and clinical outcomes were evaluated. Results: Out of 31 cases 87%, (n=27) were males and 13 %,( n=4) were females. The mean age was 17.75 years. 74% (n=23) patients under the age of 25years. The most common mode of injury was road traffic accident 48%, (n=15) followed by fall 42%, (n=13). The mortality rate was 6% (n=2). The time interval between trauma & operation of both patients who died were more than 8 hours. Conclusions: An acute epidural hematoma is an emergency condition, the diagnosis of the EDH must be promptly made by CT scan and the patient should be immediately transferred into a neurosurgical centre, Early surgical intervention is associated with the best outcome

Finite element modeling of active cracking in actively reinforced concrete pavement slab exposed to fluctuating temperature

Abstract The continuously reinforced concrete pavement (CRCP) system grapples with challenges such as non-uniform transverse crack patterns and the need for substantial reinforcement. Field research on the Belgian CRCP sections along motorway E313 indicates that active cracking induced by partial surface saw-cuts consistently leads to transverse crack patterns. This study introduces an innovative modification to the CRCP: the actively reinforced concrete pavement design (ARCP). The ARCP leverages partial surface saw-cuts to reduce reinforcement needs by replacing continuous-length steel bars with partial-length counterparts. The main objective of the present study is to develop a 3D finite element (FE) model capturing the active cracking behavior of ARCP under realistic external temperature variations. Comparative analysis with CRCP considers early-age crack patterns, crack strain development, and the distribution of maximum steel stress for different steel ratios (0.67%, 0.75%, and 0.85%). FE simulation results align with field data, indicating that ARCP exhibits similar early-age cracking behavior to CRCP but with a significant 24 to 42% reduction in total reinforcement. This innovation presents a promising avenue for addressing CRCP challenges while optimizing material usage in pavement construction

Enhancing multi-objective mix design for GGBS-based geopolymer concrete with natural mineral blends under ambient curing: A Taguchi-Grey relational optimization

Rising populations and industrial expansion necessitate sustainable alternatives to conventional cement-based concrete. Geopolymers, with their impressive mechanical properties, eco-friendliness, and potential for waste utilization, offer a promising solution. Yet, concerns like rapid setting and low workability limit their widespread adoption. This study addresses these challenges by optimizing a geopolymer concrete incorporating ground granulated blast furnace slag (GGBS) blended with bentonite and dolomite minerals. Employing the Taguchi method, we optimized the mix design considering key factors like binder content, mineral replacements, alkaline-to-binder ratio, and solution ratios. Grey-Relational Analysis identified the optimal mix with 10 % bentonite and dolomite replacement, a 0.55 alkaline-to-binder ratio, 12 M NaOH solution, and 425 kg/m3 cementing materials. This optimized mix exhibited significantly improved setting times, enhanced workability, and the highest compressive strength among all tested mixtures. Experimental validation confirms its effectiveness, highlighting its potential as a sustainable alternative. Importantly, this research explores GGBS as a replacement for commonly used Fly Ash, further advancing sustainable construction practices