1、MIL-HDBK-26 19 9999970 0070953 4 INCH-POUND MIL-HDBK-826(SH) 11 October 1991 MILITARY HANDBOOK DRYDOCKING TIMBERS AND BLOCKS, STRENGTH PROPERTIES OF AMSC NIA FSC 1950 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Provided by IHSNot for ResaleNo reproduction or net
2、working permitted without license from IHS-,-,- MIL-HDBK-26 19 = 9999970 0070954 b MIL-HDBK-826(SH) 11 October 1991 FOREWORD 1. This military handbook is approved for use by the Naval Sea Systems Command, Department of the Navy and is available for use by all departments and agencies of the Departme
3、nt of Defense. 2. Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to: Commander, Naval Sea Systems Command, SEA 5523, Department of the Navy, Washington, DC 20362-5101 by using the self-addressed St
4、andardization Document Improvement Proposal D Form 1426) appearing at the end of this document or by letter. 3. This document supplements departmental manuals, directives, military standards, etc., and provides basic and fundamental information on drydocking timbers and built-up blocks. 3. ii Provid
5、ed by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-n -3 MIL-HDBK-826(SH) 11 October 1991 CONTENTS Paragraph Page 1 . 1.1. 1.2 SCOPEANDPURPOSE 1 Scope 1 Purpose 1 . 2 . 2.1 2.1.1 2.1.2 2.2 2.3 APPLICABLE DOCUMENTS 1 Government documents 1 Specifications 1 Othe
6、r Government publications . 1 Non-Government publication . 2 Order of precedence 2 3 . 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 DEFINITIONS 2 Build-up blocks . 2 Cribbing . 2 End matching 2 Equilibrium moisture content (EMC) 2 Fiber saturation point (FSP) . 2 Fiber stress at proportional limit (FSPL
7、) 3 High blocks . 3 3 Moisture content (MC) 3 Softcap 3 Modulus of elasticity (MOE) . 4 . 4.1 4.2 4.2.1 4.2.2 4.2.3 4.2.4 4.3 4.4 GENERAL CONSIDERATIONS FOR STRENGTH PROPERTIES OF DRYDOCKING TIMBERS . 3 Elastic strength properties . 3 4 4 Relationship between FSPL and MOE in compression perpendicula
8、r to the grain . 5 Statistical prediction of FSPL and MOE 5 Relationship of specific gravity to. strength properties 5 Effect of moisture content on strength properties 6 Strength properties . 3 Fiber stress at proportional limit (FSPL) Modulus of elasticity (MOE) . 5 . RECOMMENDED VALUES FOR TIMBER
9、 PROPERTIES IN DRYDOCK CALCULATIONS 7 5.1 General 7 5.3 Lateral friction coefficients 8 5.2 Compressive strength properties . 7 iii Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-HDBK-826(SH) 11 October 1991 CONTENTS Paragraph Page 6 . 6.1 6.2 6
10、.2.1 6.2.1.1 6.2.1.1.1 6.2.1.1.4 6.2.1.1.5 6.2.1.1.7 6.2.1.1.10 6.2.1.2 6.2.1.2.1 6.2.1.2.1.1 6.2.1.2.1.2 6.2.1.2.1.3 6.2.1.2.2 6.2.1.2.2.1 6.2.1.2.2.2 6.2.1.2.2.3 6.2.2 6.2.2.1 6.2.2.2 6.2.2.3 6.2.2.3.1 6.2.2.3.2 6.2.2.3.3 6.3 6.3.2 6.3.3 6.3.4 6.4 6.4.2 6.4.3 6.4.4 6.4.5 COMPRESSIVE TESTING . 8 Ge
11、neral . 8 Compression tests on individual timbers . 9 Tests on oak and Douglas fir 9 Initial compression tests . 9 Testresults . 9 Conclusions 10 Test procedures 11 Preliminary work . 11 Compression test . 12 Additional compression tests 12 Test on frozen and unfrozen timbers . 12 Testresults . 12 C
12、onclusions 14 Test procedures 14 Test on varying load-to-grain angle 15 Testresults . 15 Conclusions 16 Test procedures 16 Tests on laminated red oak . 16 Test results . 17 Conclusions 18 Test procedures 19 Lamination of timbers 19 Pressure treatment of laminated timbers . 19 Compressive tests . 21
13、Compressive tests on layered timbers . Conclusions 23 Testing procedures 23 Compression tests on medium height (standard U.S. Navy) composite block build-ups 24 Testresults . 24 Conclusions 26 Comparison of medium block tests with previous tests 26 Testing procedures 27 21 Testresults . 22 Provided
14、by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-HDBK-826 17 9779770 0070757 L MIL-HDBK-826(SH) 11 October 1991 CONTENTS Paragraph Page 6.5 6.5.1 6.5.2 6.5.3 6.6 6.6.2 6.6.3 6.6.4 Stability characteristics of high blocks . 27 Testresul ts 32 Conclusions .
