Libas Textiles Ltd (9500)

Transcription

1 Revision : Issue 01 Date: Libas Textiles Ltd (9500) Nishchintopur, Mouchak, Kaliakoir, Gazipur, Bangladesh. ( N, E) 22.MARCH.2014 Client Summary Report Observations & Actions Written By Thai Tang Anh Reviewed By Anthony Liu Approved By Geoff Minto RED

2 Executive Summary On Mr Anthony Liu (lead) and Mr Thai Tang Anh carried out a visual structural survey of the Libas textiles Ltd at the address and co-ordinates given on the cover page of this report. We met with Lt Col M.A. Mannan (retd) (Executive Director ). We were provided with copies of Architectural and Engineering Design drawings and these appeared to be permit drawings. We were informed that the building dated from between 2005 and These drawings generally matched the actual site conditions, although we had reservations regarding their accuracy. The factory building is used for garment manufacturing on all floors of the building We inspected the whole building, which was made accessible to us in all parts, only to look for conditions concerning imminent danger to people, and identified potential issues which do not pose imminent danger to the stability of the building, but which should be fully checked by the building engineer and the appropriate remedial steps taken, We have major concern with the structure of one of the buildings, and we would opine that the building is unsafe for use and possesses a significant risk to human life for those working within its confines. In light of our investigation, we would consider immediate evacuation of the whole building to be expedited.

3 Executive Summary (continued) At this point we see urgent reasons to suspend operations in one of the buildings due to these concerns (and subject to the immediate responses to the required actions noted at the end of this report). Further actions with associated priorities and timeframes are given at the end of this report. Please note that these actions should be completed as soon as possible and certainly within the timeframe noted. We have reviewed the property from an outline seismic perspective and would consider that the building along with many others in the Dhaka region to have a significant risk in a major Seismic event. We have some concerns with the stability system in day to day loading conditions and require this be addressed in a Detailed Engineering Assessment. We have carried out some on-site testing and preliminary analysis to support the findings of this report. Our Limitations and Assumptions are also noted at the end of this report. This short report has 4 sections namely: 1. Executive Summary (this section) 2. Short Graphical Section showing key issues observed 3. Priority Action List 4. Limitations and Assumptions

4 Building 02 Building 01 Master plan of the site comprising the following buildings : 2 Main buildings 10 sheds The inspection was focussed on Buildings 01 and Buildings 02, but there was insufficient time to inspect the sheds. However, from visual inspection, these sheds appeared to be in satisfactory visual condition. Building Extents (Master Plan)

5 5-storey reinforced concrete building Extension area Longitudinal column grid spacing of 7.92m Transverse column grid spacing of 6.40m Building 01 Extents (Front Elevation)

6 Building 01 Extents (Left side elevation) Extension area

7 Building 01 Extents(Rear elevation ) Single-storey shed unit behind main building 01.

8 3-storey reinforced concrete building Longitudinal column grid spacing of 4.36m Transverse column grid spacing of 10.04m Building 02 Extents (Front Elevation) Structural Grid

9 Shed with steel truss roof two-storey only. Unfortunately, due to time constraints, we were unable to examine this building. Shed Extents

10 Other ancillary building on the site. Again, due to time constraints, we were unable to examine these buildings but they appeared to be structurally sound. Shed Extents

11 Original Structural Drawing of Building 01 (from 2005) Building Extents

12 Original Structural Drawing of Building 01 Extension (from 2005) Building Extents

13 Original Structural Drawing of Building 02 (from 2005) Building Extents

14 R.C Framing structural system Stability provided by movement frame action and brick in-fill walls Slab Thickness 152mm Column Size 500x625mm (typ.) Typical Floor plan of Building 01 (Excluding Extension) Grid 7.92m x 6.40m Building 01 Extents

