Retrofitting of Confined Brick Masonry with FRP

Brick masonry structures are commonly used in world because of its simplicity and economy. However, it is susceptible to failure in earthquakes because of the bricks weak interlocking bonds and brick masonry structures designed mainly against gravity load demand. Therefore, in recent years research work has been conducted to confine the unreinforced brick masonry with reinforced concrete tie beams and column, to improve its seismic performance. This enhances both the lateral resistance and stability of the entire structure, to perform as one mass unit against the lateral forces. However, the effect of confining brick masonry through reinforced concrete member has been evaluated in the past only on testing single cantilever walls or single room. Therefore, this research work aims to evaluate its influence on large structures i.e., highlight its limitation and afterward mitigate the damages by introducing external FRP strengthening techniques. The structures configuration is based on the observation made in Pakistan’s rural areas where mostly brick masonry structure. Confined brick masonry walls are subjected to quasi static lateral loading, afterwards retrofitted with FRP and tested again. The test result discussion includes load response behavior, stiffness degradation, energy dissipation and damage indices. Keywords: Confined brick masonry, RC tie beam column, FRP, Retrofitting, Seismic analysis, Quasi Static

Analysis on the Leakage of the Flange Connection of the Water-Containing Hydrofluoric Acid Pipeline

Leakages of bolted pipe flange connections of water-containing hydrofluoric acid pipelines were frequently reported by the extraction section in the fluorine chemical industry. Water-containing hydrofluoric acid can cause severe injuries to human beings due to its strong causticity. The water-containing hydrofluoric acid pipe was a short lined pipe, so a lot of flange connections and supports were adopted in the pipeline. In this paper, the finite element models of the pipeline were established to analyze the internal force of the pipeline under conditions including internal pressure, temperature, self-weight, and so on. Based on this, the equivalent design pressure of the flange connections was determined. The results of the stress analyses of the pipeline showed that leakages were mainly caused by a large bending moment, due to the unreasonable layout of the piping supports under self-weight. When the pipeline was supported on the beam of the pipe gallery, which is not necessarily beneficial to reduce the bending moment of the pipeline, and the flange connection was close to the supporting beam at the same time, leakages frequently occurred in this flange connection. To support the pipeline reasonably, the flange connection should be placed at zero bending moment positions. Therefore, the positions with zero bending moments of the pipeline with equal and unequal spacing supports were obtained under gravity load, to provide a basis for the rational support of lining piping.

Simulation for Fitting the Bending Shape of Fruit Branches of Lycium barbarum Based on the Finite Element Method

The accurate modeling of wolfberry plant morphology is the basis for theoretical and simulation analyses of the wolfberry picking process. The curved shape of the fruit branches makes it challenging to model Lyciumbarbarum (wolfberry) plants. This paper establishes a three-dimensional model of the branches under no gravity through field measurements, and then assesses the morphology of the branches under gravity load, fruit load, and branch load using finite element simulation. An orthogonal rotation combination experiment determined the relationship between branch morphology, length, growth angle, and growth mode parameters. The p-values of the prediction model were 0.0001, 0.0067, and 0.0203, respectively. Finally, the bending shape of the actual branches was verified against the branches generated by the prediction model. The experimental results show that the prediction model accurately models the fruit-bearing branches of Lycium barbarum. This paper introduces a method to quickly predict the bending shape of fruit-bearing branches of Lycium barbarum, providing a theoretical basis for rapid modeling of the L. barbarum plant and a simulation analysis for its harvesting.