15、33 Testing procedures . 33 Friction tests for cribbing material . 34 Testresul ts 34 Conclusions . 35 Testing procedures . 35 7 NOTES . 36 7.1 Issue of DODISS 36 7.2 Subject term (keyword) listing 37 Tables I . II . IV . III . V . VI . VI1 . VI11 . IX . X . XI * XII . XII1 . XIV . xv . XVI . XVII .
16、XVIII . Pooled test results for all new Douglas fir and oak timbers . 7 Pooled test results for previously used Douglas fir and oak timbers 7 Comparison to published values for new oak and Douglas fir 8 Summary of coefficients of friction for various interfaces (150 lb/in2 vertical load) 8 9 Summary
17、 of compressive tests on individual timbers. MOE (ksi) . 10 Summary of compressive tests on unfrozen/frozen timbers (FSPL) Summary of compressive tests on unfrozen/frozen timbers (MOE Summary of compressive tests on timbers with varying load- Summary of compressive tests on individual timbers. FSPL
18、(lb/in2) Stress at proportional limit (lb/inz) 13 Modulas of elasticity (kis) . 14 to-grain angles 16 Compressive test results for laminated timbers . 17 18 19 Comparison of strength properties of laminated and sawn timbers . Before and after treatment weights and estimated moisture contents of lami
19、nated compression tests specimens (6 x 14 x 24 inches) . Chromated copper arsenate solution absorption (solution concentration Summary of compressive tests on one and three layers of timbers . 22 Summary of compressive tests on medium block build-ups . 25 Comparison between medium height build-ups a
20、nd individual timbers 25 Tests on Norfolk composite blocks (timber and concrete) 28 Tests on composite blocks. old (timber and concrete) . 29 1.6 percent . 20 V Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,- MIL-HDBK-26 19 I 9999970 0070958 3 = MIL
21、-HDBK-826(SH) 11 October 1991 CONTENTS Tables XIX . xx . XXI . Figures 1 . 2 . 3 . 4 . 5 . 6 . 7 . 8 . 9 . 10 . 11 . 12 . 13 . 14 . 15 . 16 . 17 . 18 . 19 . 20 . 21 . 22 . 23 . 24 . 25 . 26 . 27 . Page Test on composite blocks new (timber and concrete) . 30 compression test . 31 laterally-loaded cri
22、bbing-friction tests . 35 Comparison of deflection and apparent MOEs of block Summary of coefficients of friction for four interfaces based on Sample dry dock blocks . Relationship between compression and load . Distribution of oak timbers in transverse compression 41 Test specimen identification sh
23、eet . Moisture content and specific gravity determinations . 43 38 39 40 42 Single timber test . 44 Timber photographs . 45 Compressive test results on matched timbers of frozen and unfrozen 46 Relationship of FSPL and MOE for new and used oak timbers . Douglas fir and oak (average range of values)
24、Stress-strain diagram . 47 Compressive load direction (4 x 12 inch components) 48 Stress-strain curves for laminated red oak timbers . Stress-strain curves for solid sawn oak timbers . Testing pattern for laminated timbers . Laminated timber ready for testing in 600.000-lb . Universal testing machin
25、e 52 Test specimen under a 2-kip preload . Test specimen at 0.5 in . deflection (0241b/in2) 53 Test specimen under 500 kip load (1431 lb/inz) 54 Test specimen reload to 2 kips after test . and southern pine timbers Three-layer timber identification sheet Three-layer test of old oak Medium composite
26、block build-up tests . 59 Compressive tests on medium block build-ups Comparison of old and new blocks Composite build-up after compression . 49 50 51 53 54 Timber layer tests 55 Compressive tests on one and three layers of oak. Douglas fir. 56 57 58 60 61 62 . . vi Provided by IHSNot for ResaleNo r
27、eproduction or networking permitted without license from IHS-,-,-. MIL-HDBK-26 19 9999970 0070959 5 MIL-HDBK-826(SH) 11 October 1991 CONTENTS Figures 28 . 29 . 30 . 31 . 32 . 33 . 34 . 35 . 36 . Page Reference photograph of composite build-up 63 Scale model test of 12-foot high block build-up with 3
28、0 degree High block build-up model load deflection curve . 65 Laterally-loaded friction tests on four interfaces (average7 and ranges for four tests) 67 Test identification sheet . 68 Friction test Set-up 70 Stress-strain and lateral deflection diagram . 71 contact angle loading (scale: 1 inch = 10)
29、 . 64 Cribbing friction test arrangement 66 Frictional resistance test . test machine arrangement 69 vii Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-HPBK-826 19 9997770 O070760 L MIL-HDBK-S26(SH) 11 October 1991 1. SCOPE AND PURPOSE 1.1 Scope
30、. This handbook presents compressive strength properties for drydocking timbers and built-up blocks, stability characteristics of high blocks, and friction coefficients for cribbing materials. These values are the result of a series of tests performed under the direction of the Naval Sea Systems Com
31、mand and are intended to supplement the strength properties of clear wood specimens found in wood handbooks. The timbers used in this study were full-size white and red oak and Douglas fir and consisted of both new (unused) and in-service drydock timber. Because of the variations in strength propert
32、ies of docking timbers as determined in this study, meaningful engineering calculations on hull block loading need to be conservatively based on the low end of the ranges presented for strength properties. 1.2 Purpose. The purpose of this handbook is to establish the expected degree of performance f