15 Building 01 Extents (Roof ) The final floor construction is imminent.

16 R.C Framing structural system Stability provided by movement frame action and brick in-fill walls Slab Thickness 152mm Column Size 254x381mm (typ.) Grid 10.04m x 4.36m Typical Floor Framing Plan (missing cantilever section) Building 02 Extents

17 Building 02 Extents (Roof ) Roof has internal flush ceiling, but has upstand beam system outside.

18 Identified Priority 1 Concerns

19 1 st Priority 1 Concern Based on the load rundown analysis following the agreed minimum design live load assignment, the columns seem significantly insufficient in carrying the dead and live loads from the 3 storey in building 02, giving a firm RED warning. The building was constructed before 2005, with brick aggregate, with total of 3 storeys (including roof). In addition, the ferroscan indicated a steel provision which was not in accordance with the record drawings Building 2 Column rundown with scanned rebar is insufficient (RED)

20 nd Priority 1 Concern Building 02 structural layout appears to be dangerous: Beam span is excessive, and beam size is too small. Span beam is 10.04m,beam size is 381x254 mm: Span/depth ratio is 10,040/381= 26.35> 20.0 Span Cantilever is 4.00m Beam section is 381x254 mm : Span/depth ratio is 4,000/381= 10.5 > 7.0 Rebar provision also appears to be seriously underprovided. Building 02 structural layout appears to be dangerous

21 3 rd Priority 1 Concern During the inspection, we accessed the roof. Even a slight foot shuffle caused major vibration of low frequency to the structure, and deflection of the roof was physically detectable by visual as well as feel. As can be seen the upstand beam has a span of 10m, and appears to be seriously undersized. Building 2 Vibration on roof is a significant cause for concern

22 Temporary steel post 4 th Priority 1 Concern A previous inspection by a structural engineer also proved that the structural integrity of this building is of major concern. Steel props have been added to the mid-span of the beam as a temporary measure to provide stability, however their installation was not considered to be safe, as none of the surface finishes of the beam were removed, and the punching shear on the floor slab is also of major concern, as there is no foundation directly beneath these posts. Top and Bottom connection Building 2 Beam is propped at midspan by temporary steel post on ground-bearing slab

23 5 th Priority 1 Concern According to the original layout drawings, the architectural layout and structural layout are different. The architectural drawing shows the tapered edge of the building, whilst the structural plan remains rectangular. The tapered section of the building is completely cantilevered, with no columns or footings to support. Building 2 Old structural plan does not reflect structural layout, and new structural drawings are incorrect

24 Identified Priority 2 Concerns

25 1 st Priority 2 Concern The fire escape staircases were added by the factory owner after completion of the building. These staircases are deemed to be unfit for their purpose as the structural framing does not appear to be able to withstand emergency crowd loading. The balustrades are also not designed to take lateral crowd loading, and all the members have not been galvanised. Significant rusting of all the steel members was observed Fire escape staircases are not suitable for emergency use

26 2 nd Priority 2 Concern Rebar number of Column C11 is not in accordance with structural drawings. On site condition rebar number of column C11 is only, instead of as shown in the drawings Rebar of Column C11 is not in accordance with structural drawings

27 3 rd Priority 2 Concern R.C Framing structural system in Drawing Flat slab structural on site condition. Flat slab of extension of Building 1 has no detail. In the drawings, only the roof slab was detailed (comprising a beam and slab system). A full structural inspection and checking is required. It was advised that the flat slab was 229mm thick, although this could not be confirmed Flat slab of extension of Building 1 has no detail. A full structural inspection and checking is required.