Seismic performance of strengthened masonry structures: actual behaviour of buildings in Norcia and Campi Alto during the 2016 Central Italy seismic sequence

The structural response of unreinforced masonry buildings designed for gravity load only or with reference to obsolete seismic provisions is widely studied in the literature in order to define proper strengthening strategies and solution to mitigate the seismic risk. However, the critical analysis of the effectiveness of past used strengthening solution is still lacking. To fill such gap, the present study deals with the evaluation of the seismic performances of buildings in Campi Alto struck by the 2016 central Italy seismic sequence. The behaviour of buildings in Campi Alto is compared with that of buildings in Norcia. A large part of the buildings in these two towns was strengthened between 1980 and 2000 during the reconstruction processes following previous earthquakes which occurred in 1979 and 1997. However, the strengthened buildings in Norcia reported limited damage while a significant and widespread level of damage was detected on several strengthened buildings in the hamlet of Campi Alto. This study focuses on the buildings in Campi Alto with the aim of investigating on the reasons of their unsatisfactory behaviour. Thus, the seismic action experienced by buildings in Norcia and Campi Alto is initially compared and the main vulnerabilities of these buildings are also evaluated. Then, 20 projects of strengthening interventions submitted to the Civil Engineering Department of the Umbria Region between 1984 and 2012 have been herein analysed and discussed in order to focus on the effectiveness of the strengthening solution adopted in the past. The analyses of such projects and of the empirical damage detected after the 2016 seismic sequence is a unique opportunity to derive useful information for future applications.

Comparison of Static and Dynamic Analysis of Multi-Storied Building

Vibration of ground is the main cause of earthquake damage to building structures. There are many factors responsible for the strength of earthquake shaking at a site including the earthquake's magnitude, the site's proximity to the fault, the local geology, and the soil type. The natural disasters have been fast recurring all over the world causing great concern and damage to man and their properties. Among these disasters Earthquake is an endogenous natural disaster, which occurs suddenly without any warning. The vast devastation of engineering systems and facilities during the past earthquakes has exposed serious deficiencies in the prevalent design and construction. Shear wall is one of the most commonly used lateral load resisting in high rise buildings. Shear wall can be used to simultaneously resist large horizontal load and support gravity load. In the study, one tall RCC building of 13 stories is assumed to be situated in seismic zone V is analysed using two methods (Static and Dynamic Analysis). The share walls are taken at different position of building. The comparison of the different shear wall models is studied in this work against the different parameters like time period, bending moment, shear force, storey drift, displacement

Strategies for Structural and Energy Improvement in Mid-Rise Unreinforced Masonry Apartment Buildings. A Case Study in Mestre (Northeast Italy)

Two-thirds of the Italian building stock was already built by the 1970s, largely according to gravity load design and using economical materials and poor workmanship. Currently, the structures, fixtures, and fittings of these buildings have reached the end of their service life, and they require both an assessment and an update to meet new standards and new needs. As an example of a common type, this article deals with the assessment of the present state and the proposal of an integrated structural and architectural intervention on an existing brick masonry mid-rise apartment building in the suburbs of Venice, Northern Italy. The structural analysis highlights a moderate vulnerability, despite the low seismic hazard, and the energy analysis indicates that the highest management costs are due to heating and sanitary uses. Low-impact strategies are preferred for each aspect of the required interventions. Their costs are counterbalanced by (a) the reduction to a fifth of the present management costs; (b) a 20% average increase in the economic value of the flats; and (c) a favorable tax regime at the national level. Transformed into parametric values, also useful for large scale analyses, these costs resulted in a sustainable monthly instalment from the owners, who may also benefit from the increased quality of the place where they live.

Optimization of Diagrid Angle for High Rise Structure for Varying Bay Widths

The development of urban population, the lack of space and the high land costs has created the scope and necessity for the high-rise structures. In high rise structures, the design of lateral load resisting systems is more crucial than gravity load resisting system. There are many structural systems exists in literature to resist lateral loads. Diagrid structure is one among them which is proven to be both structurally and architecturally efficient structural system to resist lateral loads. The present study aims to investigate the best bay spacing for a particular high-rise structure and also optimizing the best diagrid angle to suit to the selected bay spacing. A numerical study is carried out with a 24 storied high-rise structure of plan area 36m x 36m considering with and without corner columns. The structure performance is checked with a bay width of 4m and with a bay width of 6m. Each structure is analyzed for four angles of inclinations of diagrid are formed by connecting 1, 2, 3, 4 stories respectively to optimize the diagrid angle. A comparative investigation is carried out for the structural responses like storey displacement, storey drift and base shear with different diagrid angles and with different bay width.