Disaster Advances

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Disaster Advances

Performance of RC Space frame with vertical setback subjected to Seismic and Blast Load using Applied Element Method

Madisetti Pavan Kumar* and Koripella Rambabu

The response of any structure to a dynamic disturbance depends upon the characteristics of the impulsive excitation and the physical properties of the structure. During an earthquake, failure of structure starts at points of weakness. This weakness may arise due to discontinuity in mass, stiffness or geometry of structure. The structures having one of these discontinuities are termed as irregular structures. Vertical irregularities are one of the major reasons of failures of structures during earthquakes. For example, structures with vertical setback were one of the notable structures that collapsed during earthquakes. Height-wise differences in stiffness and mass render the changes in dynamic characteristics of these buildings resulting in failure during earthquakes.

The objective of this paper is to investigate the response of RC Space Frame with vertical setback to dynamic disturbances viz. earthquake and blast loading and determine the variation in response to variations in load and the characteristics of the structure. For this study an advanced method viz. Applied Element Method (AEM) has been used for the analysis. It can be observed from the results that the maximum X-displacement for Blast load of 2500kg TNT and Earthquake load were comparable at all storey levels. The percentage increase in X-displacements for blast loads of 2500kg TNT when compared with 1000kg TNT is ranging from 40% to 60% for a range of plinth level (+0m) to +18m storey level.

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A Theoretical Model for Road's Emergency Evacuation during Earthquake based on System Dynamics in Crowded Areas

Liu Xiaoran*, WangWei and Li Xiuyuan

Through the overall analysis for the influence factors of roads' emergency earthquake evacuation in crowded areas, we concluded that the dynamic feedback during earthquake evacuation involves three aspects: disaster environment, road space and personnel characteristics. Based on these aspects, the road evacuation causal model and flow model with system dynamics were established.

In reference to the standard “Urban planning on earthquake resistance and hazardous prevention” of China, parameters for emergency shelter, evacuation road and evacuation time were set and the other parameters can be set with reference to past research. Finally, the dynamic simulation on the road evacuation capabilities in a crowded area during the earthquake was conducted and related planning recommendations were given for densely populated areas from the results. The study provides a reference for the urban earthquake relief work.

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Deconstruction research to determine the jointed rock mass caving recovery roadway roof risk area

Chen Qing-fa*, Zheng Wen-shi, Niu Wen-jing, Liu Jun-guang and Zhao Fu-yu

It is obvious that engineers always depend on their experience instead of a scientific and rigorous approach to determine the dangerous area of the roadway roof during the recovery progress of jointed rock mass caving. In this paper, the block theory is used to provide an exact delineation method of caving mining process roadway roof dangerous area. The main contents of the method include the following:

(1) Preliminary deconstruction of several structural bodies of the jointed rock mass roadway roof and determination of several parameters including structure scale, occurrence location, status and minimum fixed area;
(2) Combined with caving mining technology, we used a vector method to determine that the structure exists in the roadway roof before and during the mining recovery progress to establish the potential mobile structure;
(3) Based on the analysis and results of the structure movability, we calculated from the mechanical perspective the structural stability of the roadway roof within caving exploitation and
(4) Based on the structure mobility and the analysis of stability and by coupling of the General Block software and the 3DMine software, the following are revealed:

The occurrence pattern of the dangerous structure of the roadway roof in 3D and centralized occurrences in the area of the dangerous structure are delineated roof danger zone. We selected a section of the roadway of the Guangxi Tong-keng Mine fractured ore rock as the experimental zone to undertake the study. The results show that the roof along the Y axis direction 0 m~3 m and 12 m~20 m is the danger zone during the test area roadway caving stoping process; there are 120 dangerous structures in the dangerous area; 2 structures may fall; 2 structures may have a single sliding and 116 structures may be double-sided sliding.

The results are highly consistent with the field analysis and the results of the research can provide reliable technical support for accurate delineation of the fractured rock roof of roadway hazardous area.

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Evaluation of hazardous resistant suitability for land based on variable weight set pair analysis and Vague set theory

Li Bo, Wang Wei* and Li Xiaoxing

According to the complexity, uncertainty and dynamics of evaluation of hazardous resistant suitability for land, a coupling model based on set pair analysis and Vague theory was established in this paper. Surface rupture, liquefaction of sandy soil, settlement of soft soil, collapse and landslide, engineering geology classification and site classification were taken as affected factors of suitability evaluation. In order to avoid neutralizing the negative impact caused by poor indicators, variable weight theory was incorporated into the coupling model. Ten sets of data were selected as calculating example. The performance of coupling model was compared with expert analysis method and constant weight Analytic Hierarchy Process (AHP) model. The results showed that the coupling model had good stability and discriminant results were more accurate.

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The Impact of Cyclonic Importance Factor and its effect on A type and Lean-to Roof Trusses

B. Santhosh Kumar*, Balaji K.V.G.D. and Patnaikuni Chandan Kumar

To rationalize the cyclonic wind speeds in a coastal region, IS 875 (part3):2015 introduced a cyclonic importance factor (K4 factor) for computation of design wind speeds. The proposed factor has a value of 1.15 for industrial structures and 1.30 for post- cyclonic importance of structures. This paper presents the impact of K4 factor on A type and Lean-to roof steel trusses which are widely used in industrial and other sectors. Trusses of 9m and 12m spans with roof slopes 1 in 3 and 1 in 5 for three building permeability conditions are studied.

Trusses are analyzed using STAAD Pro 8i software for the previous code of IS 875(part3):1987 and revised code of IS 875(part3)-2015 along with K4 factor for all viable combinations. The results suggest that truss forces in A-type truss varies from 8% to 9% in the industrial structures category, 39% to 44% in post cyclonic importance category for a span of 9m. The forces in Lean- to roof truss vary from 1% to 3% in the industrial structures category, 42% to 47% in post cyclonic importance category for a span of 9m. The forces are relatively less affected in 12 m span for both types of trusses.

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