28 4 th Priority 2 Concern Each water tank is estimated to have a maximum weight of approximately 2000kg. As there are 4 tanks arrangement is closed the total weight of 4 tanks is about 8000kg. (78.5kN). Based on a plan area of 3.5mx3.5m, the equivalent live load is estimated to be: 78.5kN/(3.5x3.5)m 2 = 6.4kPa. The allowable live load is believed to be max. 3.0kPa in Building 01 Water Tank are arranged close on Roof at Building 01

29 Identified Priority 3 Concerns

30 1 st Priority 3 Concern There are original drawings from 2005 and new structural drawings from The new structural drawings were allegedly created by a combination of backcalculation of the structure, as well as some kind of in-situ investigation. However, the drawings have been proven to be significantly different from the original drawings which we believe have been used to construct the buildings. We therefore believe the new structural drawings to not be satisfactory and non-representative of the site conditions. We would also advise that the structural safety certificate to be revoked as Building 02 has already been deemed to be structurally unsafe to a signficant degree. A full structural review of the as-built structure should be carried out to establish the actual site condition, and new detailed structural drawings should be developed. We would advise that the drawings must be completed prior to the construction of the final floor of the building.

31 Problems Observed Summary ITEM 1: (1 st Priority 1) Preliminary load take-down calculations suggest that structure does not comply with the BNBC regulations with regard to required design loading in Building 02. ITEM 2: (2 nd Priority 1) Building 2 structural layout appears to be dangerous ITEM 3: (3 rd Priority 1) Building 2 Vibration on roof is a significant cause for concern ITEM 4: (4 th Priority 1) Building 2 Beam is propped at midspan by temporary steel post on ground-bearing slab ITEM 5: (5 th Priority 1) Building 2 Old structural plan does not reflect structural layout, and new structural drawings are incorrect ITEM 6: (1 st Priority 2) Fire escape staircases are not suitable for emergency use

32 Problems Observed Summary (Continued) ITEM 7: (2 nd Priority 2) Rebar of Column C11 is not in accordance with structural drawings ITEM 8: (3 rd Priority 2) Flat slab of extension of Building 1 has no detail. A full structural inspection and checking is required. ITEM 9: (4 th Priority 2) Water Tank are arranged close together on Roof at Building 01 ITEM 10:(1 st Priority 3) There are original drawings and new structural drawings. The new structural drawings do not match with the original structural drawings, NOR do they reflect site as-built condition. A full structural review of the as-built structure should be carried out to establish the actual site condition. The new drawings are unreliable.

33 Item 1,2,3,4,5 and actions Building 02 is deemed unsafe for usage due to unsafe structure on all aspects. Priority 1 (Immediate Now) Priority 2 (within 6 weeks) Cease operations in Building 02 immediately It is deemed that the building is unusable based on the current structural layout None requried Priority 3 (within 6-months) None requried

34 Item 6 and actions The Steel escape staircase is deemed unfit for its purpose as an emergency structure Priority 1 (Immediate Now) None requried Priority 2 (within 6 weeks) Consider to replace the staircase and design in accordance with emergency escape regulations with regard to loading Apply galvanised coating to all steel members if a new steel structure is chosen. Priority 3 (within 6-months) None requried

35 Item 7 and actions Structural record drawings do not reflect the as-built condition Priority 1 (Immediate Now) None requried Priority 2 (within 6 weeks) Priority 3 (within 6-months) Building Engineer to fully check loading from the building from both current loading as well as future loading cases to establish whether or not the as-built column is able to sustain the loading Carry out works in accordance with the priority actions of Item 8 and Item 10

36 Item 9 and actions Water Tank are arranged close on Roof at Building 01. Priority 1 (Immediate Now) None requried Priority 2 (within 6 weeks) Re-arrange the water tanks on roof, and ensure that the live load is less than 3.0Kpa Priority 3 (within 6-months) None requried

37 Item 8, 10 and actions As-built structural detail does not match with the drawings Priority 1 (Immediate Now) None requried Priority 2 (within 6 weeks) Priority 3 (within 6-months) Carry out full building survey using both intrusive and non-intrusive techniques. Carry out concrete cores of structural elements to determine concrete strength Based on the building survey, develop full structural records, and also propose strengthening works or repair works if the asbuilt structure appears to be insufficient in any way.