33、or typical drydocking timbers and built-up blocks based upon full-scale testing results of new and used docking materials. 2. APPLICABLE DOCUMENTS 2.1 Government documents. 2.1.1 Specifications. The following specification forms a part of this document to the extent specified herein. Unless otherwis
34、e specified, the issues of this document is listed in the issue of the Department of Defense Index of Specifications and Standards (DODISS) and supplement thereto, cited in the solicitation (see 7.1). SPECIFICATIONS MILITARY MIL-W- 15 154 Wood Laminates, Oak (For Ship and Boat Use) (Unless otherwise
35、 indicated, copies of federal and military specifications are available from the Standardization Documents Order Desk, Building 4D, 700 Robbins Avenue, Philadelphia, PA 1911 1- 5094.) 2.1.2 Other Government publications. The following other Government publication forms a part of this document to the
36、 extent specified herein. Unless otherwise specified, the issues are those cited in the solicitation. PUBLICATIONS NAVSEA 090 1 -LP-997-oooO Docking Instructions md Routine Work in Dry Dock, Chapter 997 1 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,
37、-,- MIL-HDBK-82b 19 9999970 0070963 3 MIL-HDBK-826(SH) 11 October 1991 2.2 Non-Government publications. The following document forms a part of this document to the extent specified herein. Unless otherwise specified, the issues of the documents which are DOD adopted are those listed in the issue of
38、the DODISS cited in the solicitation. Unless otherwise specified, the issues of documents not listed in the DODISS are the issues of the documents cited in the solicitation (see 7.1). O0 1 -0oO-04456-7 Wood Handbook U.S. Forest Service, Forest Products Laboratory, U.S Department of Agriculture, 1987
39、 (Applications for copies should be addressed to Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402) (Non-Government standards and other publications are normally available from the organizations that prepare or distribute the documents. These documents also may be av
40、ailable in or through libraries or other informational services.) 2.3 Order of precedence. In the event of a conflict between the text of this document and the references cited herein (except for related associated detail specifications, specification sheets or MS standards), the text of this docume
41、nt takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained. 3. DEFINITIONS 3.1 Built-up blocks. Built-up blocks are drydocking blocks that generally consist of a large base concrete block, upon which layers of supp
42、ort timber are stacked, followd by a “soft cap“. Figure 1 illustrates a typical built-up block. 3.2 Cribbing. Cribbing is the term used for long timbers that run between docking blocks in order to increase the lateral stability of the docking-blocks. Cribbing material is held in place by the frictio
43、n of the docking blocks under load. 3.3 End matching. End matching is the process by which a timber is sawn in half and each piece is subjected to differing test conditions. The results for each half may then be compared to each other. 3.4 Equilibrium moisture content (EMC). EMC is the moisture leve
44、l at which timbers that are in-service and protected frcm direct immersion and rainwater will reach to be in equilibrium with the temperature and humidity of the surrounding air. The equilibrium moisture content is typically 12 table VI contains values for modulus of elasticity. Within each box of t
45、he table are the number of specimens tested, the average test value, the range of test values, the standard deviation, and the coefficient of variation (standard deviation divided by the average expressed as percent, see 4.2.4). 6.2.1.1.3 The data in table V provides strength values that may be help
46、ful in calculations for timbers used in drydocking. The average values are within the normal range of expected strengths for these species. 6.2.1.1.4 Conclusions. The following several conclusions may be drawn from the data presented in the tables: a. A troubling aspect of the results is the range o
47、f strength values: FSPLs from 241 to 821 for old oak and 279 to 570 Ib/in2 for old Douglas fir. This data shows that some timbers in service are at the lower end of the expected range for FSPL. b. Although oak is generally considered stronger than Douglas fir, there is some overlap in properties bet
48、ween the species, particularly between the old oak and old Douglas fir for both FSPL and MOE, and between the new oak and new Douglas fir for MOE. There was no overlap of FSPL values for new oak and new Douglas fir. 10 Provided by IHSNot for ResaleNo reproduction or networking permitted without lice
49、nse from IHS-,-,-. MIL-HDBK-26 19 9999970 0070970 LI MTL-HDBK-826(SH) 11 October 1991 c. The 6 x 14 inch oak timbers appear to be stronger than the 12 x 14 inch oak timbers (both new and old). There could be several reasons for this: more and deeper checks in larger cross-sections; weaker wood in the area of the “boxed heart,“ which the larger timbers invariably had; or perhaps simply th