38 Detail Engineering Assessment This Schedule develops a minimum level of information, Analysis and testing expected as part of a Detail Engineering Assessment. The building(s) have been visually assessed and it is deemed necessary that a detailed engineering assessment be carried out by a competent Engineering Team employed by the factory Owner. This request should be read in conjunction with the BUET developed Tripartite Guideline document for Assessment of Structural Integrity of Existing RMG Factory Buildings in Bangladesh (Tripartite Document), the latest version of this document should be referenced. This document also gives guidance on required competency of Engineering Team. We expect that the following will be carried out: 1. Development of Full Engineering As-Built Drawings showing Structure, loading, elements, dimensions, levels, foundations and framing on Plan, Section and Elevational drawings. 2. The Engineering team are to carry out supporting calculations with a model based design check to assess the safety and serviceability of the building against loading as set out in BNBC-2006, Lower rate provisions can be applied in accordance with the Tripartite Guidance following international engineering practice, justification for these lower rate provisions must be made. 3. A Geotechnical Report describing ground conditions and commenting on foundation systems used/proposed. 4. A report on Engineering tests carried out to justify materials strengths and reinforcement content in all key elements studied. 5. Detailed load plans shall be prepared for each level showing current ad potential future loading with all key equipment items shown with associated loads. 6. The Engineering team will prepare an assessment report that covers the following: As-Built drawings including Plans at each level calling up and dimensioning all structural components Cross sectional drawings showing structural beams, slabs, floor to floor heights, roof build-ups and Basic design information of the structure Highlight any variations between As-built compared to the design structure Result of testing for strength and materials Results of geotechnical assessment and testing/investigation Details of loading, inputs and results of computer modelling Commentary on adequate/inadequacy of elements of the structure Schedule of any required retrofitting required for safety or performance of Structure Any proposals for Retrofitting to follow guidance developed in the Tripartite Document

39 Survey Limitations and Assumptions This report is for the private and confidential use of Accord for whom it was prepared together with their professional advisors as appropriate. It should not be reproduced in whole or in part or relied upon by third parties for any use without the express written permission of WSP. This report can be used in discussion with the supplier or factory owner as a means to rectify or address any observations made. The report is not comprehensive and is limited to what could be observed during a visual inspection of the building. This report is not intended to be treated as a generalised inspection and does not cover the deterioration of structural members through dampness, fungal or insect attack, nor does it deal with problems and defects of non-structural nature. Other non structural aspects of the building such as fire safety have not been assessed in this survey. Except as otherwise noted, drains and other services were not viewed or tested during our inspection and are therefore similarly excluded from this report. We have not inspected any parts of the structure which are covered, unexposed or inaccessible and we are therefore unable to report that any such part of the property is free from defect. External inspection of the façade walls has generally been carried out from ground level only by visual sighting. No opening up works were carried out (except as noted) and we rely on the Architects and Engineers drawings provided to use for our views on concealed parts of the structure and in particular foundations. Strengths of materials and components are untested and we recommend that the factory owners Building Engineer carries out insitu testing over and above those suggested to satisfy themselves with the material strengths and component details. Recommendations, where given, are for the purpose of providing indicative advice only, are not exhaustive, relate solely to identifying key and obvious structural defects as identified in this presentation, and do not take the form of or constitute a specification for works. We take no responsibility for the works as constructed. This report does not interfere with the factory owners Building Engineers responsibility for the structural performance of this building. The Building Engineer remains fully responsible for the structural adequacy of the building. This report does not comment in detail on the future seismic performance of the building and only highlights the fact that the building may experience significant damage or collapse in a seismic event along with many others in the Dhaka region. The observations in this report are based on the Engineering Judgement of the lead surveyor/engineer at the time of the survey. We assume in making these observations that no covering up of faults defects, filling or plastering over cracking or significant repair work has been carried out by the building owner. Any future alterations or additional work by the building owner will void this report.